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INTRODUCTION TO COMPUTERS
Chapter outline
1.1 Introduction.
1.2 Parts of a computer.
1.3 Classification of computers.
1.4 Development of computers.
1.5 Areas where computers are used.
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1.1
Introduction
In the past, people have used slow and unreliable methods to generate, send, receive and store information. However, today millions of people are using devices called computers to produce, share and store information. Before embarking on taking Computer Studies as a course, it will be necessary to ask the question: What is a computer?
Definition of a computer
A computer is an electronic device that accepts user input also referred to as data and transforms it under the influence of sets of special instructions called programs to produce the desired output referred to as information.
Data can be defined as raw facts that do not have much meaning to the user and may include: numbers, letters and symbols. Information is the processed data that is meaningful to the user. The computer is said to be electronic because it utilizes small electrical signals to process information.
Before 20th century, most information processing was done manually or by use of simple machines. Today, millions of people are using computers
In offices and at home to produce and store useful information about all Aspects of business, scientific research, government activities and Personal details. Together with other telecommunication facilities, computers have also become the fastest and most reliable means of communication. The integration of computers and, telecommunication facilities for the purpose of communication is what is referred to as information and communication technology (lCT).Computers come in different sizes and designs but the most common is a computer referred to as a personal computer (PC). Personal computers are mostly used in offices, schools, business premises and at home.
1.2 Parts of a computer
A computer is made up of a collection of different components that are interconnected together in order to function as a single entity. A computer is basically made up of a system unit and other devices convicted to the system unit called peripheral devices. Examples of peripheral devices include; the monitor, the keyboard and the mouse.
The system unit
This is the part that houses the brain of the computer called the central processing unit (CPU). The system unit also houses other devices called drives. Drives are used to store, record and read data.
Figure 1.2 shows a tower style system unit.
Peripheral devices
Peripheral devices are connected to the system unit using special cables called data interface cables that carry data and information to and from the devices. The cables are attached to the system unit using connectors called ports. .
Peripheral. Devices may be arranged as shown in Figure 1.1 with the monitor resting on top of the system unit. Sometimes, the system unit may be made to stand alone (tower style) as the one in Figure 1.2.
The keyboard
It is the most common device that enables the user to enter data and instructions in the computer by pressing its keys.
The mouse
It is a device that enables the user to issue instructions to the computer
By controlling a special mouse pointer displayed on the screen.
The monitor
The computer monitor or simply the screen is a television like device used for displaying output. It is called a monitor because it enables the user to monitor or see what is going on in the computer.
1.3
Classification of computers
Computers can be categorised according to:
Classification according to physical size and processing power
Computers can be classified into four main groups namely supercomputers, mainframe computers, minicomputers and microcomputers.
Supercomputers
They are the fastest, largest, most expensive and powerful computers available. They are able to perform many complex calculations in a fraction of a second. Because of their extreme weight, a supercomputer is kept in a special room. Due to their huge processing power supercomputers generate a lot of heat. Special cooling systems are therefore required. Sometimes the whole CPU is immersed in an aquarium like tank containing liquid fluorocarbon to provide cooling.
Supercomputers are mainly used for scientific research, which requires enormous calculations. Applications that justify use of supercomputers include aerodynamic design and simulation, petroleum research, defense and weapon analysis among others. Supercomputers are mainly found in developed countries such as in USA where they are used for advanced
Scientific research such as nuclear physics. Figure 1.3 shows an example of supercomputer.
Mainframe computers
They are less powerful and less expensive than the supercomputers. While supercomputers may be described as giant computers, the mainframes are said to be big in size. They are used for processing data and performing complex mathematical calculations. They have a large storage capacity and can support a variety of peripherals.
Mainframe computers handle all kinds of problems whether scientific or commercial. They are mostly found in government agencies, big organizations and companies such as banks, hospitals, airports etc. which Have large information processing needs. Figure 1.4 shows a picture of a mainframe computer.
Minicomputers
A minicomputer resembles the mainframe but is slightly smaller. Thus it is referred to as a small-scale mainframe computer. Although it supports fewer peripheral devices and is not as powerful and fast as the mainframe computer, it was developed as a cheaper alternative to the mainframes for smaller organizations. They are used mainly in scientific laboratories, research institutions, engineering plants and places where processing automation is required. They are well adapted for functions such as accounting, word processing, database management and specific industry applications. Figure 1.5 shows a picture of a minicomputer.
Microcomputer
A microcomputer is the smallest, cheapest and relatively least powerful type of computer. It is called a microcomputer because; its CPU is called a microprocessor, which is very small compared to that of a mini, mainframe or supercomputers. Microcomputers are also called personal computers (PC) because they are designed to be used by one person at a time.
Microcomputers are commonly used in training and learning institutions, small business enterprises, and communication centers among others. Today, the power of microcomputers has grown tremendously closing the gap that formerly existed and reserved for the minicomputers and the mainframes.
Technological advancement has seen the development of smaller and smaller microcomputers. The following are the various types of microcomputers in operation today arranged in descending order according to size.
-Not portable. It is designed to be placed on Top of an office desk.
-Portable like a briefcase. It is designed to be used by placing it on the lap hence its name.
– Small enough to fit in the pocket and can he held in the palm when being used.
Classification according to purpose
Computers can be classified according to the tasks they perform either as general or special purpose computers.
General-purpose computers
General-purpose computers have been designed to be able to perform a variety of tasks when loaded with appropriate programs. They are the most common types of computers in use today. Their flexibility enables them to be applied in a wide range of applications like document processing, performing calculations, accounting, data and information management among others.
Special purpose computers
Special purpose computers are designed to serve a specific purpose or to accomplish one particular task. Such computers can perform no other task except the one they were meant to do. This means that the set of instructions, which drive a special purpose computer, are limited in number at the time of manufacture. Examples of such computers include, robots used in a manufacturing industry production line, mobile phones for communication only and electronic calculators that carry out calculations only.
Since special purpose computers are dedicated to a single task, they can perform the task quickly and very efficiently.
Classification according to functionality
Computers can be classified according to the type of data they can process. Data can either be in discrete or continuous form. Discrete data which is also called digital data is one that can be represented as distinct values that do not have any transitional stages over time e.g. either 1 or O. Continuous data which is also called analog data can be represented as progressively changing values overtime. Computers can be classified as digital, analog or hybrid.
Digital computers
Digital computers process digital data only. Any data to be manipulated by a digital computer must first be converted to digital form. Most home appliances today are also digital in nature. For example to increase the volume of a digital television you simply press a button and it changes from 1 to 2, 3 If the same television is analog, it would have a knob
that you can continuously turn round or slide in a slot to increase or decrease the volume.
Analog computers
This refers to computers that process data that is analog in nature. Analog computers solve problems by measuring the amount of change that occurs in quantities like speed, temperature and pressure. An analog machine is usually a special purpose device that is dedicated to a single task. Analog computers are used in manufacturing process control like monitoring and regulating furnace, temperatures, and pressures. They are also used in other applications like in weather stations to record and process physical quantities e.g. wind, cloud speed, temperature etc.
Hybrid computers
Hybrid computers are designed to process both analog and digital data.
1.4 Development of computers
Before 1900, most data processing was done manually using simple tools like stones and sticks to count and keep records. Around 2000 years ago, Asian merchants came up with a special calculating tool called abacus that could be used to calculate large figures. Abacii, are still in use even today. An abacus is made up of a rectangular frame and a crossbar at the middle. It is fitted with wires or strings running across from the frame to the crossbar as shown in Figure 1.8.
, 1+5=6
Each bead has a value of 5
Crossbar
Each bead has a value of 1 4+5=90+0=0
3+5=8
Fig. 1.8: Representing numbers using an abacus
8How to represent a number using an abacus
Each bead in the lower row represents unitary values while the upper ones represent fives. To represent a number, the bead is moved to the crossbar. Those beads away from the crossbar represent zeros. The abacus in Figure 1.8 represents the number 6 908 (six thousand nine hundred and eight).
The first machine after the abacus that is usually regarded as the forerunner of modem computers was developed by an English mathematician called Charles Babbage and was named the analytical engine. After the death of Babbage in 1871 there was little improvement on his work until the 1930s. The first computer-like machine Mark 1 was designed by Professor Howard Aken of Horrard University in 1939. Mark 1 became operational in 1943. It weighed 5 tons and was 16 m long. Since then, rapid advancements in computing have been realized and can be categorised into five generations.
First generation computers (1940s to 1958)
These computers were very large in physical size and used thousands of
electronic gadgets called vacuum tubes or thermionic valves. These types of computers consumed a lot of power hence they constantly broke down due to the excessive heat generated. Examples of such computers are the electronic numeric integrator and calculator (ENIAC) and the electronic discrete variable automatic computer (ED VA C).
Second generation computers (1958 -1964)
Computers in this generation operated using tiny, solid-state electronic devices called transistors that were much smaller than the vacuum tubes. These computers produced less heat, were much faster, smaller in size and more reliable than those made with vacuum tubes. Examples of second-generation computers include IBM 1401 and 7070, UNIVAC 1107, ATLAS LEO Mark III and Honeywell 200.
Third generation computers (1964 -1970)
The third generation computers used electronic devices called integrated circuits (ICs) instead of transistors. An integrated circuit consists of thousands of small transistor circuits etched on a semiconductor called a silicon chip. The use of integrated circuit improved the processing speed and storage capacity of computers. Examples of third generation computers included smaller and less expensive minicomputers such as IBM 360 and ILL 19000 series.
Fourth generation computers (1970 to present)
51 From 1970, further technological improvement was done on the silicon chip design by compressing
more tiny circuits and transistors into even smaller space. This design produced what is called large scale integrated (LS1) and very large scale integrated (VLS1) circuits which were used in the innovation and technological development of the brain of the computer called the microprocessor. A microprocessor is a complete central processing unit (Processor) used in microcomputers. The result was development of very small computers with very high processing speed. The first microcomputer was called Apple 11 Other fourth generation computers included IBM 370 and 4300, Honeywell DPS-88 and Burroughs 7700.
Fifth generation computers
In this generation falls today’s computers that have very high processing power and speeds than theirpredecessors, and whose size is increasingly becoming smaller. These computers have special instruction sets that allow them to support complex programs that mimic human intelligence often referred to as artificial intelligence.
A lot of research is being done to try and come up with a machine that can work without human intervention. One of the most successful developments in this field is the advent of computers that can help managers to make decisions and those that can offer critical expert services to users instead of relying on human professionals.
Areas where computers are used
Computers have many advantages over other types of office and business equipments that are used for data processing functions. Three of the advantages are:
2.Computers are more accurate. As long as the correct instructions and data are entered, computers W produce more accurate results. They have the ability to handle numbers up to many decimal places without rounding off.
Supermarkets
Most retail stores use computers to help in the management of daily activities like stock control. The stock control system keeps account of what is in store, what is to be sold and what is out of stock. The management is automatically alerted when a particular item or items are running out of stock and need reordering.
Offices
Computers have increased efficiency in offices by reducing the time and effort needed to access and receive information. Most modern office functions have been automated for faster message distribution and document processing.
Banks
Special cash dispensing machines called automated teller machines (ATM s) have enabled automation of cash deposit and withdrawal services. Efficiency has also been increased due to better record keeping and document processing brought about by computers.
Industries
Computers are being used to monitor and control. Industrial processes. The computer age has seen the wide use of remote controlled devices called robots. A robot is machine that works like a human being but performs tasks that are too unpleasant, dangerous, or complex and tedious to assign to human beings.
Hospitals
Computers are used to keep patients records in order to provide easy access to a patient s treatment and diagnosis history. Computerized medical devices are now being used to get a cross sectional view of thePatient s body that enables physicians to get proper. Diagnosis of the affected part of the body with high levels of accuracy. Computers also control life support machines in intensive care units (lCU).
Transport
Computers are used to monitor vehicle traffic in a busy town, aircraft navigation and to make reservations.
Communication
Integration of computers and telecommunication facilities has made message transmission and reception to be very fast and efficient. Because of the speed with which information can be transmitted around in the world using computers the world is said to have become a global village.
Law enforcement agencies
Information held in computers such as fingerprints, photographs and other identification detailshelps law enforcers to carry out criminal investigations speedily.
Education
Computers are widely used in the teaching and learning process. Learning and teaching using computers is referred to as computer-aided learning (CAL) and computer aided teaching (CAT). For example experiments in subjects like Chemistry or Physics may be demonstrated using a special computer programs that can depict them on the screen through a process called simulation.
Domestic and entertainment
Computers can be used at home for recreational activities such as watching movies, playing music and computer games. They can also be used in storing personal information, calculating, keeping home budgets and for research in various fields.
Library services
In a computerized library, a computer enables library personnel to easily access and keep updated records of books and other library materials. Library users can also use computers to search for titles instead of using the manual card catalogue.
1.6 The computer laboratory
A computer laboratory is a room that has been specially prepared to facilitate installation of computers and to provide a safe conducive environment for teaching and learning of computer studies. The following factors must be considered when preparing a computer laboratory.
Safety precautions and practices in the computer
Laboratory
After the establishment of the computer laboratory, a number of safety precautions, rules and practices need to be observed in order to avoid’ accidental injury to the users, damage of computers or lack of a conducive environment for teaching and learning. The safety precautions and practices include:
Behavior in the computer laboratory
The following rules must be followed in and around a computer laboratory.
Protection against fire
A computer room should have gaseous fire extinguishers like those filled with carbon dioxide. Water based or powder extinguishers should be avoided because they can cause damage to computer components.
Cables insulation
All power cables in the computer room must be properly insulated and laid away from busy pathways in the room. Lay them preferably along the wall in trunks. This avoids the danger of exposing the user to electric shock and power interruptions caused by stumbling on cables.
Stable power supply
Computers are delicate devices that require a stable source of power. Power from mains supply is not always stable and may sometimes experience power surges or under voltage sometimes referred to as brownout. To protect the computer from being damaged due to power instabilities, avoid connecting it directly to the mains supply. Instead, connect it to a special device called un-interruptible power supply (UPS) then connect the UPS to the mains as shown below
The UPS charges when mains power is on and has power surge and. brownout protection capabilities. When the mains power goes off, it gives some sound alert (usually a beeping sound) to alert the user.
The UPS performs two main functions namely:
To enable continuity of work even in the absence of mains power, organizations that give critical services like banks, schools and hospitals usually install a standby generator that automatically comes on in case of a power failure. Power from the generator must pass through a UPS before being fed to the computer because it is also not stable.
NB: Generally speaking, devices that provide alternative source of power are usually referred to as power backups.
Burglar proofing
To deter unauthorized access to the computer room, it is important to implement the following controls.
Ventilation
There must be good air circulation in the computer room to avoid suffocation and overheating. Remember that both computers and human beings emit heat energy into the environment. Proper ventilation enables the computer to cool and hence, avoids damage to electronic parts that can be caused By overheating. Proper ventilation can be ensured by:
Dust and dump control
a computer laboratory should be located away from excessive dust. The room should also be fitted with special curtains that would reduce entry of dust particles. Computers must remain covered using dust covers when not in use.
Humidity should be at an optimum of 50%. Humidity lower than this allows static electricity to build up and causes damage to sensitive electronic components. also high humidity of over 70% cause rusting of the metallic parts of the computer system. To prevent both high and low humidity place humidifiers in the room
Lighting
a well lit computer room prevents eyestrain that eventually leads to headaches, stress and fatigue. It is important to adjust the brightness of the computer monitor until the eyes feel comfortable before using a computer to avoid damaging your eyes:
fit radiation filter screens. Which are specially tinted to reduce the light that reaches the eye. Avoid using a flickering monitor because this can cause extreme eyestrain that can damage eyesight.
Standard furniture
The table on which a computer is placed must be strong and wide enough to bear the weight and accommodate all the peripheral devices. The chair for the user must be comfortable, and have a straight backrest for one to sit upright as illustrated below to avoid muscle pains and backaches caused by poor posture. The seat must be high enough relative to the table for comfortable use of the hands on the keyboard and the eyes must be the same level as the top of the screen when the user is seated
Practical hands on skills
Starting-up (Booting) a computer
When the power is on, the computer automatically goes through a process of self-test and preparationfor use. This process is called booting. There are two types of booting namely:
Cold booting
This happens when the computer, originally off, is switched on by pressing the power button of the system unit.
The computer starts by checking all its components to determine whether they are functioning correctly and whether they are available for use. This process is called the power-on-self-test (POST). During this process, the monitor will display information showing the status of each device being tested. In case one of the devices is faulty or missing, this process will halt and a message alerting the user is displayed on the screen. The special program that directs the POST process iscalled the basic input output system (BIOS).
When the POST process is over, the computer displays a prompt message requesting one to start using it.
Some computers have programs that require a person to identify them selves by providing a user name and a password (a secret word given to the user) before it can allow one to use them. The process of providing such information is called logging on and it is a security measure meant to deter unauthorized users from using the computer.
Warm booting (restarting)
This happens when the computer, originally on, is forced to restart by pressing the restart button on the system unit or by pressing a combination of keys on the keyboard. It is also possible to warm boot a computer by using the restart command found in a special program called an operating system.
Shutting down a computer
It is important that the user follows the correct procedure of shutting down the computer at all times. If the procedure is not followed then loss of data, damage of programs and computer components may occur.
Procedure for shutting down a computer
(a) Click the start button on the screen.
(b) Select the shut down command from the menu list.
(c) In the computer prompt that appears, select shut down then press the enter key on the keyboard. (d) After a few seconds the message IT IS NOW SAVE TO TURN OFF THE COMPUTER appears on the screen. Switch of the system unit then the monitor.
NB: Some system units switch themselves off automatically when you do steps 3 (a), (b) and (c) above.
Keyboard layout
The keys on the keyboard can be categorized into five groups as shown in Figure 1.11.
Alphanumeric keys
Keys are labeled with alphabetic letters A-Z, numbers arranged in a line 1,2, ……..0 respectively and symbols like:?,], % etc. This group also includes the following keys: cap lock, enter tab. space bar and backspace.
Caps lock key: Pressing this key let’s the user type in upper case-letters,(capitals) To switch back to lower case letters simply press the same key again.
Enter key (return key): Pressing this key forces the text cursor to move to the beginning of the next line. A cursor is a blinking underscore (-) or a vertical beam (I) that showswhere, the next character to be typed will appear. The enter key is also used to instruct .the computer to execute a command that has been selected on the screen.
Tab key: This key is used to move the text cursor at set intervals on the same line e.g. 10 mm, 20 mm etc.
The space bar: This bar creates a space between words during typing.
The backspace key: This key deletes characters from right to left on the same line.
Function keys
Function keys are usually located along the top of the keyboard. They are labeled FI, F2 up to FI2. They are used for tasks that occur frequently in various programs. For example pressing FI key in J most programs starts the HELP MENU.
Cursor movement and editing keys
Cursor movement keys are used to move the cursor on the screen. These keys are:
Arrow keys: Pressing the right or left arrow key moves the cursor one character to right or left respectively. Pressing the upward or downward arrow key moves the text cursor one line up or down respectively.
Page up and page down keys: Pressing page up key moves the cursor up one page in case the document has many pages. Pressing page down key moves the cursor down one page in case the document has many pages.
Home and end keys: Pressing home key moves the cursor to the beginning of the current line. Pressing end key moves the cursor to the end of the current line.
Editing keys are used to delete or insert characters in a document. These are:
Insert key: This key helps the user to insert or replace a character at the cursor position.
Delete (Del) key: This key deletes characters at the cursor position from left to right.
Special PC operation keys
These keys are rarely used singly but in combination with other keys to give special instructions to the computer. They include SHIFT, CTRL, ALT and ESC keys.
Numeric keypad keys
The numeric keypad consists of a set of numbers 0 to 9 and the arithmetic signs like + (addition), (minus), * (multiplication) and / (division). They are located on the right hand side of the keyboard. The keypad is meant to help the user to rapidly enter numeric data. The numbers on the numeric keypad can only be used when the, situated on the numeric keypad, is turned on.
Otherwise, they can be used as cursor movement and editing keys when num lock key is turned off. It is important to note that not all keyboards have the numeric keypad. For example portablecomputers may lack a separate numeric keypad due to size limitations.
Practical keyboard skills
TYPING RULES:
Mouse skills
Mice (the plural of mouse) comes in various shapes, colors and designs. Today one can even get a mouse that uses wireless technology that is, it does not have a connection cable. Most mice have two buttons but some may have three. Figure 1.12 is an illustration of a mouse.
Using the mouse
When the mouse is made to slide on a flat surface, it controls a pointer on the screen, which is called a mouse pointer or a cursor. To make a selection, the pointer must be on the item that is to be selected. After selecting, the user can manipulate the item by pressing a mouse button
USING THE MOUSE:
NB: For left handed people, it is possible to change the mouse settings in order to comfortably hold it using the left hand.
Terminologies associated with the use of a mouse
Clicking: This means pressing and releasing the left mouse button once. A click often selects an object.
Double clicking: This means pressing the left button twice in quick succession. Double clicking usually opens a file or starts a program
Right clicking: Pressing the right hand side mouse button once displays a list of commands from which the user can make a selection. This list of commands is called a shortcut menu or context sensitive menu. It is called a context sensitive menu because the commands on it apply to the right clicked item.
Drag and drop: This is whereby the user drags an item from one location on the screen to another. The procedure to accomplish this operation is as follows:
COMPUTER SYSTEMS
Chapter outline
2.1 Introduction
2.2 Input devices
2.3 The central processing unit (CPU)
2.4 Output devices
2.5 Secondary (auxiliary) storage devices and media 2.6 Power and interface cables
2.7 Basic computer setup and cabling
2.8 Computer software
2.9 Criteria for selecting a computer system
Introduction
In the previous chapter, you were introduced to some of the parts or devices that make up a computer. However, a computer system requires more than just a collection of devices. The term system can be defined as a collection of independent entities that collectively work together to achieve a desired goal.
The systems approach to computing was borrowed from the social scientists who believe that all things can be viewed as being made up of small independent components(subsystems) that come together to form a bigger more complex system. For example, a school can be seen as a system with the students, teachers, accounts department and the administration as subsystems. The school system itself is a subsystem of the ministry of education! Therefore, the term computer system refers to a collection of entities that work together to process and manage information using computers. It is important to note that, systems exist whether computerized or manual. However, the computer is replacing many manual processes hence the need to study the idea of a computer system. For example, a document processing system in the secretary s office can be made more efficient by computerizing it.
A computer system consists of three main components namely the hardware, the software and the computer user (liveware). All the physical components both mechanical and electronic that make up a computer system such as the monitor, the system unit, keyboard and mouse etc. are called hardware. Software is a set of computer programs that guides the computer in each and every activity that happens inside the computer during data processing operations. Human beings by themselves have the ability though limited, to process data and manage information. Computers have been designed to help human beings to enhance the efficiency of processing and managing information. It is the human being who issues commands to a computer depending on his or her needs.
The hardware elements of a computer are generally grouped into four major categories namely input devices, central processing unit, output devices and storage devices.
Input devices
‘Data may be entered into a computer using keying devices such as the keyboard, or using pointing devices such the mouse, or by devices that automatically capture data from the source referred to as data capture devices e.g. scanners and digital cameras, or by voice recognition devices such as microphones. The main purpose of input devices is to convert the human readable data into electronic or machine readable form.
Input devices can be classified according to how they are used to enter data. This includes:
Keying devices
Keyboard and keypad
These are the most common input devices. These devices enter data into a computer by typing. Apart from a few differences, a computer keyboard is similar to the typewriter keyboard. A keypad is a miniature (tiny) keyboard which is mostly used on small portable computers, calculators palm notes, mobile phones etc.
Pointing devices
These are the input devices that enter data or instructions by controlling a pointer on the screen. Apart from the mouse, the other pointing devices include the trackball, joystick and light pen.
Trackball
A trackball works just like the mouse but instead of moving it on a flat surface, a ball fixed on its top is rolled using the index finger. As the ball rotates, it moves a pointer on the screen; one can then click its button to execute the selected command. Figure 2.1 shows a drawing of a trackball. The advantage of a trackball over the mouse is that it neither requires an extra space nor a flat surface for movement. Today some computers are coming with a track ball on top of a keyboard and a mouse.
Joystick
A joystick is an input device that looks like a car
gear lever which can be moved sideways, upwards or downwards to control the position of the cursor. Just like the mouse, it has a button which is used for selecting an item. It is commonly used in playing video games.
Light pen
A light pen is a hand held pen-like device that has a light sensitive point. A light pen can make selections, place images, draw and indicate dimensions by simply touching the screen. A light pen does not emit light ‘but instead, it reacts to the light emitted by the display using a photosensitive. detector at its base.
Scanning devices
These are devices that enter (capture) data into the computer directly. Scanners can be classified according to the technology they use to capture data. These are optical scanners and magnetic ink scanners.
Optical scanners
These types of scanners capture data using light. A special type of concentrated beam of light is passed over the object, image or text which needs to be entered into the computer. The scanner converts the data into digital form and then passes it to the computer for processing. There are three types of optical scanners:
Optical mark recognition (OMR)
These types of scanners detect marks made on a piece of paper using a soft pen or pencil. The reader scans the marks with a special type of light called infrared light. Where there are no marks, a strong light is reflected than where one exists. These types of scanners are used in marking multiple choice questions, questionnaires, selecting numbers in lottery tickets etc.
Optical bar recognition (OBR)
Bar codes are lines of different thickness that hold item information such as, country of manufacture, name of the manufacturer, and item code. The type of scanner used to read these bars is called a wand or a laser scanner. The interpretation is based on the width of the bars rather than their location. Figure 2.3 shows bar codes.
Optical character recognition (OCR) / image scanners
This is the most sophisticated type of scanner that operates like the human eye. It not only scans characters but also can scan real objects, pictures and drawings.
The most common type of this scanner is the flatbed scanner, Using this scanner, one can scan text, a real object or a picture by placing it on a glass plate exactly the way photocopy machine works. The text or a picture scanned is displayed on the screen or saved so that one can edit or print it.
Magnetic scanners
These types of scanners capture data by using magnetic technology. The data being read can either be in form of special magnetic characters or a continuous magnetic strip. The following are some of the common examples of magnetic scanners.
Magnetic-ink character recognition (MICR)
MICR was developed to help banks process cheques. MICR allows special devices to read magnetic characters written in a special format. An example of MICR device is a cheque reader that reads the cheque number, and sends the details to the computer to be used in updating the customer s account.
Magnetic stripe recognition
A magnetic stripe is a thin magnetic tape, often found at the back of a plastic card e.g. an automated teller machine card (ATM) and a credit card. An ATM card is used to get banking services without necessarily going to the counter, while a credit card allows the holder to get services in any centre where the card is acceptable. The amount spent is deducted from the holder’s bank account.
Speech recognition or voice input
Voice recognition is a type of input method where a microphone is used to enter data in form of spoken words into the computer. This method is mostly suitable for the handicapped especially those with impaired hands. Although this is a fast and easier method, it has some disadvantages.
It is complex to develop and it does not take care of speech related problem’such as accents, inflections and tone. This implies that the device must learn the unique speech of an individual.
Touch screen, digitizers and digital cameras
Touch Screen
Touch screen input method utilises the technology of a touch sensitive screen. When the user touches the screen, the computer detects the position of the finger and responds accordingly. Touch screens are mostly used in public places like in banking halls, hotels, in airports (to provide guidance information) etc.
Digitisers
A digitiser or a graphic tablet is almost similar to a light pen but instead it has a graphic tablet on which the user writes on using a device similar to a pen, called a stylus. (Figure 2.6). As the stylus moves on the tablet, it s drawing is directly reflected on the screen. Digitisers are mostly used for architectural and engineering designs.
Digital cameras
A digital camera stores its images in digital form. These images can then be streamed (entered) directly into a computer for editing or printing by connecting the camera to a computer using a special cable. As with the ordinary camera, there are two types of digitals cameras: One that can takes still images i.e. photographs and another that takes motion pictures (video).
The central processing unit (CPU)
The central processing unit (CPU) also known as the Processor is the most important component of the computer. It is actually regarded as the brain of the computer. This is so because all data processing and control operations are coordinated here. In microcomputers, the CPU is housed inside the system unit. It is mounted on a circuit board known as, the motherboard or the system board. The figure below shows the location where a processor called Cyrix is mounted on the motherboard.
The CPU has three different functional units called arithmetic and logic unit, control unit and the main memory.
Arithmetic and logic unit (ALU)
The arithmetic and logic unit is a unit of central processing unit where all arithmetic and logical operations are carried out. The basic arithmetic operations includes; addition, subtraction, multiplication and division. Logic operations are based on the computer s capacity to compare two or more values. For example, it may compare whether a piece of data is greater than or less than, equal to or not equal to etc.
In order for the ALU to be able to process data, it has special temporary storage locations called registers, which holds the data just before processing. It also holds the results after processing.
Control unit
Control unit coordinates all processing activities in the CPU as well as input, storage and output operations. It determines which operation or instruction is to be executed next. To coordinate these activities, the control unit uses a system clock. The system clock sends electric signals as its means of communication, just like the way the traffic signals or a traffic officer does in a round about or junction to direct motorists and other road users. The number of pulses per second determines the speed of a microprocessor. The faster the clock pulses, the faster the CPU hence the faster the computer can process data.
Main memory (primary storage or working storage)
Main memory also known as primary storage provides storage location for data and instructions accessed by the control unit. Computer memory can be classified into read only memory (ROM) and random access memory (RAM).
Read only memory (ROM)
Read only memory is used to store programmed instructions and data permanently or semi permanently. Data and instructions stored in ROM are those required to remain unchanged for long periods of time e.g. booting instructions, special purpose computers and computerized fuel pumps instructions etc.
Depending on permanence of the instructions or data written on it, there are four types of read only memory namely;
Mask read only memory: Once the content is written on it by the manufacturer, it cannot be changed.
Programmable read only memory (PROM): This allows the user to alter it only once after the content is written on it.
Erasable programmable read only memory (EPROM): This has a transparent quartz window through which its contents, can be erased by exposing it to ultra violet (UV) light, and then reprogrammed for another use.
Electrically erasable programmable read only memory (EEPROM): This type of ROM can be erased and reprogrammed using electricity. An example of EEPROM is the memory that stores the basic input/output system (BIOS).
Characteristics of read only memory (ROM) are;
a special type of ROM.
Random access memory (RAM)
This is the most common type of main memory. It is called random access memory (RAM) because; its content can be read directly regardless of the sequence in which it was stored. As opposed to ROM, the content in RAM is held temporarily and its content is lost once the computer is turned off Therefore, before switching off the computer, it is important that one stores (saves) his/her work in a device that offers relatively permanent storage facility.
Characteristics of random access memory (RAM) are:
Types of RAM
There are two types of-RAM namely, static RAM (SRAM) and dynamic RAM (DRAM). Static RAM is very fast compared to dynamic RAM and holds its content as long as there is power. Dynamic RAM on the other hand can only hold its content for a short while even when power is all. To maintain the content of dynamic RAM, the memory chip is designed in a way that its content is refreshed (automatically rewritten) severally per second. Static RAM is more expensive. It is mostly used to make special types of memories.
Special purpose memories
Apart from ROM and RAM there are several types of special purpose memories found insijkde the CPU or in the input and output devices. These memories are vital because they increase the overall performance of data and instructions moving in and out of the CPU. These memories include buffers, registers and cache memory.
Buffers
This is a temporary holding place that may be part of the CPU or built in an input or output device. Because the CPU is very fast compared to the input or output devices, buffers provide temporary storage so that the CPU is set free to carry out other activities instead of waiting for all data to be entered or information to be output. For example since a printer cannot work at the speed of a CPU, the printer buffers temporarily holds the output to be printed hence freeing the CPU to perform other functions. Buffers can hold more than one piece of data at a time.
Registers
As opposed to buffers, registers hold one piece of data at a time and are inside the CPU. Examples of registers are:
An accumulator: This temporarily holds the results of the last processing step of the ALU.
Instruction register: This temporarily holds an instruction just before it is interpreted into a form that CPU can understand it.
An address register: This temporarily holds next piece of data waiting to be processed.
Storage register: This temporarily holds a piece of data that is on its way to and from the CPU and the main memory.
Cache Memory
Most modem processors incorporate small high-speed type of SRAM called cache memory. The purpose of cache memory is to allow the processor to access data and instructions even faster than it would have taken to fetch it from the relatively slow DRAM.
Memory capacities
Memory and storage capacity is measured in special units called bytes. A byte is equivalent to a single character. Characters can be a number from 0 to 9, letters A to Z or a special symbo1. For example, a number like 2545 has four bytes while the words, My Home has seven bytes since, and the space between them has 1 byte.
Memory quantities can be expressed in;
Overall functional organization of the CPU
The arithmetic and logic unit, the control unit and the main memory use electrical pathways or links referred to as buses. There are three types of buses namely;
Control bus: This is the pathway for all timing and controlling functions sent by the control unit to other parts of the system.
Address bus: This is the pathway used to locate the storage position in memory where the next instruction data to be processed is to be found.
Data bus: This is the pathway where the actual data transfer takes place.
Figure 2.8 is a summary of the overall organisation of the CPU and how it controls other computer components.
| Control unit | ||||||||||||
| Instructions | Gives instructions to each | Instructions | ||||||||||
| device after interpreting | ||||||||||||
| program instructions | ||||||||||||
| Arithmetic and logic unit | ||||||||||||
| Calculates and compares | ||||||||||||
| data | ||||||||||||
| Results of | Data to be | |||||||||||
| processing | processed | |||||||||||
| Input data | Main memory | Output data | ||||||||||
| I Input unit | Stores data and instructions to | Output unit I | ||||||||||
| be processed temporally. | ||||||||||||
| Output to be | Data to be | |||||||||||
| stored | processed | |||||||||||
| Secondary storage devices | ||||||||||||
| Stores data and instructions to | ||||||||||||
| be processed permanently. | ||||||||||||
Fig. 2.8 Functional organisation of the CPU
Types of processors and their clock speeds
Processors
In 1971, a company called Intel that specialises in manufacturing central processing units managed to combine the arithmetic-logic unit and the control unit on a single tiny processor called microprocessor and called it Intel 4004. This microprocessor was used in electronic calculators. The first microprocessor to be used on microcomputers was called Intel 8086 developed in 1974. Since then, there has been a tremendous growth in microprocessor technology marked by great increase in processing capability and speed.
Until 1989, Intel corporation enjoyed monopoly in the field of microprocessor technology with her famous Intel processors. Since then other players joined in and started manufacturing cheaper alternatives. These include: Advanced Micro Devices (AMD), Cyrix and Motorola companies
Processor clock speed
The speed at which a processor executes instructions is determined by its clock speed. System clock speed is measured in hertz’s. A hertz is a unit of frequency which measures the number of cycles per second in a signal. Quantities of the clock speed can be expressed in;
There has been a tremendous growth in the processing capability and clock speed of microprocessors. From a speed lower than 4MHz, modem microcomputers can run at speeds higher 2GHz. Table 2.1 shows a summary of how microprocessors have evolved.
| Processor | Description | Clock speed |
| Intel 8086 | The two are almost identical and were used | 4.7 MHz-I0 |
| and 8088 | with the first IBMPCs 8086 was an | MHz |
| improvement of 8088. | ||
| Intel 80286 | Provided increased performance over 8086. | 6 MHz-20 |
| This was the processor that opened up the PCs | MHz | |
| to many users. | ||
| 80386SX | Apart from Intel s 80286, AMD produced | 33 MHz-40 |
| and | their versions with copied greatly the Intel s. | MHz |
| 80368DX | These were the first entry in the processor market. | |
| 80486SX | Provided over 100% better performance than | 25 MHz-50 |
| and | 80386 and were the first upgradeable | MHz |
| 80486DX | processors. AMD and Cyrix produced their version too. | |
| Pentiums | Since 1992, Intel decided to coin their fifth | 60 MHz- |
| (586) and | generation with the name Pentium instead of | presently |
| above | 80586. Pent is a Latin word that means five. | Pentium IV |
| Intel chose the word in order to distinguish its | with over 2.8 | |
| 80586 and above processors from AMD and | GHz | |
| Cyrix versions i.e. 5×86 and AMDK5 | ||
| respectively. Examples of Intel Pentium | ||
| processor are Pentium Pro, Pentium MMX, | ||
| Pentium II and currently Pentium IV at the | ||
| time of writing this book. |
Output devices
Output devices are peripheral devices that a computer uses to give out information produced after the processing operations. There are two types of output devices namely the softcopy and the hardcopy output devices. Softcopy refers to the intangible output mainly displayed on the screen or through other output devices such as speakers. A hardcopy is a tangible output produced mostly on papers by devices such as printers.
Softcopy output devices.
Some of the softcopy output devices are;
Monitors
A monitor or a video display unit (VDU) is the most common output device. It displays information on its screen thus helping the user to monitor operations carried out by the computer.
For a long time, monitors have been designed using a long tube called the cathode ray tube (CRT at emits light. The screen of a cathode ray tube is curved slightly outward forming a convex shape. However, new flat displays have come which do not use CRT technology. Flat display are more comfortable to use, portable and do not consume a lot of power compared to CRT. Figure 2.9 shows a CRT monitor and flat panel display monitor.
The sharpness or clarity of an image on the screen depends on the type of monitor being used. Monitors that display sharp clear images are said to have high resolution. The images on the screen are formed by small dots called picture elements (pixels). The higher the number of pixels per square centimeter the higher the resolution hence the clarity.
There are two types of monitors namely monochrome and colour monitors Monochrome monitors display images and text in only one colour mostly black and white. Colour monitors can display images and text in multiple colours. For a monitor to display information it must be connected to a separate piece of circuit board, plugged into the motherboard called the video card or graphics adapter. However, some motherboards have onboard video capability therefore there is no need for a video card.
Examples of graphic adapters are:
Monochrome display adapter (MDA): This was the first video card that was used in early computers. MDA displayed text only in one colour.
Hercules graphics card (HGC): One weakness of the original MDA display was that, it could not support images of any kind. Hercule graphic card supports monochrome images in addition to text.
Color graphics adapter (CGA): This can display text and images using up to 16 colours.
Enhanced graphics adapter (EGA): This is an improvement over colour graphic adapter but also displayed text and images using 16 colours.
Video graphics array (VGA): This offers at most 256 colours.
Super video graphics array (SVGA): This is an enhancement of video graphic array capabilities offering over 256 colours.
Small portable laptops, notebooks and even desktop PCs use flat-panel display. Common types of this display are:
Liquid crystal display (LCD): Liquid crystal displays do not display by emitting light of their own. Instead they have tiny liquid crystals that reflect light falling on them from the environment. Liquid crystal displays are widely used in watches, calculators, cell phones and digital cameras.
Electro luminescent (EL): These displays are an improvement on LCDs. Electro luminescent emits light when electrically charged. This makes them clear, sharper and easier to read.
Gas-plasma: These use a gas that emits light in the presence of electric current.
Thin film transistor (TFT): This is the latest technological advancement in displays. It provides high quality output than all the others.
Sound output
Speakers are used to output sound from a computer. Sound may be in form of music, warning, video, interactive communication with a computer etc.
Light-emitting diodes (LED)
These are light emitting components that display light when an electric current is passed through them. A good example is the red or green light displayed by the system unit to help the user know whether it is on or off. Mostly LEDs are used to give warnings the same way a motorist would use signals to indicate when he/she is overtaking or taking a turn.
LCD projectors project the output from the computer to a white board or wall.
Hardcopy output devices
The most common hard copy output devices are printers and plotters.
Printers
Printers produce a hard copy of information on papers. The quality of the hardcopy depends the printer s printing mechanism. There are two types of printers namely impact and non-impact printers.
Impact printers
The mechanism of impact printers is almost similar to that of an ordinary typewriter i.e. they produce characters by using special light hammers with characters or pins held on the printing head. To print, a paper is placed behind an ink ribbon. When the hammer strikes on the head, character mark is stamped. These printers are noisy and are mostly used to produce rough copies. The two widely used impact printers are dot matrix and daisy-wheel printers.
Dot matrix printers produce a hardcopy by arranging patterns of dots on the paper using pins held in the printing head. Figure 2.10 (a) shows an example of an impact printer. Figure 2.10 (b) shows print characters formed by a dot matrix printer.
a daisy-wheel printer has a wheel with petals on which characters are mounted. It is so called because it resembles a daisy flower. When printing, the wheel rotates allowing the petals to hit a ribbon with differentcharacters as they are received from the computer.
Non-impact printers
These printers do not use the striking mechanism to produce characters on a piece of paper. They do not hammer the ribbon hence they are much quieter. The major non-impact printers are inkjet, thermal transfer and laser printers.
Inkjet printers
Inkjet printers form characters by spraying ink from tiny nozzles through an electrical field that arranges the charged ink particles into characters. Inkjets are cheap to buy but expensive to run because of the high cost of ink cartridges. Figure 2.12 shows an inkjet printer.
Thermal printers
Thermal printers use heat to transfer characters onto a piece of paper i.e. they bond characters onto a piece of paper by using hot pins which pressesagainst a special ribbon. They are inexpensive alternative to inkjets.
Laser printers
Laser printers prints by passing a laser beam back and forth over a rotating drum. The laser beam draws the image on the drum by static electricity. An example of a laser printer is shown in Figure 2.13. The charged areas pick up the ink toner from a cartridge, and press it onto the paper. Although these printers are more expensive to buy, they are faster, and cheaper to run than the inkjets.
Plotters
A as shown in Figure 2.14, a plotter resembles a printer but specialises in producing big charts such as maps, pictures and drawings. They are mostly used for printing geographical, architectural and engineering drawings e.g. maps, advertisement posters to be placed on billboards, machine parts etc.
2.5. Secondary (auxiliary) storage devices and media
There is need to have an alternative long-term storage location for data and information other than the main memory. These alternative storage devices that are not part of the main memory are called secondary or auxiliary storage devices. These devices are not directly accessible by the cpu. Secondary storage devices that are not housed inside the system unit and hence can be carried around to be used with another computer are called removable storage devices and media. In order to read or store data from a storage media, a device called a drive is required.
Secondary storage devices can be classified according to the technology used to record data. The technology could be magnetic or optical. The data and instructions held in these devices must first be moved into RAM before processing.
Removable storage devices
Magnetic tapes
A magnetic tape is a ribbon of Mylar (plastic-like) material coated with a thin layer of iron oxide. The tape resembles the music cassette used in home tape recorders.
In order to read/write data records on the tape, the tape must be inserted in a tape drive that rotates the tape allowing a read/write head to perform
5.1. the operation. Most computers today don t has tape drives because of the advent of better storage devices. Examples of magnetic tapes include: reel to reel tapes, cassette tapes and cartridge tapes.
Disadvantages of using magnetic tapes
Magnetic disks
They have a magnetic disk platter that stores data. Examples of magnetic disks are floppy disks (diskettes), zip disks and jaz disk.
Floppy disks “
A floppy disk or simply a diskette is made up of a small flexible round disk coated with iron oxide. This disk is covered with a plastic protective case. Floppy disks are portable thus making them the most widely used type of secondary storage device.
Floppy disks are inserted in a floppy drive, which has a read-write head that runs over the magnetised spots that contain data. Floppy disks come in different sizes with different storage capacities. Initial floppy disks were large in size but with smaller storage capacities than the presently available 3t-inch which has a maximum storage capacity of about 1.44MB. Figures. 2.15 (a) shows a typical 3t-floppy diskette while Figure 2.15 (b) shows parts of floppy disk.
The structure of a floppy disk platter
If the protective plastic casing of a floppy disk is removed, a circular flexible disk, coated with magnetic material will be revealed. The surface of the disk is divided into tiny invisible concentric circles called tracks that store data. The tracks are further divided into units called sectors as shown in Figure 2.16.
Zip disks
These are high capacity disks that resemble the floppy disks. They are, however, slightly larger and thicker in size. A zip disk can hold as much as 250 MB. Zip disks mostly come with separate-portable external zip drive.
Jaz disks
These are small portable disks with high storage capacity of about 1 GB to 2GB. They are used for storing data that require large storage. Like jaz disk comes with a portable jaz drive. Figure 2.17 below shows jaz and zip disks and their drives.
Care of magnetic storage media
To care for magnetic media the following rules are to be observed.
weakens magnetic media s ability to store data.
Optical (laser) disks
These are disks on which data is recorded using a laser beam. A laser beam is a very strong concentrated light. The beam bums very tiny holes (pits) into a thin shiny surface to record data. Likewise a laser beam in the optical drive is also used to read, record data on the disk. The advantages of optical storage media are:
magnetic media.
Examples of optical storage disks include: LS-120 super disks (SD), compact disks (CDs), digital versatile disks (DVD), optical card and optical tape.
LS-120 super disk
This is a diskette that resembles the 3 ½-inch floppy disk but uses optical technology instead of magnetic technology to record data. It has greater capacity of storage and greater speed of data retrieval. The LS-120 drive can read and write both the 3 ½-inch, 1.44 MB floppy disk and the 120MB super disk. (Figure 2.18).
Fig. 2.18 Super disk and drive
Compact disks (CD)
Compact disks hold large quantities of data and information. One disk can hold as much as 700MB. They are mostly used to store data and information that requires a lot of space such as video clips, software, sounds etc. Figure 2.19 shows a compact disk.
Currently compact disks are available in three forms namely:
Compact disk-read only memory (CD-ROM): These are the type of compact disks which, when data is recorded on Them, one can neither change them, nor add anything on them. They are mostly used to store music recordings.
Compact disk-recordable (CD-R): These compact disks are initially blank but with a drive called CD- Writer, the user can record data, programs or information on it. However, once data has been written on it, one can only read but not change it.
Compact disk-rewritable (CD-RW): Unlike the CD-Rs, these types of compact disks allows the user to record, erase and rewrite new information just as one would with floppy disks.
NB: Both CD-ROMs and CD-Rs are referred to as WORM (Write Once Read Many) because they allow the user to record data on them once but read the data as often as necessary.
Digital versatile disks (DVD’s)
Digital versatile disks also known as digital video disks resemble compact disks in every aspect but the only difference is that they have higher storage capacity of up to 17GB which is equivalent to approximately twenty six 640MB CDs. They are suitable for recording motion pictures such as video because they offer better sound and picture quality than the CDs.
Optical card
An optical card resembles the magnetic-ink character recognition card but instead of having a magnetic stripe, it has an optically recordable stripe that stores information. These types of cards are mostly used in banking and other business organisations to record customer details.
Optical tape
This is similar to a magnetic tape only that data is stored on it by using optical technology.
Current and emerging trends in laser technology
The advances in optical storage, digital video clips, voice and sound synthesis have formed the basis for modem multimedia technology exploited to develop multimedia computers. A multimedia computer does not only display text but can also allow the user to have sound playback and watch videos and pictures. A typical multimedia computer must have the following minimum requirements:
graphics card and monitor.
Today computers can be used to tune to any of the favorite FM or TV channels as long as an FM/TV card is installed in the computer.
Fixed storage media
These are the storage devices that are housed inside the personal computer s system unit. An example is the hard disk. However it is important to note that some hard disks especially those used in small computers such as laptops are removable.
The hard disk
The hard disk, also known as the Winchester disk is a sealed unit in which is shiny, rigid magnetic disks or platters that are arranged vertically on a common axis as shown in Figure 2.20.
How the hard disk stores data
Each disk has two read/write heads that read/record data on both sides. The surfaces of each disk are divided into tracks and sectors like those of a floppy disk. Tracks along the common axis forms an imaginary cylinder. Therefore the term cylinder is sometimes used to indicate the number of tracks on one surface of a platter. For example if you say that a hard disk has ten cylinders then each disk has ten tracks on one surface. If the disk has ten platters then one cylinder will have twenty tracks:
As the disk rotates, the read/write head moves in and out over the surface to record or read data.
Hard disks have gained widespread popularity because:
Care of the hard disk
Because of the high rotational speed of the disks, it is important to observe the following precautions to avoid permanent destruction to the hard disk also called disk crash.
Emerging trends in storage devices
Because of need for vast storage prompted by today s massive data processing applications and need to carry a lot of information in easily portable storage devices, more advanced and reliable storage media are emerging. One good example is a storage device called the flash disk that is small in size (about 5 x 2 cm) but has capacity to store over 600MB ( equivalent to approximately 400 floppy disks! !). Figure 2.22 shows a diagram of a flash disk.
2.6
Power and interface cables
Power cables
Inside the system unit is a special power supply unit that supplies power to the motherboard and other internal devices. In order to connect the computer to the mains power outlet, you need power cables that link the power supply unit to the outlet.
Interface cables
All peripheral devices are connected to the motherboard hence to the CPU by special cables called interface cables. An interface cable is connected to the device on one end, and to the motherboard via ports on the other end.
The difference between the power cables and the interface cables is that the power cable supplies power to a component while interface cables transmit data signals.
There are different types of cables and parts namely;
Parallel cables and ports
Parallel cables transmit information simultaneously using a set of many conductors (wires). For example if a cable uses 8 conductors to transmit data at the same time, it is said to be an 8-bit parallel cable. The advantage of using such cables is that they transmit data faster over a short distance. These cables are mostly used to connect printers and removable storage drives like the zip drive. Figure 2.23 shows an illustration of a parallel port and cable.
Serial cables and ports
Unlike the parallel cables, serial cables transmit one bit at a time. Although they are slow, they are much more reliable than the parallel ports and therefore, their connector cables can be as long as 15 m. Serial cables are generally used to connect devices such as the mouse and some serial printers. Figure 2.24 shows a 9 and a 25 pin serial ports.
Universal serial bus (USS) cable and port
Universal serial bus is a new standard serial interface that is set to replace the conventional parallel and serial cables and ports. Currently most peripheral devices are coming with universal serial bus ports and interface cable. Although it transmits only I-bit at a time, it provides very high-speed and quality data transmission over distances of approximately 5 metres. USB supports a wide range of peripheral devices ranging from external storage drives to digital cameras. Figure 2.25 shows a USB port and its interface cable.
If a computer does not have a universal serial bus port, it can be bought and fitted on the motherboard.
Small computer systems interface (SCSI) cables and port
This port and interface cables transmit data in parallel but are faster than the parallel cables. Another advantage of the SCSI port is that one SCSI port allows us to connect up to eight peripheral devices.
Other ports and connectors. Other ports and connectors include;
5-pin DIN and 6-pin (PS/2) ports
Originally, most computers used the 5-pin DIN to connect a keyboard to the system unit but the smaller 6-pin mini-DIN also known as PS/2 interface port has almost replaced this technology. Currently most computers come with the PS/2 connector as the new standard to connect PS/2 mouse and keyboard. Figure 2.26 shows a 5-pin and PS/2 connectors
showing physical difference in size. I
Monitor ports
The two most common connectors used for monitors are the 9- Pin D and the I5-pin Hi-D connector as shown in Figure 2.27. They are called D-ports because they resemble letter D.
(Audio connectors
These are jack plugs found on a sound interface adapter used to connect speakers, microphone and other portable audio equipment.
2.7`
Basic computer setup and cabling
Having learnt about various devices and how they function, it is important to familiarise ourselves on how to setup a computer.
Before attempting to carry out any setup activity, observe the following precautions should be observed.
Tools and other requirements
The tools and requirements include;
Connecting devices to the motherboard
The following are steps for connecting devices to the motherboard.
Step 1: Identifying motherboard slots and components. Before you connect any device to the motherboard, carefully study the manufacturer s manual in order to identify the components labeled in
Step 2: Connecting the hard disk, floppy drive and optical drive. These devices are connected to the motherboard using special ribbon cables like the one shown in Figure 2.30.
The following instructions should be observed while connecting the devices:
Step 3: Connecting other peripheral devices
To connect a device to the system unit, you need to identify its port and interface cable.
NB: If the computer is completely new, programs have to be copied (installed) on the hard disk.
2.8 Computer software
As mentioned earlier, the term software refers to a set of computer programs. Its function is to guide the computer in its operations. Software can be classified according to purpose or acquisition.
Classification according to purpose:
Computer software may primarily be designed to manage the hardware resources or to help the user accomplish specific tasks. Therefore software may be classified as either system or application software.
System software
System software performs a variety of fundamental operations that avails computer resources to the user. These functions include:
System software is further divided into:
The operating system
This is a set of complex programs that work together to control execution of user programs called applications and acts as a go between (interfaces) between the applications of the computer hardware. It manages input/output and storage operations in a computer. Examples of common operating systems are Microsoft Windows 95/98/2000/XP, UNIX, Linux, Macintosh (Mac OS) and OS/2. What type of operating system software do you use in the computer laboratory?
Therefore the operating system is the main program on the computer system.
Firmware
Firmware, also referred to as stored logic is a combination of both the software and hardware recorded permanently on electronic chips. Usually, a firmware is a read-only memory chip that is mounted or plugged into the motherboard. Firmware may hold an operating system, utility programs, language processors etc.
Utility software
Utility software is a special program that performs commonly used services that make certain aspects of computing to go on more smoothly. Such services include sorting, copying, file handling, disk management etc. The two basic types of utility software are:
Networking software
This type of software is mostly used to establish communication between two or more computers by linking them using a communication channel like cables to create a computer network. Networking software enables the exchange of data in a network as well as providing data security. Network software may come as independent software or integrated in an operating system. An example of networking software is novel Netware.
Application software
Application software, also called application packages are programs that are designed to help the user accomplish specific tasks.
.Table 2.2 gives examples and uses of common application packages
| Software | Uses | Examples |
| Word processor | Typing documents like | Ms Word, Lotus |
| letters. | WordPro, WordStar. | |
| Spreadsheets | Manipulation of numeric data e.g. calculating budgets. | Ms Excel, Lotus 1 2 3 |
| Desktop | Designing publications | Adobe PageMaker, |
| Publisher | like newspapers, books. | Ms publisher. |
| Computer aided | Technical drawing. | AutoCAD. |
| Design | ||
| Databases | Keeping records and | Ms Access, Dbase. |
| files. | ||
| Graphics software | Creating and | Corel Draw,’ Adobe |
| manipulating pictures. | Photoshop. |
Table 2.2: Application packages
Classification according to acquisition
Generally computer programs can be classified according to how they are obtained as in-house developed software and standard software (Vendor off-the-shelf software).
In-house developed programs
These are programs that are uniquely designed and tailored to meet a particular user s needs. For example, a bank may decide to manage its banking operations using a unique program developed by hired programmers. These programs are not available in the shops and once developed for one company or user may not address the needs of other users.
Standard software (Vendor off-the-shelf software)
These programs are developed by software engineers, packaged and then made available for purchase through a vendor, a distributor or directly from the developer. A developer may bundle more than one but closely related software into one package to form a suite or integrated software as opposed to single-purpose software. Examples of suites are Lotus
Suite, Microsoft-Office and Corel WordPerfect while those of single purpose are QuickBooks and Sage Line 50.
The word package is sometimes used to refer to these types of software that are packaged and sold by vendors.
Advantages of standard software over the in-house developed programs are:
Criteria for selecting a computer system
The task of determining a suitable computer system for an individual or organisation is not easy. A good computer system must meet all the requirements of the user. Therefore, before selecting the computer system to implement, it is advisable to do an analysis of all the requirements necessary in order to avoid acquiring a system that may disappoint the users.
Requirements analysis for selecting a computer system should cover the following:
Hardware considerations
Some factors considered when selecting computer hardware are;
Processor speed
The processing power and speed of a computer mainly depends on the processor speed. A good computer must have high processor speed. For example a few years ago, processors used to have speeds of less than 100 MHz. However, today s Pentium processors are operating at very high clock speeds of over 4 GHz.
Scientists and engineers are aiming at producing a processor that operates at terahertz (trillion hertz). However, it is important to buy a processor that suits ones need not necessarily the fastest.
Memory capacity
As earlier mentioned, primary memory, mainly random access memory (RAM) is measured in megabytes (MB). For example, a computer may have 32MB of RAM. Although, a computer may have a very fast processor, it may not perform as expected if it has low memory capacity. Because of the current multimedia driven applications, a good computer should have sufficient memory to handle the heavy applications that require a lot of memory space in order to run. A computer with at least 128 MB of RAM is recommended for most contemporary applications.
RAM is packaged as either dual in-line memory Module. (DIMM) or single in-line memory module (SIMM).
Therefore, before one buys a memory module for the computer the following factors have to be considered:
Warranty
A warranty is an agreement between the buyer and the seller that spells out terms and conditions of, after selling a product in case of failure or malfunction.
The most important consideration to make is whether the seller is ready to actually provide after sales services. On top of the actual cost of the item, most manufacturers and suppliers include a certain percentage charge to cover the warranty.
A good warranty should cover the following points:
Cost
The cost of a computer system depends on:
It is important to do a market survey from magazines, newspapers, and electronic media or visit a number of vendors to compare prices before purchasing a computer. Computer information and technology exhibitions also enlighten a buyer on current trends and costs.
Upgradeability and compatibility
When buying a computer, the best option would be to get one that can easily be upgraded to accommodate emergent technologies. For example some older computers cannot support large hard disks available in the market today hence, difficulty in upgrading them because smaller hard disks are no longer in circulation.
Portability
The size of electronic devices including computers has become a major consideration because smaller devices enhance mobility.
User needs
When selecting computer hardware, consider the unique needs of the user. For example if the users have special disability like inability to use their hands, consider buying input devices that capture data through voice input.
The user needs also determine the type of data that will be processed hence, the choice of the type of hardware most appropriate to satisfy the needs. For example in a supermarket a special computerized devise called a point of sale (POS) terminal is most suitable to record transactions.
Other considerations
Other considerations for selecting computer hardware are;
Monitor
Depending on preference, your choice for a monitor may depend on size, resolution and the technology used to make it. Currently flat panel displays have become a new market standard quickly replacing the cathode ray tube (CRT).
Multimedia capability
This is the combination of video, audio, text and images to provide an interactive, creative and effective way of producing and communicating information. A multimedia system should have speakers, CD/DVD drive, sounds card and a SVGA monitor. It should also have software that supports multimedia capability.
Software considerations
Although one may have a good computer with the best hardware, the actual real determinant of a computer s value to the user is the software in it that can run to solve the day to day data and information processing needs.
The following factors should be considered when selecting software:
Authenticity
The term authenticity refers to genuineness, validity and or legitimacy of an item. When you acquire software from the vendor, make sure it is an original copy that is accompanied by the developer s license and certificate of authenticity. This is because some people illegally produce pirated copies which is an offence.
Documentation
It refers to the manuals prepared by the developer having details on how to install, use and maintain the software. These include installation guide, maintenance guide and a user guide. This documentation enables the user to work with the software with minimum guidance.
User needs
The needs of the user determines the type of operating system and application programs that should be considered for acquisition. For example, if the user needs to type documents most often he/she would go for a word-processor.
People with special disability will require software that recognizes other forms of input like voice and natural sound. A good example is software used in mobile phones to store voice and allow the user to make a call by just calling a name instead of keying in the number.
Reliability and security
People are more comfortable with software that offers good security to confidential and private information.
User friendliness
One of the most important features normally considered when using a computer program is its user-friendliness. This is a measure of how easily the users can be able to operate the computer. Some programs are more user- friendlier than others. A lot of research and effort has been dedicated in trying to come up with more user-friendly software. The ease of use of a program will most likely influence whether the user will prefer it or not.
Cost
The cost of software is perhaps one of the most controversial issues that must be considered carefully. One cannot just go for software because it is cheap. Many other factors may force a person to buy far much more expensive software even with cheaper alternatives available. However it is illogical to buy expensive software if there is a reliable cheaper alternative that will meet ones needs.
In case the off- the-shelf software does not fit the needs of the users it would be advisable to develop in-house software solutions even though they may be a bit more expensive.
Compatibility and system configuration
Software compatibility refers to the ability of the computer to run the software depending on the system setup (configuration). For example some software may only run on a computer that has 32MB of RAM and above. Any computer with lower than this, will be said to be incompatible. It is important that one reads the installation guide and system requirements that comes with the software in order to avoid disappointment.
Portability
Portability in this aspect refers to whether a program can be copied or installed in more than one computer. Although, most software in the market today are portable some developers produce software which can be installed on one machine only. This means that if one has twenty computers, one should buy a license for each.
3.1 OPERATING SYSTEMS (OS)
Chapter outline
3.1 Introduction
3.2 Resources under operating systems control 3.3 Functions of an operating system
3.4 Types of operating systems
3.5 Factors to consider when choosing an operating system
3.6 How Windows organizes information
3.7 Managing files and folders
3.8 Disk management using Windows
3.9 Installing Windows operating system
Introduction
As mentioned earlier, an operating system is the main program that controls the execution of user applications and enables the user to access the hardware and software resources of the computer. In a data processing environment, the user sees a computer as a group of application programs that enables him/her to accomplish specific tasks. Application programs do not directly utilize the hardware devices. They send messages through the operating system which has the capability to give instructions to the hardware to perform a particular task. An operating system therefore, supervises all the other programs in the computer and manages access to the hardware as shown in Figure 3.1.
3.2
Resources under operating systems control
A computer is composed of a set of software-controlled resources that enable movement, storage and processing of data and information. The resources or devices under the operating system control include: the processor, the main memory (RAM), input and output device and parts, secondary storage devices and communication devices.
The processor
The processor is a scarce resource. It executes tasks called processes. At anyone time several tasks may require processing hence creating competition. The operating system arranges the tasks according to priority and has the ability to stop a particular task to allow the processor to service another one.
Main memory (RAM)
At anyone given time so many tasks may require the memory so that they can be accessed and processed by the computer. However, because memory is also a scarce resource, the operating system determines which task will remain in memory awaiting for execution and which one will be sent back to secondary storage to wait.
Because the operating system is large and very important, it is usually installed on the hard disk but must be loaded to RAM during the booting process. Not all the operating system can fit in RAM so a small special part that contains the most necessary commands and procedures called the kernel is the one that is loaded.
Input/output devices and ports
In most cases, the operating system controls all data input and information output tasks. Because most input/output devices are slower than the processor, the operating system has to control the flow of data from the time of input to the time the user receives it as information. It ensures that the right data reaches the processor at the right time. The operating system also defines the various input/output ports found on the computer e.g. printer port.
Secondary storage devices
The operating system manages the storage and retrieval of data on secondary storage devices. It also utilizes the free space on hard disks to enhance the performance of the computer by temporarily holding tasks
on it that were in RAM ready for processing but have to wait for some time.
Communication devices and ports
Communication in this case refers to how the various devices and programs in and out of the computer system send and receive messages from one another and from the processor. The operating system controls the overall communication process between various tasks and computers. External communication can be achieved by connecting an external device to a communication port using a communication medium like cables or even wireless communication.
3.3 Functions of an operating system The functions of an operating system are:
Job scheduling
The processor can only handle one task at a time. Therefore, the operating system has to determine which task will be processed first and makes sure that the one that is currently being processed is closely monitored to avoid wasting time in the processor. The criteria for selecting which task will come before the other depends on many factors. For example, the operating system may decide to process smaller tasks before larger ones.
Resource control and allocation
In order for the processor to be able to recognize and priorities the use and requests for resources, it gives each resource a unique identification number called an interrupt number. Hence when two tasks request to use a resource at the same time, the one with higher priority interrupt is granted control. This can be compared to the priority given to the presidential motorcade on a busy road.
Secondly, the operating system tries as much as possible to avoid a situation where a particular task holds a needed resource and refuses to release it for use by other tasks. When several tasks do this, an undesirable situation called deadlock occurs.
Therefore, resource control and allocation is a core operating system function because it determines which task uses a particular resource and at what time.
Input/output handling
Every computer has many input and output devices (I/O). Like a skilled traffic officer, the operating system coordinates between these various I/O and other peripheral devices such as auxiliary storage devices, making sure that data flows properly between them and sorting out any possible confusion. For example, when printing, the CPU directs its attention to the printing function. The operating system searches for the printer, chooses the correct one, translates the name for the CPU and finally the CPU sends the document to the printer. This then makes the CPU available for other activities.
Memory management
All data and instructions must be temporarily held in the main memory before and after processing. The operating system may organize the main memory into blocks of sizes called partitions. It constantly assigns main memory storage partitions to data and instructions. To access a piece of data or instruction, the operating system knows where to find each piece of data as long as the correct address of the partition is used.
Error handling
The operating system has many ways of alerting the user, of errors he or she makes. Many op rating system usually express what the error is, and where possible make suggestions on how to correct the error. The operating system does this by monitoring the status of the computer system and performing error checks on both hardware and the software.
Job sequencing
The operating system keeps a list of jobs or tasks currently being run and clocks them in and out of the processor. It also arranges them in a particular order to make it easy for the processor to execute them and to know how and when to fetch instructions and data for each task.
Interrupt handling
An interrupt is a break from the normal sequential processing of instructions in a program. An external request causes the processor to stop executing the current task, and do something else before returning the control back to the program that was interrupted.
Each hardware device communicates to the processor using a special number called the interrupt request number (IRQ number). Fig 3.2 shows the devices assigned to IRQ numbers in Microsoft Windows.
3.4 Types of operating systems
Operating systems can be classified according to:
Classification according to tasks handled concurrently
Single program operating system
Single program operating system allows processing of only one user program in the main memory at a time. This means that the user can only run one interactive program at a time. Then the user must exit from the program before loading and running another program. An example of a single user operating system is MS DOS from Microsoft Corporation.
Multi tasking operating system
This type of operating system allows a single CPU to execute what appears to be more than one program at the same time. However, internally only one program is being executed at a time. The CPU switches its attention between programs as it receives requests for processing, executing statements from one program, and then from another using the concept of giving a time slice to each application. This switching of attention is so fast that it appears as if the programs are being executed simultaneously.
Classification according to number of users
Single user operating system
A single user operating system is designed for use by only one person. It cannot support more than one person and runs only one user application at a time.
Multi user operating system
Multi user or multi access operating system allows more than one user to interactively use the computer. It can be installed on a computer that is accessed by many people at the same time. Examples of such operating systems are UNIX, Novell and Windows NT/2000, Linux.
Classification according to interface
The term human computer interface refers to the method of interaction between the computer and the user and determines how easily the user can operate the computer. The underlying principle in operating system design is to make complex tasks very simple for the user to carry out. This is the reason why a lot of time has been spent by software developers in trying to come up with user friendly interfaces.
Currently the three main types of human computer interface are:
Command line Interface
The user interacts with a computer by typing a command at the prompt found on a command line. A computer reads instructions from the command line and executes them. For a command to be more user friendly, the words used should be descriptive verbs e.g. print, copy etc. Unique abbreviations can also be used e.g. Del Ren Chkdsk etc.
For example, if you are using MS DOS operating system, you can copy a file called Fruits.Dat from a hard disk C to floppy disk A as follows: COPY C:\Fruits.Dat A:\
NB: The user must press the enter key for the command to be executed.
Examples of command line interface are the early versions of MS DOS, PC DOS, OS/2, and UNIX.
MS DOS Interface
Menu driven interface
This type of interface provides the user with a list of options to choose from. The interface therefore is suitable for beginners who may have difficulties recalling commands.
Some operating systems present the user with simple menus while others have sophisticated menus.
The user makes a selection `by typing any of the letters I, V, E, D or Q to activate a submenu.
A menu driven interface.
Later versions of DOS came with a menu driven interface called the DOS shell or DOS editor
Menu
The DOS shell
The graphical user interface (GUI)
This type of interface represents commands as small pictures on the screen called Icons. Icons can be selected to issue a command using a pointing device like a mouse. GUI has become a very common type of interface because of its user friendliness.
Examples of GUI based operating systems are OS/2 s Presentation Manager, Microsoft Windows, Linux and Apple Macintosh.
3.5 Factors to consider when choosing an operating system
When choosing an operating system for a computer, the following factors should be considered:
3.6 How Windows organizes information
Introduction
Microsoft Corporation is a software company that specializes in the development of both operating systems and application programs. Some of its popular operating systems include; Windows 95, 98, 2000, NT, Millennium (Me) and XP. These operating systems have gained wide popularity with many PC users because of their friendly graphical user interface.
Other operating systems that rival Microsoft products include Linux, UNIX, Mac OS and OS/2.
NB: In order to understand how an operating system organizes information, this book cuts across four versions of Windows i.e. Windows 95, 98, Me and XP, by giving standardized procedures that are common to all. However because it is hard to cater for the small differences in the four versions, the book provides a common procedure of carrying out Tasks. However, extra details on specific versions are discussed in appendices L II and III.
The good thing about all the versions of Windows discussed in this book is that once you acquire basic skills in using one version, you can easily transfer the same to other versions.
Some common features in Windows operating systems:
Windows manages data and information stored on secondary storage devices by organizing it into easily accessible units called files and folders.
Files
A file is a collection of related data or information stored in one location and given a unique name that enables the operating system to identify it during storage and retrieval process. Every file has details that indicate the following:
There are two types of files namely; system file andapplication files.
System files
These of files contain information that is critical for the operation of the computer. For example, all hardware devices are tested and made ready (initialised) during boot up by having the computer read information
From special system files. These files in Windows would have name extensions like .sys, .ini and .dll. An example of a system file is system.ini
Application files
They are also called program files because they hold programs or application files. They may have extensions such as .exe.
The following list gives some common file name extensions and suggests the type of information that could be held in the file.
Extensions Type of information
DAT Data files
EXE Executable file that starts an application
TXT Text files
DOC Document file
When naming files, it is important to give meaningful names and extensions that suggest its content. For example when saving a letter written to John, give it a name such as Johnletter. The name extension is automatically added by the application being used.
Folders
A folder or a directory is a named storage area where the user can store related files to enable easy access. Like with an ordinary file cabinet, a folder is meant to help the user divide a large storage media into small manageable storage locations.
Subfolders
A large folder may be divided into smaller units called subfolders. Therefore, a subfolder or subdirectory is folder/directory within another folder/directory.
In Windows, folders and subfolder icons mostly appear in yellow color while file icons are mostly white with a fold at the top right hand corner
Storage media
When saving a file or creating a folder, identify a storage location, which is more reliable and sufficient. For example, if a file or folder requires more than 1.44MB of storage space, you can not use a 1.44MB 3 inch. floppy disk instead use a storage media with larger space.
Windows desktop
Once you switch on the computer, Windows is automatically loaded into the main memory and a mostly empty screen called the desktop appears. This shows that the computer is ready for use.
Some versions of Windows e.g. Windows XP, prompt the user to press Ctrl +Alt +Delete to gain access to desktop features through a process called Log on.
Desktop features
On the desktop are icons and a long thin bar called the task bar. Figure 3.8 shows a Windows Me desktop.
Icons
Icons are mostly manipulated using a pointing device e.g. the mouse. Some of the common icons on the desktop are My Computer; Recycle bin, Internet Explorer, and My Documents.
The task bar
The taskbar enables the user to easily switch between different programs and documents (tasks) that are currently running.
Whenever the user starts a program or opens a file, its button appears on the taskbar and stays there until the user exits from the program see Figure 3.9. You can switch between various programs and documents in Windows by clicking these buttons. This process is called multi tasking.
The taskbar has at least three main parts.
Start button: The leftmost button on the taskbar that the user clicks to display the start menu.
Task manager: This is the plain stripe that displays buttons of all currently running tasks. The task manager of Figure 3.9 shows OPERATING SYSTE is the currently running task
System tray: This is at the right most part of the taskbar. It has icons of tasks running in the background put are not displayed on the screen. Examples are the time and calendar, an antivirus program, volume control etc. To display such a task, simply double click its icon.
The start menu
When you click the start button, a list of choices appear called the start
menu. The items on the menu may vary depending on the version of Windows you are using. Figure 3.10 (a) and (b) shows Windows Me and Windows XP start menus respectively. From careful study of the figures, you will notice slight variations but most commands on the menu items remain the same.
Programs
This menu displays a list of all programs installed in the computer. The menu has a small solid arrow. When you point at it, another list of menus called a sidekick menu will be displayed as shown in Figure 3.10 (a) and (b).
Documents / my recent documents
Documents menu in Windows 95, 98 and me or my recent documents in Windows XP lists the last fifteen recently accessed files. You can open any of the listed files from a storage device by clicking its name provided that the device is accessible.
Settings / control Panel
Settings menu in Windows 95,98 and Me or the control panel in Windows XP provides tools which the user can use to maintain and make changes to the computer setup. It is important not to tamper with this menu because you may interfere with the computer functionality.
Find / search
Find in Windows 95,98,and Me or Search in XP helps the user to search for a file or folder in case the user forgets its name or location.
Help / help and support
The help command on the start menu, displays detailed information on how to use the operating system and solve some computer related problems in case of the computer fails to function properly.
Run
It enables the user to:
Log on / log off
Log on is a security measure that restricts unauthorized uses from accessing computer resources. It prompts for a user name and password in order to gain access. After using the computer, log off the computer before leaving.
Shutdown
This menu lets the user shut down, restart the computer, or restart in MS-DOS mode. Windows Me and Windows XP do not have MS-DOS in their shut down dialog box, see appendix II and III.
Every time you finish using the computer you must first shut it down before turning it off. To do this you need to:
3.7
Managing files and folders
To manipulate files and folders, you can either use My Computer icon from the desktop or Windows explorer from the start menu. Each in its own way lets you see how storage devices or locations, files and folders are arranged. These tools also enable the user to manipulate files and folders.
Windows explorer
Windows explorer lets the user display the drives and folders in a hierarchy or tree structure. The computer tree is an up side down structure with the highest level being the root. The explorer divides the window into two panes. The left pane displays a tree of drives and folders while the right pane displays a list of files and sub folders contained in a particular open drive or folder.
To display the Windows explorer in some versions of Windows like 95/98 carry out the following procedure:
An explorer window such as the one shown in Figure 3.12 will be displayed.
NB: In some operating systems, Windows explorer command may not necessarily be located on the program s menu. The other method of displaying the explorer window is to:
This method of displaying the explorer window has been adopted as the standard way of displaying the explorer window throughout this book to take care of various versions of Windows operating systems.
In Figure 3.12, the highest item in the tree is the desktop then followed by My Computer. If you observe keenly, you will notice that some items have a small box on their left with a plus or minus sign inside. If an item has the plus sign on its left, it contains other lower level items e.g. My Documents folder in the above figure, has subfolders inside. To display the subfolders, click the plus sign and the sign will change to minus meaning that all subfolders in that level have been displayed. You can reduce (collapse) the tree by clicking minus sign.
Using My computer
Double clicking on my computer icon, gives you a graphical view of what is inside the computer. This includes the drives, the control panel and other resources as shown in Figure 3.13 (a).
To display files and folders from a particular drive proceed as follows:
4.
Creating a new folder
There will be times when the user would want to create new folders. Say, for instance, when working on a detailed project that has multiple files. It is advisable that all related files be kept together in one folder. To create a new folder proceeds as follows:
NB: To create a subfolder, follow the steps above but select a folder as the location. To open a folder proceeds as follows:
Creating a new file .
Depending on the programs installed in your computer, you can create files of different types such as drawings, text document etc. To create a new text document proceed as follows.
NB: In Windows, file names can contain up to 255 characters, including spaces but, with no special symbols such as \ /: *? <> I.
The application Window
In order to enter data in the new file just created above, you have to open it in its application program. This can be done by double clicking the file icon. A rectangular area called an application window appears on the screen as shown in Figure 3.15.
Parts of a Window
Title bar
This is a bar across the top of the window that displays the name of the current application program or task.
On the right of the title bar are three tiny buttons namely:
Minimize button: It reduces a window by pressing a button which is placed on the taskbar.
The restore/maximize button: It stretches the window to cover the entire desktop or restore it to its original size.
The close button: It is used to exit an application.
Menu bar
Menu bar provides a list of commands that can be used to manipulate a task. For example, to save a document, click file and then save.
Too/bars
These are buttons arranged in a row that are shortcuts to menu commands.
Work area
This is the working area where you can create your documents.
Status bar
This is an interactive strip at the bottom of the application window that acts as a communication link between the user and the operating system. Such interactive activities include saving, opening a file, printing, cursor position etc.
Scroll buttons and arrows
Scrolling is the moving up, down, left or right of a document window on the screen if it is too large to fit. Scroll buttons and arrows are horizontal and vertical buttons at the borders of a window used to scroll through long document.
Saving changes to a file
After typing the content of the file in the work area, click file and then Click save Otherwise, if the file will be saved with a different name or location then:
Renaming files or folders
Renaming refers to changing the previous name to a new name.
To rename a file or a folder proceed as follows:
Deleting files and folders
In Windows, when you delete an item from the hard disk, it is temporarily held in a special folder called the Recycle bin from which it can be restored if necessary.
The recycle bin is a default icon on the desktop therefore it cannot be removed.
Warning
To delete a file or folder proceed as follows:
Restoring deleted files and folders
To restore a file or folder from the recycle bin to its original location proceed as follows:
Emptying the recycle bin
To completely discard files and folders you deleted, you need to empty the Recycle Bin. Deleted items take up the same amount of disk space they occupied before you deleted them. To free up that disk space occupied, you have to empty the bin.
To empty the recycling bin proceed as follows
NB: You can also delete selected items in the recycle bin by clicking file then delete
Copying and moving files and folders
Cut or copy commands are used to move or create a duplicate of an item respectively. When you cut or copy an item, it is temporarily held in temporary storage location known as the clipboard. To copy a file or folder:
Copy progress dialog will be displayed on the screen as shown in Figure 3.16 below
To move a file or a folder proceed as follows:
Sorting files and folder
Sorting means arranging files and folders in a particular order either alphabetically or by size or date of last modification or creation. Widows automatically sorts files and folders into alphabetic order but the user can choose to arrange them otherwise. For example Figure. 3.17 show how to sort by name. Notice that a dot appears next to name to show that it is selected.
Manipulate files and folders using the shortcut menu
When you right click an item, a shortcut menu is displayed which provides commands commonly used to manipulate the item.
To copy, move, delete or rename an item proceed as follows:
(a) To copy or move, right click the destination location then click paste
(b) To delete, simply click delete Command.
(c) To rename, type in a new file name to replace the old one.
Manipulate files and folders by drag and drop
Another easier method of handling files and folders is drag and drop. This is done as follows:
Selecting multiple files and folders
If you want to manipulate multiple files or folders at a go, you can select them by clicking each item while you hold down the control (CTRL) or SHIFT key.
If you want to select all files in an open folder, click edit then select all. This will highlight all files in the folder. To manipulate the selected items, use the menu bar or the shortcut.
Searching for files and folders
To search for a specific file ‘or folder proceed as follows:
Windows 98 find dialog box.
3.8
Disk management using Windows
Windows operating system provides the user with tools that help him/her to manage storage devices and media. It is important to have a routine check of all the storage devices otherwise one may end up losing very vital data and programs.
Warning: Do not attempt these operations on disks without the guidance of the teacher. It is preferable to use the floppy disk rather than the hard disk to perform these operations because some of them can easily lead to loss of data and information stored on the hard disk.
Formatting disks
Before using a floppy disk, it must be formatted. Formatting is the process of preparing a new disk for use by imprinting empty sectors and tracks on the surface of the disk so that the operating system can recognize and be able to access it. Most diskettes today are sold readily formatted. Each operating system has its own special way of formatting a disk that may make the disk not to be read by another operating system. To format a new floppy disk proceed as follows:
Scanning a storage device for problems
Windows has a disk management tool called the scan disk that helps the user check up and repair minor storage problems, such as lost storage locations, or damaged surface. To scan a storage device the following is done:
Using disk defragmenter to rearrange storage media content
Disk defragmenter is a tool that is used to rearrange scattered folders and files on a storage media in order to speed up access to files and folders. This enables the read/write head not to waste time looking for the same item all over the disk. Figure 3.20 shows a disk before and after defragmentation. Notice that the fragmented disk has related data elements spread all over it but the defragmented one has related data consolidated close to each other.
To start disk defragmentation proceed as follows:
1.Double click my computer icon to display the storage devices installed on the computer.
Compressing the storage media
Windows provides the user with two compression tools namely, compression agent and DriveSpace. Compressing storage media contents to fit in smaller space helps to create more free space on the media.
DriveSpace can use the free space on an uncompressed drive to create. a new, empty compressed drive called a host. To compress a disk proceed as follows:
3.From the shortcut menu, properties If you are using windows XP select the Compress drive to save disk space, check box then click ok as shown in Figure 3.21 (a). If using windows 98 click the compression tab then click compress drive button. (Figure 3.21 (b))
NB: If you are using Windows 95/ 98, click the start button, point to programs, accessories, then system tools and select compression agent or DriveSpace.
From the compress dialog box, click drive then compress
Scanning for viruses
A computer virus is a program written by malicious persons aimed at conducting unwanted operations like damaging disks and data. Severe virus attack can result in system failure. There are literally thousands of these evil programs that can get into a computer via infected floppies or even via electronic mail and the Internet.
Cleaning infected storage devices
To guard a computer against virus attack, special programs called antivirus software such as Norton Antivirus, PC-cillin or McAfee should be installed on the computer. These programs can check your system for thousands of known viruses and eradicate them. To scan for viruses the following is done:
Backing up Data
Windows comes with a utility called backup. It enables the user to create copies of data and programs (on separate storage device) to avoid losing important data and program files in case the storage device or the computer fails. It is good practice to keep backups away from the computer room to ensure security of the information in case of a calamity such as fire. To create a back up proceed as follows:
Restoring backed up data
To restore backed up data proceed as follows:
The startup (Boot up) disk
Suppose the hard disk is seriously damaged, and the computer cannot start Windows. The only other option available would be to start the computer using a startup disk that has booting instructions. The start up disk is usually a floppy disk that was created using the operating system.
To create a startup disk
To boot up a computer using the start up disk insert it in the floppy drive then switch on the computer. The computer reads the boot up instructions from the diskette then displays a command prompt such as A:>– that enables the user to type commands. The commands help the user diagnose the problems that might have led to boot failure.
Partitioning a disk
Partitioning a disk refers to the process of dividing a large physical disk into two or more partitions called logical drives. A logical drive is a drive that can be accessed as if it is a separate disk but in actual sense, it is a partition of one large physical disk.
Reasons for partitioning a disk The reasons are:
Partitioning process
To create partitions, you must have a startup or bootab1e diskette and proceed as follows.
(a) Choose option 1 to create primary DOS partition that will be treated at the bootab1e disk or drive C.
(b) Choose option 2 to create extended (other) DOS partitions.
(c) Choose option 3 to give your extended DOS partitions drive labels.
Once you finish partitioning the disk, reboot the computer for the changes to be effected then format the drives created. If you do not format the drives, the computer will not be able to access the storage media.
NB: You can also use the other FDISK options to display partition information or Delete partitions.
3.9 Installing Windows operating system
Installing Windows 98
Because the operating system is the supervisor for all the other computer programs it must be installed into the computer s hard disk before installing any other program.
The term installation refers to the process of copying program files onto the hard disk. Installation differs from copy paste process in that it is specifically meant to copy executable files in a format that allows the computer to run the program.
To correctly install an operating system, carefully study the manufacturer s documentation (manuals) in order to get the correct information on installation procedures and system requirements. For example to install Windows 98, Microsoft recommends that a computer should have the following minimum requirements:
This configuration would work but a Pentium I and a machine with
32MB of RAM and above would be much better.
Installation process
In order to install Windows 98 on a computer that does not have an operating system, the user must have a Windows 98 Startup disk. This disk gives the user options for loading with or without the CD-ROM support.
Because Windows 98 comes on a CD-ROM, you must boot the computer With CD-ROM support in order for the computer to recognise the CD-ROM drive.
A successful boot displays the prompt; A :>-‘ Then
The prompt should change to the letter that was typed to represent the CD drive e.g. D: \>
This means that the computer is able to read whatever is in the CD-ROM drive.
First Setup scans the available disks for errors and if an error is encountered, it is fixed but if it is more serious, the setup process is halted.
After this, the setup program (Wizard) asks you a few questions, gets you accept the license agreement and enter the product key. See Figure 3.24.
The rest of the installation is automated. All you need to do is just relax and let the wizard complete the installation task.
Troubleshooting Windows related problems
The term troubleshooting refers to the process of diagnosing and trying to fix (resolve) hardware or software related problems. When using
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Windows, you may experience some problems such as;
error has occurred etc.
These problems may be due to one of the following reasons:
Himem.sys (device drivers in Windows that helps in allocation of main memory)
To resolve these problems you need to:
This will help you to check whether the problem is due to disk failure or corrupted registry. With safe mode, you can establish whether the problem is due to corrupted system registry or failed devices. If the registry has failed, the computer will prompt you to reinstall the registry backup. If the problem is due to disk failure, start the computer using the start-up disk and type Scandisk C: at the command prompt. Scandisk will establish whether the failure is due to bad file or directory structure or damaged disk surface.
APPENDIX I
Beyond basics
Arranging multiple application Windows on the desktop One of the biggest advantages of multitasking is that one can open and work with several applications. One may wish to arrange open Windows either, side by side (Tile) or one on top of another (Cascade).
Tiling windows
Tile horizontally
This arranges all running programs one below the other as shown in Figure AI.I. The program in focus will have its title bar highlighted. To switch to another program, simply click its title bar. To tile horizontally:
Fig. A 1.1: Tiling horizontally
Tile vertically
Applications can be arranged down the screen beside each other as shown
in Figure AI.2. To tile vertically:
Undoing tile
You can undo tiling by right clicking the from the shortcut menu.
then click
Cascading
Each window is placed on top of the other with the active program being foremost as shown in Figure A1.3. To cascade:
Undoing Cascade
You can undo cascade by right clicking the taskbar, then click undo cascade from the shortcut menu.
Customising common features in Windows 98
Customising the desktop
Windows lets the user change desktop appearance and display.
To customise the desktop, right click the desktop to display properties dialog box as shown in Figure A.1.4 and make the appropriate changes by clicking each tab.
The background
To set the background
Setting the screen saver
If the screen saver is set, it starts playing on the screen if the computer is left idle for a set period of time.
To set a screen saver:
NB: To clear the screen saver press the mouse button or any keyboard key.
Changing the screen appearance
This will change the appearance of Windows items such as icon size, border colours, highlights etc.
To change the screen appearance:
Set Windows items effects
With Windows 98, the user can change icon type as well as visual effects of most of items such size of icons, animate windows, and menus among others. To set Windows effects:
Web
With Windows 98 you can customise the desktop by integrating the Web
features on it. You can also turn the Web elements into desktop elements and update them at any time, this is done by:
Setting display colours and resolution
The clarity of an object depends on color intensity and resolution of the display unit.
To change color and resolution settings
Setting date and time
To set date and time:
Mouse settings
To change the default mouse button, double click speed and the pointer appearance to set a mouse:
APPENDIX III
Windows Xp desktop feature
They re some slight changes on how some icons appear and their labeling on the desktop as shown to enhance security, the user has to log on by pressing Ctrl + Alt + Del keys in order to use the computer resources.
The start menu
The start menu layout is slightly different from that of Windows 95, 98 and Me. The start button displays a pane divided into two. The control panel has replaced the settings menu while the shut down and log off commands can be accessed on the start menu as shown in Figure A3.2
Changing desktop properties
To change desktop properties:
Shutting down the computer
Simply click the start button to display the shut down dialog box similar to the one shown in FigureA3.4. As with Windows Me, in XP one cannot also restart in MS DOS mode. New commands such as log off Administrator and Hibernate have been introduced.
APPENDIX IV
Glossary
Access time: The length of time needed to write or read data from storage.
Application package: It is a program that is used in processing user specific needs sometimes called off-the-shelf or canned programs.
Arithmetic and Logic Unit (ALU): A part of the central processing unit that performs computations and makes comparisons as instructed.
Artificial intelligence (AI): A field of computer technology in which researchers and electronic product developers concentrate on developing computers that imitates human intelligence.
Bits (binary digits): Since digital computers and computer accessories circuitry represent data as a pattern of on and off state of electric current, a bit is a 1 or a 0 used to represent the two states respectively.
Byte: A group of bits used to store a single character. A byte usually consists of seven or eight bits, which the computer handles as a unit.
Central processing unit (CPU): This is the brain of a computer, which apart from performing processing tasks; it controls all other activities of a computer system.
Computer hardware: The physical computer equipment one can see and touch. Such equipment includes the system unit, input devices, storage devices and output devices.
Computer program: A set of instructions that direct the computer what tasks to perform and how to perform it. These instructions are specially written using a computer programming language.
Computer software: See computer program
Computer system: A computer system refers not only to the physically attached devices to the computer but also to software and the user.
Control unit: The part of the CPU that interprets the instructions and controls all the operations in a computer system. The control unit monitors on the input, storage, the arithmetic and logic operations, and the output operations to have the instructions carried out.
Data: This are the raw facts represented by numeric, alphabetic characters and special symbols that are processed into information by the computer.
Data processing: The varied activities performed to convert data into useful information.
Desktop publishing: The process of designing and creating professional documents such as books, magazines, brochures and cards using specialised software such as PageMaker, which instructs the computer to size, insert, graphics as well as print a document.
Direct access: The ability to go directly to the storage location for the particular data required for processing, without having to search through all the records from the beginning of the file.
Drive: Devices used to read and/or write (store) data on a storage media.
Electronic mail (e-mail): A type of mail system that uses computers and the telecommunication facilities to transmit messages. Messages may be in the form of letters, memos, reports, or graphic displays.
Electronic spreadsheet: Computer software that has rows and columns used for doing a number of calculations and forecasting future trends.
Floppy disk: A floppy disk or simply a diskette is made up of a small flexible disk coated with iron oxide. This disk is covered with a plastic protective case. It is portable thus making it the most common type of storage device used with microcomputers.
Hard copy: Hardcopy refers to the tangible output produced mostly on a piece of paper by devices such as printers and plotters.
Hard disk: Also referred to as a hard drive or a Winchester disk, is a sealed unit in which are shiny, metallic disk platters and read/write heads that reads and records data on the disks.
Information processing cycle: The full set of operations that take place, from collection of input data to the availability of output (information).
Input: A collection of raw data at the start of information processing cycle.
Input/output (I/O) devices: Devices used for entering data to be processed and for reporting the results of processing.
Integrated circuits: Thousands of small circuits etched on a silicon chip. As these circuits are made more and more compact, they are called Large Scale Integrated (LSI) and Very Large Scale integrated (VLSI) circuits.
Menu: A program s list of user choices or possible actions usually shown on the screen. Choices are usually expressed in simple language statements for ease of use.
Microcomputer: The name given to a small, low cost computer system with a microprocessor as its brain. A microcomputer can perform input, processing, storage and retrieval, and output operations rapidly, accurately, automatically, and economically despite its relatively small physical size.
Microprocessor: A complete central processing unit of a computer placed on a single Large-Scale Integrated (LSI) circuits chip.
Minicomputer: A computer having a smaller capacity for both primary and secondary storage than medium size and large size mainframe computers.
Networks: Communication systems that connect computers, terminals, and other electronic office equipment for the purpose of efficient communication and sharing of resources.
Operating system: This is a complex program that is responsible for controlling processing operations in a computer system. It handles input, output, storage and running of other user programs. Examples of common Operating Systems are Microsoft Windows 95/9812000/XP, UNIX and Linux, Apple Mac OS etc.
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Optical disk: These are disks on which data is recorded using a laser beam (a very strong concentrated light). The beam bums the thin shiny reflective surface to record data.
Output: Useful information available at the end of the information processing cycle.
Plotter: One type of graphics printer used to provide hard copy of graphical output. The output appears in such forms as multicolored charts, graphs, diagrams and maps.
Random-Access Memory (RAM): A type of main memory that holds data and information temporarily before and after processing. It is called random access memory because the data contained in each storage address can be directly retrieved without regard for the sequence in which it was, stored.
Read-Only Memory (ROM): The other type of main memory with data or instructions permanently or semi permanently recorded in it. This means that no new data can be transferred in to ROM during processing. ROM is used to store program instructions that the computer always needs to operate. ‘
Robotics: The use of robots controlled by computer to perform work ordinarily done by human beings. Robots usually have computer controlled arms and a control camera placed inside that enables it recognise different objects.
Scanner: An input device that captures data from source documents and objects.
Semiconductor: An electronic component consisting of small chips of silicon on which integrated and support circuits are etched. It is used for developing microprocessors, primary and other electronic components.
Storage: The storing of data and information for future us. The length of time the data is stored can vary from less than a second to months or even years.
Supercomputer: The largest, fast, and most expensive type of computer available. They can perform hundreds of millions of complex scientific calculations in a second.
Utility program: A collection of instructions designed to make common processing operations run smoothly.
Volatile memory: The term applied to semi-conductor memory because its content is lost when the electric current is turned off. The content must be stored on an auxiliary storage if it is to be used again.
Word processing: The processing of textual data to produce documents such as letters, reports, manuals, catalogs, newspapers, magazines, books or other documents.
FORM TWO NOTES
WORD PROCESSORS
Chapter outline
1.4 Editing and formatting a document.
1.5 Creating and editing a table.
1.6 Mail merge document.
1.8 Printing a document.
Definition of a word processor
What is a word processor?
A word processor is an application software that enables a person to create, save, edit, format and print text documents. Word processing is the act of using a word processor.
Examples of word processors
Examples of word processors include, Microsoft Word, Corel WordPerfect, WordStar, Lotus WordPro and many others.
A word processor has a number of advantages over he type writer that include:
Basic word processing features and concepts
(a) Most are designed to look like a piece of paper with a few
(b) Most of the screen is blank before typing of text.
(c) There is a cursor, which blinks at the position where you can Begin entering text.
(d) There is a status bar or line that provides the user with current status information such as saving operation, the name of the file in use, the current page, the current imaginary horizontal-line and column cursor position.
(e) Word wrap: The feature that automatically moves a word or cursor to the beginning of the next line if it does not fit at the end of the current line.
(g) Scrolling: This is the vertical movement of text document on the screen. We can scroll through a text document using the up or do n arrow keys, page up and page down keys and also using, a mouse in windows based word processors.
(h) Help: Sometimes we get lost, confused or need more information on how to use an application. Help contains instruction, tips, pointers, explanations and guidance. You can get help by either pressing F 1 on the keyboard or clicking Help from the menu.
(i) Editing Modes: Word processors have two editing modes, insert and type over mode. In insert mode, every character typed between words, lines or characters is placed at the cursor position. This pushes all the text in front of the cursor away without deleting it. However in type over mode every character typed deletes what was there before and replaces it with new text at the cursor position.
Mostly, word processors are used for writing letters, reports, projects, books, essays, memos curriculum vitae etc.
Factors to consider when choosing a word processor The choice of a word processor depend on:
Using a word processing package Microsoft Word
.
Microsoft Word is one of the components of Microsoft Office. Microsoft Office is integrated software with a number of interrelated programs. The programs include Microsoft Word, a spreadsheet called Microsoft Excel, and a database management system called Microsoft Access, communication software called Microsoft Outlook, and a presentation package called Microsoft PowerPoint among others.
Although there are several versions of Microsoft Word, the most common are Word 97, Word 2000, WordXP and Word 2003. These versions of Microsoft Word are found in Microsoft Office 97, 2000, XP and 2003 suites respectively.
Starting Microsoft Word
There are a number of ways you can start Microsoft Word. However the
Simplest is by using programs start menu.
Starting Microsoft Word from the start menu
Microsoft Word screen layout
Once you start Microsoft Word, it provides you with a blank document window referred to as the new document template where you can create your document.
However you may need to use other specialised templates such as Faxes and letters, Memos and Web page. How? Click File then select New from the menu. The New dialog box in Figure 1.3 that appears enables a person to select a template by activating templates tab then double clicking its icon.
With Windows multitasking capability, you can have more than one document window at the same time sharing one application window. However, each document window will have its own title bar but both will share other facilities like the menu bar of the application window.
However only one document window will be visible on the desktop at a time while others remains minimized or covered. This window is referred to as the active document window. To switch between document windows, click their buttons on the taskbar.
Parts of a window
Title bar
A title bar is mostly a blue strip at the top of the window that displays the title of the currently running application or task. However it is possible to change the color of the title bar using the display properties.
The title bar also enables the user to move the window around the desktop. This is possible by pointing to it then dragging using the mouse.
On the right of the title bar are three tiny buttons called minimize, restore/ maximize and the close buttons.
The minimize button reduces a window to become a button on the taskbar.
The restore/maximize button stretches the window to cover the entire desktop or restore it to its original size respectively.
The close button is used to close and exit a window.
Menu bar
Provides a drop down list of commands that one can use to perform a task. Examples are File, Exit, Window and Help. Figure 1.4 shows the File drop down menu.
Too/bars
These are rows of buttons or icons that represent commands. The command buttons are shortcuts to the same commands you can access from the menu bar. There are various toolbars available in Microsoft Word but the most common are the Standard and Formatting toolbars (Figure 1.5 and 1.6)
To see what other commands are, just point to the icon on the toolbar and a text tip will be displayed showing the function of the icon.
Most of these commands will be discussed later.
Hiding and displaying the toolbars
Selected toolbars have ticks or check marks next to them as shown in Figure 1.7.
Rulers
Microsoft Word provides the user with vertical and horizontal on screen rulers that helps the user position text or objects in the right position.
If the ruler is not visible on the screen, then display it using the following procedure.
Work area
This is the working area where you can enter text or graphical objects. All windows based application programs provide the user with a unique working area suited to that particular application.
Status bar
This is an interactive strip at the bottom of the screen that acts as a communication link between the user and the program. It displays interactive activities like saving, opening, background printing, cursor position etc.
Scroll bars/button_ and scroll arrows
Scroll bars or buttons are horizontal and vertical bars on the borders of a window that the user drags to scroll upward, downwards, to the right or left of a document. Scroll arrows are arrows at the end of the scroll bars that the user clicks instead of dragging the scroll button. Using scroll bars or arrows is equivalent to using the arrow keys on the keyboard
Running the program
Creating a document
When you start a new document, you will see a blinking vertical bar called an insertion pointer. You can move your insertion pointer by using the arrow keys or the mouse.
In case you are in Microsoft Word and you want to create another new document, you should proceed as follows:
Saving a new document
2.In the file name box, type a unique name for the document
3.Select a the location or drive you want to save in, by clicking the down arrow on the right of save in list box,
4.To save the file in a different format or type such as Word 6.0, Word for Macintosh etc. click the down arrow on the right of Save as type list box and choose a file type.
5.Click the save button. The file will automatically be saved as a Microsoft Word document.
Opening an existing document
1.From the file menu, click Open command or on the Standard toolbar, click the Open button. Alternatively press Ctrl + 0 key combination on the keyboard. The Open dialog box shown appears.
2.Select a drive or folder where the file is saved.
3.In the file name box, type or select the name of the document you want to open.
4.Click the open button
To open a document created in another program, click the file format you want in the files of type box, and then double click the document name in the folder list. You can also use wildcards in the file name box for example, type *. Document to find Microsoft Word files.
NB: Microsoft Word keeps a list of shortcut links to recently used files on the file drop down menu. If the list of recently used documents is not displayed, you can configure Microsoft Word to be displaying them by doing the following:
Protecting a document with a password
A password is a combination of characters that prevents other users from opening and changing a document without permission. If a document is protected by a password, only the person who knows the password can open the document or edit it.
To save a document with a password
Closing a document
Closing a document means unloading the current active document from memory so that the user can create or open another without necessarily exiting from Word.
To close a document:
Exiting from Word
NB: You can exit from Microsoft Word by pressing Alt + F4 keys or by double clicking the application icon at the left most comer of the title bar. If you have not saved any of the open documents, Microsoft Word prompts you to save the document first.
1.4
Editing and formatting a document
Editing
Editing refers to making necessary changes to an existing document. Apart from manual editing using delete, insert and overtype/overwrite commands, Microsoft Word provides the user with inbuilt tools such as the spelling and grammar checker, thesaurus, undo and re-do, find and replace etc.
Block operations
Selecting (highlighting) a block of text
The purpose of selecting text is to enable the user perform a number of editing or formatting operations on the selected block of text. Microsoft Word presents the user with a number of ways for selecting a block of text. You can either select a block of text using the mouse or keyboard.
Selecting with a mouse
Selecting with the keyboard
3.To select an entire page; press Shift+Page Down or Shift+Page Up. 4. To select the entire document, press Ctrl+A or place the cursor at the beginning of the document then press Shift+Ctrl+End.
Deleting text
To delete a block of text
Restoring deleted text
To restore text that has just been deleted in the current word processing session: click the Edit menu, then the Undo command
Copying and moving text and objects
Copying means creating a duplicate of text or an object while moving means changing the position of text or an object in a document. In Microsoft Word, you can copy or move a block of text.
To copy a block of text:
NB: To use the keyboard shortcut keys, press Ctrl + C to copy, then Ctrl + V to paste
To move text and objects
NB: To use the keyboard shortcut keys, press Ctrl + X to cut, then Ctrl + V to paste
Typing modes
There are two typing modes in a word processor that assist the user in typing or editing text documents. These are:
Insert mode
This is the default mode in most word processors. In this case when text is inserted between words or characters it pushes the existing text away without replacing it.
Typeover mode.
In this case, when text is typed between existing words or characters, the new text automatically replaces the existing text by deleting it. To switch between typeover and insert mode, simply press the insert key on the keyboard or double click the OVR label on the status bar.
Find and replace
When you need to search for a word or phrase in a large document, use the Find command. In case you wish to replace a word or phrase, use the Replace option.
Find
NB: You can use the keyboard shortcut Ctrl+F to find. Some search options:
You can specify search options by clicking the more buttons to display them. They include:
Replace command
Click Edit menu then Replace command. The dialog box appears.
Type the name you want to replace in the Find what box and the one that will replace it in the Replace with box. Click the Find next button to find the next occurrence of the word then click Replace button to replace it. To replace all the occurrences of the word in the document at once, click the Replace all button.
Proofreading
Proofreading refers to checking whether the document has typographical or grammar errors. Microsoft Word has tools for proofreading e.g. spelling and grammar checker, Thesaurus, Autocomplete and Autocorrect.
Spelling and grammar checker
The spelling and grammar checker is an inbuilt tool that helps the user to correct spelling errors and incorrect grammar structures. However, the checker can only recognise errors of those words whose correct spelling is in its dictionaries. A correctly spelt word used wrongly cannot be detected hence the document should be proofread just before and after printing. To check the accuracy of spelling and grammar:
And grammar checker dialog box appears as shown in Figure 1.14.
Words that do not match in the custom dictionary are highlighted for correction. The lower plane of the dialog box suggests to the user with a list of suggested correct words.
(a) Change to correct only the highlighted incorrect word.
(b) Change all to correct all the occurrences of the misspelled word.
(c) Ignore to retain the highlighted and continue. For example, although a word like jembe may not be in the custom dictionary, in the Kenyan context, the word is acceptable therefore if highlighted, click Ignore.
(d) Ignore all to retain all the occurrences of the same word or phrase in the document from another language e.g. a Kiswahili
(e) Click Add to add the word into the custom dictionary.
In case you want to undo the changes made, click on the Undo button at the lower bottom of the spelling and grammar dialog box.
NB: You can close the spelling and grammar dialog box even if the process is not complete by choosing Close.
Using the thesaurus
This is an editing tool that helps the user find words or phrases with similar meaning (synonyms) or opposite meaning (antonyms) to the one selected.
To use the Thesaurus:
Autocomplete The auto complete feature displays a complete word when the user types the first few characters of the word. This enables the user to type faster by simply accepting the suggested word if indeed he/she intend to type it. To accept the suggestion, simply press the Enter key, and continue typing other word or phrases
The figure shows an auto text that automatically completes Dear sir or Madam text entries.
To turn auto complete on/off
Autocorrect
The auto correct feature automatically detects wrongly spelled or capitalised words and replaces them with the correct word. However, the settings of auto correct are user defined e.g. if a person keeps on typing the word certain as certain, set the auto correct feature to replace the later with the former. Figure 1.18 shows the auto correct feature.
To turn auto correct on/off
Undo and redo
Undo: It reverses the last command that was issued in Order to revert back to the previous state. To undo, click Edit then Undo command.
Redo: It does the last undone action. To redo, click Edit, then Redo Command.
Formatting a document
Formatting refers to applying various styles or features to enhance the document’s appearance. You can format text, a paragraph or a page.
Text formatting
Text formatting refers to features such as changing fonts (type, style and size of characters), changing text color, underlining, bolding Italicising etc. You can use either the formatting tools bar or the Format menu to underline, bold, etc.
To format existing text using the format menu
(a) Activate the font dialog box.
(b) Click the down arrow at the right of Underline style and select. The underline style required e.g. single, double, dashed etc.
(a) To italicise activate the font dialog box.
(b) Click Italic.
(a) Activate the font dialog box
(b) Click the down arrow at the right of font color list box and
Select the color of your choice.
Using formatting toolbar
As mentioned earlier, the formatting toolbar lets the user easily format text by clicking the required format button. To format some text, highlight it first then click a command on the toolbar.
For example to bold text, highlight it then click then bolding command (B) on the formatting toolbar.
Paragraph formatting
Text alignment
Text alignment refers to how text is lined up on the page relative to the left, right or center of the page. There are four ways in which text can be aligned namely left aligned, centered, right aligned and justified.
Left alignment
Lines of text are lined up evenly along the left margin but unevenly at The right margin. This is the default alignment. To align left,
Right alignment
This is opposite of left alignment. Lines of text are lined up evenly along the right margin but unevenly at the left margin. To align right,
Center alignment
The lines of text are centered unevenly between the left and right margins.
To center text,
Select centered from alignment list box, then click OK.
Justification
Lines of text are arranged evenly along the left and right margin.
To justify text,
Paragraph, select Justify from Alignment list box, then click OK.
Change case
When typing a text, there are a number of cases the user may intend to apply in order to create contrast within the text. These are:
Figure 1.21 shows a dialog box for change case.
To change case in an existing text;
Drop caps
There are times when you wish to attract the reader’s attention by making the first character in a sentence large, taking more space in the next line. Such kind of a character is said to be “dropped”.
To apply drop cap;
Indenting paragraphs
Indentation refers to moving the text away from the margin. You can indent the first sentence in a paragraph (first line), the whole paragraph (full indent) or the rest of the text except the first line (hanging indentations).
First line indent
In the by text box
Click OK to apply the indent and close the dialog box. The paragraph will be indented
NB: You can also indent the first line by positioning the cursor at the beginning of the paragraph then press the Tab key.
Hanging Indent
Full indent
Setting tabs
Tabs are used to indent the first line of a paragraph or create columnar data. By default the tab stop is set at 0.5 of an inch. To change the default setting:
Setting tabs using the ruler
The easiest way to set tabs is by using the ruler. On the left comer of the horizontal ruler is a tab alignment button that lets the user select the type of tab. Figure 1.28 shows various tab alignment buttons, while Table 1.1 gives an explanation of each button.
To set the tab using the ruler;
| Button | Name | Purpose |
| Left tab | Text is left aligned | |
| Center tab | Text is centered | |
| Bar tab | Inserts a vertical line at | |
| Tab stop and align text to | ||
| The right of the line | ||
| . | Decimal tab | Text is aligned at decimal |
| Character | ||
| Right tab | Text is right aligned |
Table 1.1 Examples of tabs
Line and character spacing
Line spacing refers to the vertical distance between lines of text. The default line spacing is single spacing. This type of spacing accommodates the characters in a text leaving a small extra space between lines. Character spacing on the other hand refers to the space between the characters in the text.
To change line spacing:
Bullets and numbering
Bullets and numbers are used to mark steps in a procedure or items in a list.
To apply bullets and numbers in a list:
(a) To apply bullets, click the Bulleted tab.
(b) To apply independent numbers click the Numbered tab.
(c) To apply outlined numbered list, click Outline Numbered. Tab
Section breaks
A break is used to identify where a section, a column or a page ends and the beginning of next. This allows the user to apply more than one paragraph or page format in the same document especially when it comes to page layout, size, different margins etc.
To insert a section break
Formatting pages
Inserting page breaks
A page break identifies the end of one page and the beginning of the next. NofQ1ally, Word automatically inserts a new page after the current. One is full. However, there may be a need to start a new page even if the. Current one is not full.
To insert page breaks:
Creating columns
To, create columns on existing text:
Page setup
Page setup options let the user specify the size of the margins, paper size, paper source and layout.
Setting margins
Margins are blank spaces around the edges of the page. Only text and objects inside the margins are printable.
To set up margins:
Setting the paper size
By default, the paper size may be either Letter or A4. An A4 paper has dimensions 210 mm x 297 mm
To specify a different paper size
Specifying page orientation
The term page orientation refers to the positioning of the page in relation to the text. The two available orientations are:
Portrait: text and graphics are printed with the longest side vertically upright. For example, on an A4 piece of paper, the 210 mm edges are at the bottom and top.
Landscape: With landscape, text and graphical objects are placed with the longest side of the page placed horizontally and the lines of text printed parallel. For example, to create a timetable on an A4 page, the 297 mm side should be horizontal.
To select the orientation:
Page layout
This option lets the user specify how text will be placed on the page from the margins. By default, text starts from the top margin.
To change the layout
Inserting headers and footers
Headers, footers and page numbers make it easy to locate information. Headers are few words placed at the top of every page while footers appear at the bottom. To insert headers and footers:
Inserting page numbers
To give your document page numbers:
Creating and editing tables
Creating tables
A table is a feature in Microsoft Word made up of rows and columns that is used to organise and enhance display of information.
Creating a new table
. .
You can create a table either by using the Insert Table command from tables menu, or by using Draw Table tool that resembles a pencil to create more complex tables.
To create a table using the insert table command;
NB: You can insert a table by clicking the table button on the standard toolbar, then drag to select the number of rows and columns.
To create a table using the drawing tool:
Formatting and editing a table
Inserting rows and columns
To insert a row:
To insert a column:
Adjusting the column width:
Deleting rows, column or cells
Merging cells in a table
This refers to combining more than one cell in a table. To merge cells:
Splitting cells in a table
This refers to subdividing a cell or cells into more cells. To split cells:
Formatting table borders and shading
Word provides the user with automatic formatting feature that lets you choose border styles and shading.
To format a table:
NB: You can also format a table by using the table’s toolbar. If the toolbar is not displayed, click view point to toolbars then click tables and Borders.
Table conversions
With convert feature in Microsoft Word, you can convert a table to lines of text and vice versa.
To convert a table to text
To convert text to table:
Importing tables
Microsoft Word lets you import tables from other applications or an existing file. To import a table,
Performing arithmetic calculations in a table
It is possible to perform mathematical calculations such as sum, product and count, if a table has numerical figures.
To perform calculations:
Sorting
In Microsoft Word you can sort a list of text, numbers and dates in ascending or descending order.
To sort a list or table:
Mail merge document
Mail merge is the process of generating personalised letters or documents by combining a main document, e.g. a letter, with an existing data source such as the address book. Therefore in mail merge, the three files created are:
To create the main document,
1 From the file menu, select New to create a new document. You can also open or retrieve an existing document.
3 Click create button, to select the type of document needed e.g. form .letters. Select the active window as the main document this means that the currently running document will be the form letter that will be later merged with a data source to produce individualised letters.
The next step is now to create a data source.
Open Data. Source To use existing addresses from an electronic address book, click on Use Address Book. To create a new list of names and addresses, first choose the necessary fields from the create data source box then save the record structure. A message appears asking you whether you want to edit the data source or the main document choose one then the Next.
Merging the document
Once you finish inserting merge fields from the data source in the main document, you are now ready to merge. There are several merge options:
To merge to a new document
Click the Merge to new document icon on the mail merge toolbar.
Merging to printer
Click the .Merge to printer, icon on the mail merge toolbar. Before you merge to a printer or other device, you may want to preview the appearance of the merged documents. For example, you can preview the merged documents one at a time. You can also collect the merged documents into a new document, so you can review and personalise the documents.
Preview merged documents
Before you print the documents, ensure that you’ve inserted merge fields in the main document and selected a data source. To preview, click anywhere in the main document, and then click View Merged Data on the Mail Merge toolbar.
Microsoft Word displays information from the first data record in place of the merge fields.
Send merged documents via e-mail or fax
Click the merge button on the Mail merge toolbar Select e-mail or fax in the merge to box. Click the Setup button to specify the e-mail addresses or faxing number then click the merge button. The internet connection wizard starts and if your computer is properly configured, the mail merged document will be sent.
Inserting graphics
Working with graphics
The term graphics refers to non-text images generated by a compute! This includes photographs, drawings and graphs. Graphics present information in a form that is easy to understand.
You can insert a graphical object from Microsoft Clip Gallery, a scanner or by using drawing tools available in Microsoft Word.
Inserting a clip art or a picture from clip gallery:
Fig. 1.42: A clip art image
Inserting an image from a scanner
The computer must be connected to a scanner to complete this procedure. A scanner is a data capture device that transforms a hand copy or real graphical object into digital form.
To scan an object:
Inserting a picture from another file
5 Then click the Insert button.
6 When the image appears on the screen you can edit and format it as required the same way you would with a clipart.
Editing and formatting pictures
To format or edit a picture:
Microsoft Word provides the user with a picture editing toolbar that lets you adjust the brightness, contrast, change it to black and white or grayscale and crop the image. Cropping refers to hiding the unwanted details so that they do not come out when printing.
To display the picture toolbar, click on View menu, point to toolbars then select Picture. The picture toolbar has buttons that enable a person to format a picture to format a picture, click it to select it then use the commands on the picture toolbar.
Drawing an object using MS Word drawing tools
Microsoft Word provides the user with basic drawing tools such as polygons, lines, a circle, stars and banners, call outs and many others. If the drawings toolbar is not displayed, click on View menu, toolbars then click on Drawing. The toolbar will be displayed which a button has labeled Auto shapes, an arrow, a line, square and a circle
To draw a line, a circle an arrow or a rectangle:
To draw an object using the Auto shapes:
Editing and formatting a drawn object
You can resize, move, fill color and change the drawing outline.
To resize or move a drawing.
To fill the object with color and fill effects:
1 Click the object. The place holders appear.
2 Click the down arrow of fill color button, the one that looks like a bucket pouring ink.
3 Select the color you want applied. To fill the drawing with texture, gradient or pattern, click the Effects button. From the resulting dialog box, select the appropriate fill effect.
Printing a document
Printing in Microsoft Word
Because the main purpose of any word processor is to prepare documents for printing, this cannot be accomplished without a printer. The choice of a printer depends on the quality of hardcopy desired. Before you print, it is very important that you preview you document to confirm that no details are outside the printable area and that the document layout is okay.
Using print preview
In Microsoft Word, to view your document before printing proceed as follows:
To print:
(c) Number of copies to print per page in the Number of copies box then,
SPREADSHEETS MS-EXCEL
Chapter outline
2.1 Definition of spreadsheet
2.2 Components of a spreadsheet
2.3 Application areas of a spreadsheet
2.4 Creating a worksheet/workbook using Microsoft Excel
2.5 Cell data types
2.8 Editing a worksheet
2.9 Worksheet formattin2.10 Data management
2.11 Charts/graphs
2.12 Printing worksheets
2.1 Definition of a spreadsheet
A spreadsheet is essentially a ledger sheet that lets you enter, edit and manipulate numeric data. There are two types of spreadsheets namely:
A manual spreadsheet is the most commonly used type by book keepers as a ledger book with many sheets of papers divided into rows and columns on which various amounts of money are entered manually using a pen or pencil. You can visit your bursar’s office and request to see a ledger sheet.
An electronic spreadsheet on the other hand is prepared using a computer program that enables the user to enter values in rows and columns similar to the ones of the manual spreadsheet and to manipulate them mathematically using formulae. ‘
In this book, the word spreadsheet shall be used to refer to the electronic spreadsheet. ‘.
Advantages of Using Electronic Spreadsheets over Manual Spreadsheet
Examples of spreadsheets
In this book, the spreadsheet that will be considered in details is Microsoft Excel.
Components of a spreadsheet
A spreadsheet has three components
Worksheet
This is the component in which data values are entered. It is made up of rows and columns. The intersection between a row and a column is called a cell. A row is a horizontal arrangement of cells while a column is a vertical arrangement of cells. Each row is labeled with a number while each column is labeled with a letter as shown in the Figure 2.1. Each cell is referenced using the column label followed by the row label e.g. cell B3 has the value 20. A group of many worksheets make up a workbook.
A B C D E F
| 1 | |||||||||||
| 2 | |||||||||||
| 3 | 20 | ||||||||||
| 4 | |||||||||||
| 5 | I |
Fig. 2.1: A Worksheet
Database
Data values can be entered in the cells of the spreadsheet and managed by special Excel features found on the Data menu. These features were incorporated in Excel but they actually belong to database management software. One of such feature is filtering records, using forms, calculating subtotals, data validation pivot tables and pivot chart reports.
If the data values for the same entity (related values) are entered on the same row, they form a record. Hence a worksheet can be manipulated to some extent as a database that has data records entered in it. Figure 2.2 shows a worksheet having two records, Joy and Jeff.
A B c D EF1
| 1 | Name | IDNo. | Age | Nationality | |||
| 2 | Joy | 123445 | 25 | Kenyan | |||
| 3 | Jeff | 125675 | 35 | Ugandan | |||
| 4 |
Fig. 2.2: A spreadsheet with records
NB: A spreadsheet file is structured in such a way that it can be visualised as a table of records. That is why such a ‘file can be imported into a database program as will be discusses later in databases.
Graphs
A graph is a pictorial representation of the base data on a worksheet. Most spreadsheets refer to graphs as charts. A chart enables the user to present complex data elements from a worksheet in a simple easy to understand format. Examples of charts are pie charts, line charts and bar charts. As shall be discussed later, it is easy to generate charts when working with a spreadsheet program. Figure 2.3 shows an example of a pie chart.
2.3 Application areas of a spreadsheet
Statistical analysis
Spreadsheets provide a set of data analysis tools that can be used to save steps when developing complex statistical or engineering analyses. The user is usually expected to provide the appropriate data and parameters for each analysis. The statistical tool then uses appropriate automated statistical or engineering functions and then displays results in an output table. Some of the tools generate charts in addition to the output tables.
Because most of these tools are complex, the user needs to have the statistical background knowledge before attempting to use the tools. Examples of some simple statistical functions include the following:
For example a set of values may be composed of:
10 20 30 40 50 60.
The average of the set is 35 and its median is also 35. The median is found by taking the average of the two numbers at the centre of the set, in this case 30 and 40.
Accounting
Many accountants find the spreadsheet a useful tool to use in recording daily transactions and keeping of financial records. Spreadsheets provide a user friendly environment for financial management and they come with inbuilt functions that make accounting tasks easier. For example, the spreadsheet can be used by accountants to do the following:
Other formula like sum, average, product etc. enables the accountant to carry out his daily work without any problem.
Data management
A spreadsheet enables neat arrangement of data into tabular structure. Related data can be typed on the same worksheet. However, when data is on different worksheets, the worksheets can be linked to enhance accessibility.
Data management functions include sorting, filtering (displaying only the required items) and using forms to enter and view records.
Spreadsheets enable the user to create, edit, save, retrieve and print worksheet data and records.
Forecasting (“What if” analysis)
The automatic recalculation feature enables the use of “What if’ analysis technique. This involves changing the value of one of the arguments in a formula to see the difference the change would make on the result of the calculation. For example, a formula to calculate a company’s profit, margin may be as follows:
Profit =, (Total units sold x sale price) – (Total units bought x cost price) – Operating ‘expenses.
A sales manager in the company c n ask the following question: What if sales increase by 20%, how much profit wills the company make? The manager substitutes the total units sold value with one that is 20% higher and the spreadsheet automatically displays the new profit. A traditional analysis method would require a different work sheet to be prepared. Therefore, this method can be used for financial forecasting, budgeting, stock portfolio analysis, cost analysis, cash flow etc.
Creating a worksheet/workbook using Microsoft Excel
To start Microsoft Excel, click Start button, point to Programs and then select Microsoft Excel from the programs menu This procedure may vary slightly depending on the version of Excel you are using or the computer’s hardware and software configuration.
The Windows environment allows a person to place shortcuts to a program’s executable (.exe) file in various places like the desktop. If the Excel shortcut is on the desktop, simply double click it to start the application.
The Microsoft Excel application window opens as shown in the Figure 2.5. Make sure that you can be able to identify all the labeled parts of the Microsoft Excel application window.
The Microsoft Excel application window
The Microsoft Excel application window is made up of the following components:
Title bar: It has the title of the application and control buttons for minimising, maximising and closing the application
The menu bar: It displays a list of menu options e.g. File, Edit, View etc. Clicking one of them displays a menu that has commands which can be selected in order to manipulate data in the spreadsheet. ‘
Tool bars: The most common of these are the standard and formatting toolbars. The most important thing is to be able to identify each toolbar by its icons. The standard toolbar has shortcuts to some of the most commonly used menu commands like print, copy, paste and save. The formatting toolbar has shortcuts to the commonly used commands found on the format menu option
Formula bar: This is one of the most important components of the Microsoft Excel application window. It enables the user to enter or edit a formula or data in a cell. You can identify the formula bar because it has an equal sign (or fx). The name box to the left of the formula bar displays the position of the cell in which data or a formula is being entered which is also called the current cell. If the formula bar is not available, click on View menu then select Formula bars. A check mark appears on the left of the selected item to show that it is now displayed on the screen.
Cell pointer: It marks the position of the current cell or the insertion point. It is special cursors that is rectangular in shape and makes the current cell appear as if it has darker boundaries.
The Worksheet: Consists of cells, rows and columns. Data is entered here for manipulation.
Status bar: It shows the processing state of the application. For example, on its left is the word Ready which shows that the spreadsheet is ready to receive user commands. ‘
Worksheet labels: These are usually of the format Sheet 1, Sheet 2 etc. A workbook may have several sheets. It is also possible to rename the sheets by right clicking on the labels then choosing rename command from the shortcut menu that appears. The active sheet (one being used) has its label appearing lighter in colour than the rest. To move to a particular sheet in the workbook, simply click its sheet label.
Vertical and horizontal scroll bars: Clicking the arrows at their ends moves the worksheet vertically and horizontally on the screen respectively.
Worksheet layout
The worksheet has the following components: Cells: An intersection between a row and a column.
Rows: Horizontal arrangement of cells. Columns: Vertical arrangement of cells.
Range: Is a group of rectangular cells that can be selected and manipulated as a block.
Navigating the Microsoft Excel screen
Creating a worksheet
At its simplest level, creating a worksheet consists of starting the spreadsheet program and entering data in the cells of the current worksheet. , However, a person can decide to create a worksheet either using the general format or from a specially preformatted spreadsheet document called a template.
Using the general format
When a spreadsheet program is running it will present the user with a new blank screen of rows and columns. The user can enter data in this worksheet and save it as a newly created worksheet. If this is not available then click File menu option and select the new command. The dialog box shown in Figure 2.8 will be displayed on the screen. On the General tab, double click the workbook icon. Enter data in the new worksheet created.
Using a template
Click File menu option then new command. On the spreadsheets solutions tab, double click the template that you wish to create. Figure 2.9 below shows some examples of templates that may be present for selection.
NB: If the template was saved previously on the hard disk, it will open as a new worksheet with all the preformatted features present allowing the user to enter some data. However, some templates may require the original program installation disk in order to be able to use them because they may not have been copied to the hard disk during program installation.
Editing a cell entry
Editing a cell means changing the contents of the cell. Before the contents in a cell can be. Changed, the cell must be selected by making it the current cell.
To edit a cell entry proceeds as follows:
.1. Move the cell pointer to the cell you wish to edit.
Selecting a range
As you have experienced with the previous two examples, working with one item at a time is tedious and time consuming. Using a range saves time when working with a large .amount of data.
A range is a rectangular arrangement of cells specified by the address of its top left and bottom right cells, ‘separated by a colon (:) ego Range AI:CIO is as shown in Figure 2.10.
Selecting multiple ranges
When using a mouse, you can select more than one range without removing the highlight from the previous. To do this:
Hold down the Shift key or the Ctrl key while you click on the row header of the second range you want to highlight. What happens? Do you notice the difference when holding down the shift and the ctrl keys?
Hiding rows/columns
You can hide some rows or columns in order to see some details, which do not fit, on the screen. To do this:
Saving a worksheet
To save a worksheet, one has to save the workbook in which it belongs with a unique name on a storage device like a hard disk. The procedure below can be used to save a workbook:
Retrieving a saved workbook
This means opening a workbook that was previously saved.
Closing a worksheet
Click File then Close command. This closes the worksheet but does not
Close the Excel spreadsheet program. Alternatively, click the; close button of the worksheet window
Exiting from the spreadsheet
Click File then Exit command. This closes not only the worksheet but also the spreadsheet program as well. Alternatively click the close button of the main application window.
Cell data types
There are four basic types of data used with spreadsheets:
Labels
Any text or alphanumeric characters entered in a cell are viewed as labels by the spreadsheet program. Labels are used as row or column headings usually to describe the contents of the row or column. For example, if a column will have names of people, the column header can be NAMES. Sometimes, numbers can be formatted so that they can be used as labels. To achieve this add an apostrophe just before the most significant digit in the number. For example, the number 1990 will be treated as numeric. if typed in a cell but’ 1990 will be treated as a label.
Labels are aligned to the left of the cell and cannot be manipulated mathematically.
Values
. ,
These are numbers that can be manipulated mathematically. They may include currency, date, numbers (0-9), special symbols or text that can be manipulated mathematically by the spreadsheet.
Formulae
These are user designed mathematical expressions that create a relationship between cells and return a value in a chosen cell. In Microsoft Excel, a formula must start with an equal sign. For example, the formula
=B3+D4 adds the contents ofB3 and D4 and returns the sum value in the current cell.
Excel formulae use cell addresses and the arithmetical operators like plus (+) for addition, minus (-) for subtraction, asterisk (*) for multiplication and forward slash (I) for division.
Using cell addresses, also called referencing, enables Microsoft Excel to keep calculations accurate and automatically recalculates results of a formula in case the value in a referenced cell is changed. This is called automatic recalculation.
Functions
These are inbuilt predefined formulae that the user can quickly use instead of having to create a new one each time a calculation has to be carried out Microsoft Excel has many of these formulae that cover the most common types of calculations performed by spreadsheets. To add the contents of cell B3 and D4 the sum function can be used as shown below:
= Sum (B3:D4)
2.6
Cell referencing
A cell reference identifies a cell or a range of cells on the worksheet and shows Microsoft Excel where to look for the values or data needed to use in a formula. With references, you can use data contained in different cells of a worksheet in one formula or use the value from one cell in several different formulae.
By default, Microsoft Excel uses the A 1 cell referencing style. This means that a cell is identified by its column label followed by the row number. However, the Rl Cl referencing style can be used. In this case, the cell is referencing by its row number followed by its column number. The table below gives a few examples of equivalent referencing using both styles.
| A1 style | R1C1 style |
| B2 | R2C2 |
| C10 | R10C3 |
| E20 | R20C5 |
The RlCl style is useful when automating commonly repeated tasks using special recording programs called Macros.
Relative referencing
When performing tasks that require cell referencing, you can use formulae whose cell references keep on changing automatically depending on their position in the worksheet. This is called relative cell referencing. A good example would be if you type the formula =Al+Bl in cell Cl. If the same formula is copied to cell C2 the formula automatically changes to =A2+B2.
Absolute referencing
These are cell references that always refer to cells in a specific location
, of the worksheet even if they are copied from one cell to another. To make a formula absolute, add a dollar sign before the letter and/or number,
such as $B$lO. In this case, both the column and row references are absolute. .
Referencing using labels and names
Labels of columns and rows on a worksheet can be used to refer to the cells that fall within those columns and rows. It is possible to create a name that describes the cell or range then use it instead of having to specify a range with actual cell references. Such a descriptive name in a formula can make it readable and easier to understand its purpose. For example, the formula =SUM(SecondQuarterProfits) might be easier to identify than =SUM(AlO:C20). In this example, the name SecondQuarterProfits represents the rangeAlO:C20 on the worksheet. Names can also be used to represent formulae or values that do not change (constants). For example, you can use the name .Tariffs to represent the import tax amount (such as 7.0 percent) applied to imports.
To create a named range
To create a named range proceeds as follows: 1. Select the range to be named:
2.7 Basic functions and formulae
Formulae perform mathematical operations ranging from very simple arithmetic problems t9 complex scientific, financial and mathematical analysis.
Statistical functions.
=Average(D lO:E 1 0) returns 25 as the average of the two values.
= count (AIO: EIO) many return a value 5 if all the cells have values.
Logical functions
Mathematical functions
Arithmetic formulae – using operators
Operator Function
+ (plus) adds values as specified
– (minus) . subtracts values as specified
* (multiplication) multiplies values
/ (division) divides values.
( ) parenthesis encloses arguments to be calculated first.
For a formula =(Al +C3)/E20, if the value in E20 is not zero, the result is displayed in the current cell.
Order of execution
If several. Operators are used in a single formula; Microsoft Excel performs the operations in the order shown in Table 2.3. Formulas with operators that have same precedence i.e. if a formula contains both a multiplication and division operator are evaluated from left to right. Enclosing part of the formula to be calculated in parentheses or brackets makes that part to be calculated first.
| Operator | Name | Precedence | |
| 1. – | Negation as in -1 | 1 | |
| 2.% | Percent | 2 | |
| 2. 1\ | Exponentiation | 3 | |
| 3. * and / | ! | Multiplication and division | 4 |
| 4. + and – | Addition and subtraction | 5 | |
| 6. =,<>,>,<,<=,>= | Relational | 6 | |
Table 2.3: Operators’ order of execution
2.8
Editing a worksheet
Coping and moving data
Spreadsheet software automates many processes that could have been tedious if done manually. For example with Microsoft Excel, you can do calculations using formulae fairly easily as you give the data and correct instructions to the program. Copying and moving of, data can also be done quickly and efficiently.
When data is cut or copied from the worksheet, it is temporarily held in a storage location called the clipboard.
Copying data
To copy a cell or a range of cells:
Moving data
Unlike the Copy command where a duplicate copy is created, the Move command transfers the contents of the original cell (s) to a new location.
To move a range of cells:
2.9 Worksheet formatting
Worksheet formatting refers to enhancing the appearance of the worksheet to make it more attractive and appealing to the reader. Appropriate formatting should be used to lay emphasis, catch attention and bring otherwise II hidden detail to the fore of the document.
The golden rule of formatting is to use simple clear formats. It essentially consists of changing text colour and typeface (font), size, style and alignment. In Microsoft Excel, format the cells whether empty or not and their contents will acquire the set format automatically.
To format a single cell, make it the current cell then format menu option and select the cells command In the format cells dialog box, make the formatting specifications that you wish then click the ok button to apply. If it is a range of cells, they must be highlighted first before formatting them as a block of cells.
Formatting text
NB: Alternatively, use the formatting toolbar to accomplish all your text formatting needs. Notice that the options in the font dialog box are commands on the formatting toolbar.
Formatting numbers
Number Meaning
General general format cells have no specific number format.
Number Used for general display of numbers e.g. 2345.23.
Currency For displaying general monetary values e.g. $100, Ksh.10.
Accounting Lines up the currency symbols and decimal poin s. Displays date in chosen format.
Date Displays time in chosen format.
Percentage Multiplies the value in a cell with 100 and display ‘ it as %.
Text Formats cells to be treated as text even when numbers are entered.
Custom For a number format not predefined in Microsoft Excel, select custom then define the pattern.
Worksheet borders
You may need to put a printable border around your worksheet or in a range of cells to make it more attractive and appealing. To put a border:
Formatting rows and columns
Sometimes, the information entered in the spreadsheet may not fit neatly in the cell set with the default height and width. It therefore becomes necessary to adjust the height of a row or the width of a column. The standard width of a column in Microsoft Excel is 8.43 characters but can be adjusted to any value between 0 and 255.
Changing column width
NB: Alternatively, move the cell pointer to one of the cells of the column then click Format, point to Column then click Width command from the sidekick menu. Type a width in the dialog box that resembles Figure 2.17 then click Ok.button to apply.
NB: To change the widths of several columns at the same time, highlight them first before following this method.
Changing row height
NB: Alternatively, click Format point to Row then click Height from the sidekick menu that appears. Type the height that you wish in the dialog box that appears and then click OK button to apply.
Inserting rows and columns
I, Click cell A5 to make it the current or active cell.
2.clik insert then columns to insert a ‘row above cell A5 and shift all the other rows downward.
OR
Click insert then Columns to insert a column to the left of column A and shift all the others to the right.
NB: Alternatively, click insert then cells to display the dialog box select the entire row or entire column options to insert a row or column respectively.
Global worksheet formatting
The word global in this case refers to the entire worksheet. In order to format the whole worksheet globally, it must be selected as a whole.
Two methods can be used to select a worksheet globally:
OR
Notice that the whole worksheet becomes highlighted. It can now be formatted as one big block using format cells command.
Using autoformat
It allows the user to apply one of sixteen sets of formatting to & selected range on the worksheet. This quickly creates tables that are easy to read and are attractive to the eye..
2.9 Data management
At times, it becomes necessary to use advanced data management tools to manage large ,data stored on a ‘worksheet. For example, if the worksheet has many records, it may become necessary to arrange them in a particular order using a method called sorting for easier access to data items. Other methods of data management include use of filters, total/subtotal function and forms.
Sorting
To carryout sorting proceed as follows:
Filtering data
Filtering is a quick and efficient method of finding and working with a subset of data in a list. A filtered list will only display the rows that meet the condition or criteria you specify. Microsoft Excel has two commands for filtering lists.
In this Pupil’s Book we will look at the autofilter.
Autofilter
Filters can be applied to only one list on a worksheet at a time.
NB: Sometimes while looking through a list of values on a large worksheet, you may come to a value of interest and want to see all other occurrences of the value in the spreadsheet. Simply click the cell that has the value then click auto filter on the standard toolbar. Microsoft Excel turns on AutoFilter and then filters- the list to show only the rows you want.
Subtotals function
Consider the following scenario: A company that has many salespersons
will need to know how much each of them should be paid at the end of a period by looking at individual sales volumes. Also, the grand total for all the payments has to be calculated. Therefore, if the salespersons are held in a list, there would be need to calculate the amount due to each of them. This can be called a subtotal in the list. All the subtotals can then be added together to make the grand total. Consider the following list:
Name Amount Owed
Stephen ` 6000
Joy 3000
Stephen 2000
Virginia 5000
Joy 800
Stephen 200
Virginia 5000
Microsoft Excel can automatically summarise the data by calculating subtotal and grand total values of the list. To use automatic subtotals, the list must have labelled columns and must be sorted on the columns for which you want subtotals. In this example, the list is first sorted by name
Totals function
Use theAutoCalculate feature in Microsoft Excel to automatically show the total of a selected range. When cells are selected, Microsoft Excel displays the sum of the range on the status bar. Right clicking this function displays other functions like Min, Max and Average that can also be used. To find the total of a range, highlight it then click the autosum icon ∑ on the standard toolbar.
Forms
A form is a specially prepared template that the users can use to enter data in a worksheet. It is specifically formatted to enable users to enter data in a format that is more convenient to them. If data is collected on paper before entering in the computer, then a form can be created to have the layout of the data on the paper to quicken data entry procedures. To display a form: Click ‘Data, then form.
2.10 Charts/graphs
Charts/graphs are graphics or pictures that represent values and their relationships. A chart helps the reader to quickly see trends in data and to be able to compare and contrast aspects of data that would otherwise have remained obscure. Microsoft Excel has both two-dimensional and 3-dimensional charts that can be used instead of the raw data in the table that has to- be studied for a long time to understand it.
The various types of charts available include column, bar, line. Pie, bubble and area charts among others. Consider carefully the type of chart that would best represent the base data in the worksheet before creating one. For example, if the aim is to depict the performance index of a student from Form I-to 3, a line chart would be most appropriate because it clearly shows the trend in performance.
Types of charts
To view types of charts, right click the chart object then select the chart type command.
Creating a chart
A chart must be based on values that are already entered in the worksheet.
To create a chart:
This will shrink the dialog box so that only the category labels text box is shown. Highlight the data labels from the worksheet.
Moving and resizing a chart
Once the chart is created, its size and location can be changed in the worksheet. The chart element is enclosed inside a boundary called the chart area and hence both can be resized independently. Simply click the object you wish to resize and use the object handles just like in objects to drag to size. To move the chart, click inside the chart area then drag to the desired position.
Data ranges
A data range is a rectangular block of cells that provides the base data that is used to create the chart. In charting, a data range is referenced as an absolute range e.g. .
=Sheetl !$B$2:$C$8 which means that the base data is found on Worksheet 1 and absolute range B2:C8.
To see the data range of a chart, right click it then select the Source data command. .
Labels
Each representation of data on a chart can either be labelled by a value
or text label. For example, in a bar chart that compares the height of pupils, each bar can be given a value label to make it more readable.
To label:
the shortcut menu.
Headings and titles
Each chart must have a heading showing clearly what it represents. To I make the chart understandable, include axis titles.
. To include axis titles proceed as follows:
Legends
The legend is like a key that explains what each colour or pattern of the data representation in the chart means. For example, Microsoft Excel may give red colour to one data value and green to the other. Without a legend it would be difficult to know how to differentiate the two sets of values.
: To create a legend:
.1.Right click the chart then select the Chart options command.
2.11
Printing worksheets
A worksheet will finally be printed for sharing with others or for filing purposes. If it contains objects like charts, it may not fit on a standard printing page using the default printing options and settings. Therefore, Microsoft Excel allows the user to preview and set up the pages of a’ worksheet in order to fit them on the hard copy page.
Page setup
Print preview
It displays the worksheet from the point of view of the printer i.e. exactly the way it will look when printed. Before using this command, make I sure the chart is deselected.
I Print options
To print click File then Print command. The print dialog, box appears as shown in Figure 2.29 .
(a) Selection – this prints the selected worksheet area.
(b) Workbook – prints all the worksheets in the workbook.
(c) Selected chart – prints the selected chart only.
Page orientation
As explained earlier, page orientation refers to the layout of the text on the page. A worksheet can also be printed on either landscape or portrait depending on the number of columns across the worksheet.
Pages and copies .
The number of copies box specifies how many copies of a particular worksheet or workbook should be printed.
Sometimes only some specified pages in a workbook are specified for printing e.g. if a workbook has 100 pages and you wish to print only pages 50 to 60 select the page(s) range button then type 50 and 60 in the from, to boxes respectively before clicking the OK button.
Printing
After selecting all the options, click the OK button to print.
Some common printing problems
Possible problems and solutions
(a) The printer could be off. Switch it on and it will start printing.
(b) The data cable to the printer could be loose. Make sure it is firm at the ports.
(c) The wrong printer could have been selected. Select the right one in the print dialog box and send the print job again.
(d) A message appears on the screen reading that there is paper jam. I
The printer is clogged with a paper jam. Alert the lab, technician or the Teacher to clear the paper jam.
DATABASES
Chapter outline
3.1 Introduction to databases
3.2 Database concepts
3.3 Data organization in a database
3.4 Creating a database using Microsoft Access
3.5 Editing a database
3.6 Form design
3.8 Creating reports
3.9 Creating labels
Introduction to databases
We are often faced with the need to keep, search for or give a report of daily experiences. This is the reason why many people use data storage methods like recording daily experiences in a diary. Traditionally, human beings used to manage data and information manually by using simple devices. However these methods have a number of weaknesses which include
Today, computerized systems have radically changec4the way data and information is managed by use of special programs called Database Management System (DBMS).
A database is a collection of structured and related data items organised so as to provide a consistent and controlled access to the items.
Database concepts .
Computerised database creation and manipulation is achieved using Database Management System software. This software facilitates the creation, organisation and maintenance of databases. Examples of database management software’s include Microsoft Access (Ms Access), Oracle, FoxPro, Dbase/V, Lotus Approach etc.
The functions of database management software are to:
Database models
Databases are classified according to the method used to organise data. The main database models are;
NB: Current database models are called object relational and object databases. However these models will not be discussed in details in this book.
Flat files
In a flat file model, a database holds only one set of data and is not any different from the manual files. For example, the teacher’s assessment report may consist of performance cards for every student in a class. Another example of a flat file database are the cards used in a library books catalogue. The cards are arranged sequentially for easy access e.g. alphabetically using books’ titles or by authors’ names. Figure 3.1 below is a sample record of a flat file.
| Name | Serah Seki |
| Admission number | 649 |
| Total marks | 680 |
| Number of subjects | 10 |
| Average | 68 |
| Position | 4 |
Fig. 3.1: Sample record in a flat file
Hierarchical model
In this model, data items are arranged in hierarchical (tree) form as shown in Figure 3.2. To access level two data items, you have to first access level 1 data items. Level 1 item is called the root component. A specific single path leads to each item at lower levels. Hierarchical model is rarely used in modem database systems.
Level 1 main data item
Path
Level 2 data item
Fig. 3.2: Hierarchical database model
Network model
In this type of organisation, links are used to express the relationship between different data items, forming a network of items as shown in Figure 3.3. Access to one item can be through multiple paths and from any item. This model is also rarely used in modem database systems.
Fig 3.3: Network database model
Relational model
This is the most common type of model used on minicomputers and microcomputers. In this type of organisation, related data items are stored together in structures called relations or tables. Relationship can be created between tables such that a record or records from one table relates to another or other records in another table. Tables 3.1 and 3.2 show customers and orders tables that are related by two fields; the customer number in Table 3.1 and customer ID in Table 3.2. In this case, the orders table shows that one customer with number 450 (Bat Hori) has made several orders.
| Customer Number | Name | Telephone number | ||||||
| 900 | Mary Koech | 02078907 | ||||||
| 230 | Peter Karimi | 0667896 | ||||||
| 450 | Bat Hori | 04456000 | ||||||
| Table 3.1: Customer number | ||||||||
| Customer ID | Order Number | Date | Amount (sh) | |||||
| 900 | 2380 | 2/3/2004 | 90 000 | |||||
| 450 | 811 | 2/5/2004 | 5000 | |||||
| ‘- | 450 | 234 | . 3/5/2004 | 13 000 | ||||
| 450 | 567 | 3/6/2004 | 13 000 | |||||
Table 3.2: Customer ID
Object oriented models . !
The next generation of database model will look at records as objects that are independent and relate with the other objects in the database. This concept is a bit difficult to conceptualise because such databases are still at developmental stage. However, many databases today combine object and relational concepts to come up with object relation models.
Features of a database management software
Most database software contains a collection of features that provides the user with a means to manipulate data in a database. These features include Tables/files, Queries, Reports generators, Form interface and a computer programming language within it. Microsoft Access database software that will be considered in this book has two distinct features used to automate operations namely Macros and Modules.
Tables/ file structure
This is a database structure that is used to hold related records. Tables are organised in rows and columns with each row representing a record while each column represents common fields in each record. Table 3.3 shows a table of six records and each record is made up of four fields.
| FIRST NAME | MIDDLE NAME | LAST NAME | ADDRESS |
| MBUGUA | STEPHEN | KIMANI | 250 KERUGOYA |
| ADERA | NELSON | ODUOR | 396 HOMA BAY |
| MARGARET | JUDY | WEKESA . | 761 NAIROBI |
| GATO | PATRICIA | MUILA | 170 TALA |
| MWELU | LUCY. | MWENI | 390 KANGUNDO . |
| KOECH | PETER | KORIR | 605 KERICHO |
Table 3.3: Table of six records and four fields
Queries and query language
A query is a database tool used to search for or question a database on specific records. Because a query is a question posed to the database, it returns a result for the user. In Microsoft Access, this result is called a dynaset. For example, assume you work with the National Irrigation Board (NIB), you may wish to display all those farmers from Mwea Rice Irrigation Scheme who delivered rice in January to the National Irrigation Board. You can use a query object or statements to get the required records.
The query statements are written using a special language called
Structured Query Language (SQL). The user creates a, query by writing Structure query language statements such as:
Select
Farmer Number, Name, Month of Delivery
From
Delivery Table
Where
Month of Delivery = “January”
Forms/screen input
A form is a graphical interface that resembles the ordinary paper forms used to collect data. However, a database form enables the user to view and enter data into a table. Figure 3.4 shows a sample form used for entering a student’s marks scored in four subjects and. the date of admission. Form interface is a more convenient and easy way of entering and viewing records from a table.
Reports
Most database systems provide the user with a tool for generating reports from an underlying table or query. It is the report generator that provides the user with a means to specify the output layout and what is to be output or printed on a report. Table 3.4 shows a sample report for employees’ salaries.
Net Pay Report
fay rol/no .Last.Name First Name. . .Basic salary PAYE Net salary.
07 Wangui Grace sh 80,000.00 Kshs 7,300.00 sh 72,700.00
09 Ochieng Mbenga sh 37,000.00 Kshs 3,800.00 sh 33,200.00
13 Mumbua Peter sh 22,000.00 Kshs 2,300.00 sh 19,700.00
20 Mbuvai Sicily sh 60,000.00 Kshs 5,700.00 sh 54,300.00
Table 3.4: Sample report
Macros
Some database software provides the user with a tool called a macro, that can be used to automate frequently performed procedures or tasks. For example, if you frequently use a particular form when you start a database program, you need to create a macro that automates the opening of the form.
Programming module
When your database becomes more and more complex, you may need a more powerful tool than the macros to automate your database operations further. Some database software come with their own computer languages associated with them. For example Microsoft Access comes with a language called Visual Basic included as a Module in the software. Using this feature, you can create a program that will print a query result over and over again until a certain condition is true. This can be illustrated using a simple statement like;
Print Student Report until NumberofStudents = 40 (Not a real command anyway).
NB: For the purpose of this book, only tables, forms, queries and reports, have been covered.
Data organisation in a database
One of the functions of a database system is to organise data for easy access, retrieval and manipulation. Data is organised from the simplest fQfll1 called a field to a very complex structure called a data,base.
Fields
A field is a character or a logical combination of characters that represent data item. For example, in a class list, the student name is a field.
Records
This is a collection of related fields that represent a single entity. An example of a record is the student report card that may contain the. student’s name, admission number, class, total marks, average and grade.
Files/tables
A file is a collection of related records. For example, the students’ file in a school database contains the details of all the students in the school.
Database
This is the highest in data organisation hierarchy that holds all related files ‘or tables. For example, a school database may contain students and staff tables/files.
Creating a database using Microsoft Access
Microsoft Access (Ms Access) is a package in Microsoft Office suite used for creating and manipulating databases. Because there are different versions of Ms Access such as Ms Access 95/97/2000 and XP, a general approach for carrying out tasks has been adopted in this book. However most of the illustrations are based on Access 2000 in order to maintain consistency.
Starting Microsoft Access
Microsoft Access screen layout
Like the other applications discussed earlier, Ms Access application Window has a title bar, menu bar, toolbars and status bar. However instead of having a work area like that ofMs Word or Excel, it provides the user with an object window from which you choose the type of an objectto work with such as tables, forms, reports e,tc. See Figure 3.7.
.Exiting from Microsoft Access
Because Microsoft Access consumes a large amount of computer memory it is advisable to exit from the application at end of each working session.
To exit:
From the File menu, click exit the close button on the title bar.
Guideline on designing a good databases
To design a good database which will require little time to maintain, consider the following:
Creating a table/file structure
To define a table structure:
Description of field data types
The type of data to be used in a database must be clearly defined for the purpose of manipulation and storage. For example, if a field is to be used for calculation, it must be defined as a number. The data types allowed in Ms Access include:
Text
This type includes alphabetic letters, numbers, spaces and punctuation. Use this data type for fields that do not need to be used for calculations such as names, places, identification numbers etc. This type of field accommodates a maximum of 255 characters.
Number
These are fields made up of numeric numbers 0 to 9 that are to be manipulated mathematically.
Memo
This is a field made up of alphanumeric (both alphabetic and numeric) data. Instead of using Text use this data type if you need to enter several paragraphs of text because it accommodates a maximum of 32 000 characters.
Date/Time
Used to identify a field as either a date or time. This is because date/time values can be manipulated mathematically in a database. For example, you can calculate the age of a person from the date of birth to the current data.
Currency
Used to identify numeric values that have decimals or fractions. Use this data type especially when dealing with monetary values such as fees balance, amount sold etc.
AutoNumber
This is a numeric value used if you wish Ms Access to automatically increment the values in a field. For example when entering a list of forty students and you have a field labelled StudNumber, the numbers will increase by one every time you enter a new record.
Yes/No
This is a logical field where an entry is either a yes or a no, true or a
false. For example a field may require you to answer whether you are a male or a female.
OLE Object
OLE stands for Object linking and Embedding. This type of field is mostly used with graphical user interface applications for inserting graphical objects such as pictures, drawings charts etc. – – –
Field properties
As you create more and more complex tables, you will find a need to use the field properties to specify finer details related to fields and the table entries expected. The field properties depend on the type of-the field selected. For example when you click on a Text field then the General tab you will see properties associated to text data type as shown in Figure 3.9. The various properties are:
Field size
This allows the user set the number of characters in a field instead of the default 50 for text fields for numeric field’s integer and long integer, Byte, Single and Double.
Integer and longer integer: Accept numbers with no decimals.
Byte: Can only accept a number from 0-255.
Single and double: Accept numbers with decimals. Single accommodates up to 38 decimal places while double, accommodates up to 308.
Format
Determines how information appears on the screen and when printed. For example, you can format a number to scientific, currency, percentage or general format.
Decimal places
For number and currency fields you can specify the number of decimal places.
Input mask ,
Input mask automatically formats the field entry into a specified format. F or example, if you enter a number such as 02000 I 00409874 and the input mask is set as 000-(00000)-000000, it is automatically displayed as 020-(00100)-409874. This property is mostly used to format phone and address entries.
Caption
This is a more descriptive name for a field to be used in a table or a form display. For example the caption for StuName could be Student Name.
Default value ,
This is a value that will appear automatically in the datasheet or form if ‘ nothing is entered by the user to change it. For example = Date -( ) automatically displays the current date in a date field.
Validation Rule
Logical expression restricts the values to be entered in a field. ‘For example, if you want to restrict marks entered in a field to values between
, zero and a hundred, type >=0 And <= 100.
Validation Text
The message that appears once the validation rule is violated. For example, you may create a validation text for the above validation rule I to display “Enter a number between 0 and 100” whenever the user enters I a value outside this range.
Required
Determines if an entry must be made in the field before you proceed to the next field or record. For example, if a primary key is required, you must enter before you proceed.
Allow Zero Length
This allows the user to proceed without making any entry in the field set as Zero length.
Indexed
An Index, facilitates the organisation of records for easy search. A primary key is an example of an index set to No duplicates to control double entry of a record (redundancy).
Primary key and Indexes
An index is a database feature used to speed up search and sort operations in a table. A key field also referred to as a primary key is a special index that enforces uniqueness in a table so that one record is not entered twice.
Ms Access uses the primary key to search for data stored in a table as well as define relationships between tables. Once a field is set as primary key, its datasheet is automatically indexed or sorted using the primary key.
To set a primary key:
To see another field as an index other than the primary key: 1. Open the table in design view.
6 In the Sort Order column, select either ascending or descending.
Entering data into a table
To enter/append data into a table:
Editing a database
Modifying the Datasheet view
To adjust the column size:
To adjust row height
To reorder fields:
Modifying the table structure
Once you create a table, you may need to add more fields, remove some fields, reorder the fields or change fields data types and properties. Before you modify the table it is important to save a copy to avoid losing everything in case you make a mistake
To make a copy of your table:
To modify the original table:
NB: If a table contains data and you make changes to the field data type, Ms Access may refuse to implement the changes. To avoid this problem, exit without saving and delete all the records from the table then return to the design view. You can then import a copy or copies of tables you backed up.
To import a table from another database:
import data from then click the Import button. Objects dialog box is displayed as shown in Figure 3.12.
Form design
Tables display many records at once from the database and in some cases you may not be able to see some fields properly. A form is an interface that enables the user to view and make data entries into an underlying table more easily. Figure 3.13 shows a sample form used to enter records into a books table.
In Microsoft Access, a form is designed using graphical objects called controls. A control is an object such as a text box, check box, command button or shapes that you place on a form design grid to display data or perform actions. There are two types of controls you can place on the grid: bound and unbound controls. A bound control is one whose source of data is a field in a table or query while unbound control is a control that is not connected to any data source.
You design or modify a form layout by dragging these controls to the required position. Figure 3.14 shows a form layout grid for a table called exam entry.
Creating a form layout using form wizard
To create a form layout, you can either use the form wizard or start from scratch. Using the form wizard you can create either a columnar, a tabular a datasheet or a justified form layout.
Columnar form: The fields for each record are displayed down a column i.e. each value displays on a separate line with field labels to the left. Tabular: Records are displayed from left to right across the page and labels appear at the top of each column and each row represents a new record.
Datasheet: The form resembles a table datasheet view.
Justified: One record occupies the whole form.
To create a form using the form wizard:
Creating a form using autoform wizard
You can easily create a form using the Autoform wizard. This wizard creates a form for you automatically by asking you very minimal questions. The form includes all the fields from the selected table.
To construct an autoform tabular.
Creating a form from scratch
To add controls onto the grid:
Data manipulating in a form
Adding and displaying records
The form provides the user with navigation buttons located at the bottom that can be used to navigate the form
The functions of the buttons can be summarized from left to right as follows
Formatting fields/controls in a form
To format fields in a form;
Searching for specific records in a database
One major reason for use of a computerised database is the ability to search and retrieve specific information more efficiently. Rather than searching through endless filing cabinets, you simply enter an instruction and let the database do the rest. To search for data in a database, Ms Access provides the user with two search tools:
Using the find command
With a large database, the Find command saves your time when you need to move a record pointer to a particular record.
To search for a record:
( a) Search All
(b) Search Down to up or
(c) Search up to bottom
(a) Any part of field – As long as a string of characters to be searched are present in a word, then all the words having the string will
be searched e.g. “Berg” finds Berger, inselberg etc.
(b) Whole Field – Searches for the whole field for example, “Berg”
will not return Berger, inselberg but specifically berg if it is in the database.
(c) Start of Field – Specifies that, the searched word should start with the specified search string e.g. “Berg”
(a) Match case – Finds only text that has the same pattern of upper and lower case as the one specified in the Find What box.
(b) Search Field As Formatted – Select (check) to find data based on its display format e.g. ‘a date stored asa number 1/5/98 but
displayed as 05-Jan-98
(c) Search Only Current Field:- Select to search through all records for the current field only.
You can use a wildcard e.g. asterisks (*) if you are not sure of the correct search word that will find all records that match the specified search string. For example, if you wish to search for all names that start with letter “J” in a school database, type J *. All names that start with J e.g. John, Jane Joy, Joyce and James will be displayed.
UsingQueries
Queries are the fastest way to search for information in a database. A query is a database feature that enables the user to display specific records as well as perform calculations on fields from one or multiple tables. You can analyse a table or tables by using either a select query or an action query. However, only the select queries will be discussed in detail in this book
Select query
This is the most common type query used for searching and analysing data in one or more tables. Select query lets the user specify the search criteria and the records that meet those criteria are displayed in a dynaset
Action query
These are queries that are used to make changes to many records once. They are mostly used to delete, update, add a group of records from one table to another or create a new table from another table.
The four types of a action queries found in Microsoft Access are:
Creating a select query
Parts of the query grid
Field row- Fields from a table or tables to be used are arranged in this row. Each field should occupy its column.
Sort row – By clicking the down arrow in the sort cell, you can specify the sort order i.e. ascending, descending or no sort.
Show row – By clicking the Show box, you specify whether to display the field in the query results: When the box is not checked, the field will not be displayed.
Criteria row – This is where you type conditional statement that will be used by the query to display specific records.
Or row – Used to specify an alternative condition e.g. if you want to display records with a field called City with items Nairobi or Embu, type Nairobi in criteria cell and Embu in the Or cell.
To add fields into the query grid:
Specifying the search criteria
In order to search for a particular set of records, you have to enter a conditional statement or statements in the criteria row. For example if you have a table called employees with one of the fields as salary, you can display all the employees earning more than Shs. 5,000, by typing >5000 in the criteria row, salary column.
To define criteria, use either relational or logical operators. Relational operators include less than «), greater than (», greater than or equal to (>=), less than or equal to «=), not equal to «» and equal to (=). Logical operators include AND, OR and NOT.
Use AND to display values in a specific range. For example, to display records from the employees table with salaries above 4000 but less than 6000, type, >4000 AND <6000 on the criteria row in the salary column. All the employees who meet this condition will be displayed.
Use OR if you wish to get either one of two values. For example if you wish to get those employees either in Nairobi OR Embu.
If you want to display data in a particular range use the word Between. For example, instead of typing , >4000 AND <6000, type Between 4000 And 6000.
If you want to list all records except those that you do not want to see use NOT. For example if you type NOT 6000 in the salary column of the employees table, all employees records will be displayed except. those with their salary as 6000.
To display records you are not sure of the field name but at least you can remember a few characters, use LIKE and the wildcards. Wildcards are
special symbols mostly an asterisk and a question mark used in place of other characters. For example, to display all names starting with “Sm” followed by any other character, type Like Sm? Like */*/1993 lists records created in 1993 regardless of the day or month.
Saving and running the query
Sorting the dynaset To sort a dynaset:
Modifying and updating a query
To delete fields from the query grid:
To adjust the column size in a query
To modify a criteria statement ‘select query,
Performing calculations in a query
Unlike tables, queries let the user perform mathematical calculations on numeric data. You can perform calculations in a query by using the Total functions or by creating basic formulas
Creating basic formulae
To create a formula that calculates the total marks in an underlying table e.g. Exams table:
Total: [Math’s) + (Physics) + (Chemistry) as shown in Figure 3.20
| Math’s | Physics | Chemistry | Total: (Math’s)+(physics)+(Chemistry) |
| Exam | Exam | Exam | |
| . | |||
| √ | √ | √ | √ |
Fig. 3.20: Creating an arithmetic expression
Using Total functions .
With a query, you can analyze all records fields using the inbuilt functions such as Sum, Average, Minimum and Maximum etc. To use the total functions:
Sum: Adds all the numerical data items.
Avg; Calculates the mean of all numeric data items in the field column.
Min: Returns the minimum value from the field column.
Max: Returns the maximum value from the field column.
Count: Returns the number of items field column.
Printing a query:
Creating a select query from multiple tables
When you use fields from more than one table in a query, there should be a common link or relationship between the tables. There are three type of relationships
In a one -to – one relationship, for a particular field in one table (the main table), there is only one matching record in the related table and vice versa. In a one -to – many relationships, for a particular field in one table there are several matching records in another table. This is the most common type of relationship. For example, a person may make one order, or several orders. For this instance, there is only one record with that person’s details say in customers’ table, yet there are several records related to the same person in the Orders table.
In a many -to – many relationship, for particular records in one table there are several matching records in the other table and vice versa. This is not very common.
Defining relationship between tables
To create a query based on related tables
Creating reports
Reports are used to summarize and present information from a database. A good database software should enable the user to generate database reports and print them for presentation and distribution. This process is referred to as formal presentations. As with forms, a report layout is also designed by placing controls on to the report layout grid as shown in Figure 3.25.
Parts of a report layout in design view
Report Header-This contains unbound controls that displays title of the report.
Page Header – Contains heading or labels data items to be displayed in every column.
Detail – Holds bound controls that display data items for the table or query it was created from.
Page footer holds a control that is to be displayed on every page such as the page number and date. For example =Now() displays the current date and time as set in the system clock.
Report footer – Used to display summary from a report such as the grand total for numerical data in a particular field column.
Creating a report using report wizard
Just like the form wizard, report wizard takes the user through a number of steps by answering a few questions and Ms Access automatically does the rest.
To create a report layout:
Creating a report in design view
Just like with forms, you can create a report in design view by placing controls on the report design grid.
To design a report in design view:
.’
Modifying a report layout
To modify headers and footers:
To add more controls onto the report layout:
To resize or move a control:
Creating labels
A label is a sticker or piece of paper put on an item for the purpose of identification. Examples of stickers are mailing labels, label on the floppy disk where you write your name etc. Using the report label wizard, Microsoft Access lets you easily create labels of different sizes.
To create a label using the report wizard,
Modifying labels
Just as you can modify a report or a form, you can also modify a label by manipulating the layout controls.
To modify a label,
Printing the report and labels
Before you print a report or a label, you should first set the page options i.e. the margins, paper size and orientation.
DESKTOP PUBLISHING (DTP)
Chapter outline
4.1 Introduction.
4.2 Definition of desktop publishing.
4.3 Purpose of desktop publishing.
4.4 Types of desktop publishing software.
4.5 Designing a publication.
4.6 Manipulating text using the toolbox
4.7 Editing a publication.
4.8 Formatting a publication.
4.9 Printing a publication.
Introduction
Have you ever asked yourself how newspaper and book publishing companies manage to produce publications that are attractive with creative layouts and graphics in large volumes? They do this through a special process called publishing. Publishing is the process of producing publications like newspapers, cards, pamphlets, pictures, calendars etc. that have special text and graphical layouts and designs. The traditional method of publishing involved drawing and writing manually on wooden or metallic boards. The artwork would then be painted with ink and pressed on papers to produce a printout. This was a very tedious work.
Today the art of publishing has changed because of the advent of personal computers and smaller printers that are able to print high quality text and graphics even in an office or at home.
Definition of desktop publishing (DTP)
Desktop publishing refers to the process of producing publications like cards, newspapers etc. by designing their text and graphics layout and inserting, editing, formatting and printing of text and graphical objects using a special desktop publishing software installed on computers. The term desktop means that all the publishing processes can now be done on a desk in the office or at home using a personal computer! The difference between a desktop publisher and a word processor is that a desktop publisher software gives the user more tools and control of the page layout, text manipulation and graphic design than a word processor.
However it is important to note that some word processors today have also been incorporated with text and graphic formatting and editing tools. Hence a thin line exists between them and the desktop publishers. For example you can design a full publication in Microsoft Word by using the available drawing and picture tools, create columns etc.
Examples of desktop publishers include Adobe PageMaker, CorelDraw, Microsoft Publisher and Ventura. This book will use Adobe PageMaker to demonstrate the concepts of desktop publishing.
Purpose of desktop publishing software
Desktop Publishing programs are very popular in publishing because they give the person designing publications (typesetter) a lot of control on:
Graphic design: Using desktop publishing software, a typesetter can create and edit very complex text and graphical objects like pictures to the finest details. For example, the software provides the user with rulers and ruler guides that can be used to place an object in exactly the correct position.
Page layout design: With a desktop publisher, the user can be able to design a page layout by setting consistent picture and object locations, dividing a page in a number of columns and creating layers. A layer can be viewed as the arrangement of objects on top of each other with the one on top being on the first layer e.g. text can be on one layer while graphical objects on another. Therefore the text layer can be manipulated separate from the graphical object layer like for example text moves separate from the objects. Another good example is you can make the graphical object layer transparent in order to make the text in a layer behind the object visible.
Printing: Because the main purpose of any desktop publisher is to produce publication s, this cannot be accomplished without printing. Desktop publishing software therefore helps the user prepare what is referred to as an artwork in commercial circles for printing.
Types of desktop publishing software
There are two main types of desktop publishing software:
Graphical based: They are specifically developed to edit and format graphic objects like pictures. Examples are Adobe Photoshop, Corel Draw, harvard graphic etc. This desktop publishers have superior image handling capabilities like setting resolution, brightness, contrast, cropping and filling images of all types with colour.
Layout based: These types of desktop publishers are specifically developed to create different page layout designs for text and pictures. Have you ever wondered how the complicated front page of a newspaper is developed? It is difficult to achieve such without a good layout based DTP. Good examples of layout based desktop publishers are Adobe PageMaker and Microsoft Publisher.
Designing a publication
Publications vary in design and formatting. For example, a card has a particular design layout that is different from a newspaper. Therefore, publication designs determine how they are classified.
Types of publications
It is possible to produce different types of publications using a desktop publishing software. There are several types of publications that can be published namely:
Cards: These may be for weddings and other special occasions like graduations and for congratulations.
Certificates: To show completion of courses and special events. These type of publications are very sensitive because they must be designed to discourage any type of duplication or counterfeits.
Newspapers, magazines, pamphlets and newsletters: Have news targeting a group of people. They may have many text and graphical layouts and designs.
Books: Are bulky publications with many pages bound together in the same publication.
Calendars: Apart from showing dates, they are used by companies to advertise their products hence most of them have heavy catchy graphics.
Running Adobe PageMaker
Currently PageMaker versions 6.5 and 7.0 are the most common desktop publishing software developed by Adobe PageMaker. Other Adobe products includes Adobe Photoshop mainly used for editing and formatting photographs, Adobe illustrator used for creating complex freehand artwork such as drawings and logos etc.
Starting Adobe PageMaker
PageMaker screen layout .
The PageMaker application window looks like most application windows for programs you have used before. It also has a title bar, menu bar and scroll bars. However, you will note that unlike most of the Microsoft applications you have used before, Adobe PageMaker does not have a status bar on its application window. The most notable difference between a desktop publishing software such as PageMaker and a word-processing software such as Microsoft Word is that a desktop publishing softwarehas its printable work area centered on a pasteboard as shown in Figure 4.2.
The PageMaker publication window is made up of the following layout components:
The pasteboard
A pasteboard is a large blank area where you place text and graphical objects before arranging them neatly on the printable work area enclosed with margins.
The printable area
It is the area that looks like a page surrounded by margins on the pasteboard. Any object or text that is placed on the printable area will be printed by the printer.
The Toolbox.
This is a set of buttons that contains various tools you can use to create and manipulate your publication it has the following tools
Line tool
Rectangle tool
Ellipse tool
Polygon tool
Hand tool
Pointer tool
Rotate tool
Text tool
Cropping tool
Constrained tool
Rectangle frame tool
Ellipse frame tool
Polygon frame tool
Zoom tool
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