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INTRODUCTION TO
MICROCOMPUTER AND
APPLICATIONS
(CIT 100)
Contents INTRODUCTION TO MICROCOMPUTER AND APPLICATIONS .................................................... 1 (CIT 100)................................................................................................................................. 1 Contents................................................................................................................................. 1 CHAPTER ONE: INTRODUCTION TO COMPUTER....................................................................... 2 CHAPTER TWO: COMPUTER SOFTWARE................................................................................ 43 CHAPTER THREE: WORD PROCESSING SOFTWARE............................................................... 63 CHAPTER FOUR: ELECTRONIC SPREADSHEET SOFTWARE..................................................... 80 CHAPTER FIVE: COMPUTER NETWORKING.......................................................................... 102 CHAPTER SIX: COMPUTER VIRUSES..................................................................................... 120
CHAPTER ONE: INTRODUCTION TO COMPUTER
We are living in an information age dependent upon digital information. Digital information is an electronic information result of computer processing. Every type of job relies upon getting information, using it, managing it, and relaying information to others. Computers enable the efficient processing and storage of such information. Do not think of a computer merely as the machine with the keyboard and the mouse, although that might be true for some types of computers. Embedded computers may be inside your household appliances, the Video Cassette Recording ( VCR ), the automobile, planes, trains, power plants, water purification plants, calculators, and even inside a few toys. These embedded computers are very small. They affect our lives each day. They are all around us; even modern traffic lights operate with computers. Think of additional ways in which computers affect our lives each day. Be in any organization, office, factory or institution, you can find people making use of computer for different purposes. For example in offices, computers are used for preparing letters, documents and reports. In hotels, computers are used for advance booking of rooms, preparing bills and providing inquiry services. In railways, computers are used for rail reservation, printing of tickets and preparation of reservation charts. Doctors use computers for diagnosing illness and treatment of deceases. Architects use them for map designing and city planning. In meteorology
get tired after sometime and the chances of making mistakes start getting high as the time passes by. So you can say that computers are capable of performing error free tasks efficiently for the duration, which is beyond human capabilities. 1.2 Computer generations Thousands of different computers have been designed and built during the evolution of the modern digital computer. Each of these computers has been classified into generations. This section tries to highlight the computer generations. First Generation - 1940-
- The first computers used vacuum tubes for circuitry and magnetic drums for memory.
- Were often enormous, taking up entire rooms.
- Generated a lot of heat, because they were very using a great deal of electricity, which was often the cause of malfunctions.
- First generation computers relied on machine language to perform operations they solved only one problem at a time. Second Generation - 1956-
- Transistors replaced vacuum tubes, Transistor is a device composed of semiconductor material that amplifies a signal or opens or closes a circuit.
- The transistor was invented in 1947 but did not see widespread use in computers until the late 50s. The transistor was far superior to the vacuum tube,
- This technology allowed computers to become smaller, faster, cheaper, more energy-efficient and more reliable than their first-generation predecessors.
- Though the transistor still generated a great deal of heat that subjected the computer to damage, it was a vast improvement over the vacuum tube.
- Second-generation computers still relied on punched cards for input and printouts for output.
- Second-generation computers moved from cryptic binary machine language to symbolic, or assembly languages, which allowed programmers to specify instructions in words.
- High-level programming languages were also being developed at this time, such as early versions of COBOL and FORTRAN.
- These were also the first computers that stored their instructions in their memory, which moved from a magnetic drum to magnetic core technology.
- The first computers of this generation were developed for the atomic energy industry. Third Generation - 1964-
- The development of the integrated circuit was the hallmark of the third generation of computers. Transistors were miniaturized and placed on silicon chips, called semiconductors, which drastically increased the speed and efficiency of computers.
- In both cases, the higher the value, the more powerful the CPU. For example, a 32-bit microprocessor that runs at 50MHz is more powerful than a 16-bit microprocessor that runs at 25MHz.
- What in the first generation filled an entire room could now fit in the palm of the hand. The Intel 4004chip, developed in 1971, located all the components of the computer - from the central processing unit and memory to input/output controls - on a single chip. Fifth Generation (1985 - Present)
- The changes that have occurred since 1985 are plentiful. Computers have gotten tinier, more reliable, and many times faster.
- Computers are mostly built using components from many different corporations. For this reason, it is easier to focus on specific component advancements.
- Intel and AMD are the main computer processor companies in the world today and are constant rivals.
- There are many different personal computer companies that usually sell their hardware with a Microsoft Windows operating system preinstalled. Apple has a wide line of hardware and software as well.
- Computer graphics have gotten very powerful and are able to display full three dimensional graphics at high resolution.
- Nvidia and ATI are two companies in constant battle with one another to be the computer graphics hardware king.
1.3 Types of Computers Computers can be classified into various categories, on the basis of their sizes. When we say, size of the computer, it refers to multiple factors like, size of the memory, number of terminals that can be connected to the computer, size of the hard disk, type of processor used in the computer etc. Computers are generally classified into following categories:
- Microcomputers
- Minicomputers
- Mainframe computers
- Supercomputers 1.3.1Micro Computers Microcomputer is the smallest category of computers, in which single microchip is used for two basic units i.e. ALU and Control Unit. This microchip is often referred to as microprocessor. Microcomputers are further classified into following categories:
- Personal computers
- Laptop computers Personal Computers (PC) Computers that we commonly see these days in offices, hotels, restaurants etc. are examples of Personal Computer. In short they are called PC. Outward appearance of PC is shown in figure 1.0. PC mainly comprise of four units i.e. chassis (also called CPU box), keyboard, VDU and mouse. Only one person can work on it at a time. This is the reason why PCs are called single user computers. Originally PCs were designed and manufactured by IBM. Later,as
Figure 1.1 Laptop Computer 1.3.2 Minicomputers Minicomputers are relatively larger and faster computers. They support multi user environment. They are generally used for automating those applications, which are large in size, require fast processing capabilities and demand for resource sharing among multiple users. Main characteristics of Minicomputers are described below:
- They are built, using high performance and high capability processors.
- Memory size, in such type of computers is generally very large.
- They support multiple terminals connectivity, which may range from 2 to 128.
- Large capacity disks are used in multiple numbers so that the data and programs of all the users could be put on-line.
- They provide facility to connect multiple printers.
- They possess the capability of performing computer network related operations.
1.3.3 Mainframes Mainframes fall into next higher category of computers. Their internal architecture and circuitry remains different from Minicomputers. They use specially designed proprietary circuits instead of just single microprocessor as their CPU. Their circuitry promotes higher connectivity, faster throughputs and large data processing capabilities. Due to proprietary circuitry, Mainframes become quite big in size and provide facility for connecting Minicomputers and microcomputers with them. Few characteristics of Mainframes are listed below:
- They possess the capability of addressing larger memory sizes than that of Minicomputers.
- They also support larger capacity disks like optical disks etc.
- Their terminal connectivity can go as high as 256 or beyond.
- They possess large number of application libraries that provide great help to developers in developing useful applications. DEC 20, IBM 370 etc. are the examples of few mainframes. IBM (USA) is the largest manufacturer of Mainframes. 1.3.4 Supercomputers Supercomputer is the largest category of computers. They use multiple CPUs for processing the data and executing the instructions. While performing a task through Supercomputer, the complete task gets divided into multiple independent tasks. Each CPU performs individual task and completes it in parallel. This methodology of processing is called parallel processing.
Each of this operation is performed by specific unit in the computer. This section will give an explanation and organization of each unit of the computer. Before we discuss each unit let us define the term hardware as part of computer system. The term computer hardware refers to the physical components of a computer, i.e. all the components that you can physically see and touch namely: keyboards, CPU, monitors, drives (hard disk, CD, DVD, floppy, optical, tape, etc...), mouse, printers, modems, scanners, digital cameras and cards (sound, color, video ). Computer hardware is an integral part embedded in all modern day automobiles, microwave ovens, electrocardiograph machines, compact disc players, and other devices. In fact computer hardware without software is useless; it is the software that instructs it to perform a particular task As you know, computer is an electronic device, it comprises of many units. These units work in coordination with each other to perform the given task. Block diagram of computer is shown in figure 1.2. Referring to this figure we note that computer comprises of following units:
- Input Unit
- Central Processing Unit (a) Memory Unit (b) ALU (c) Control Unit
- Output Unit
- Input/Output Unit
Therefore a computer system is defined as a device that accepts input, processes, stores, and produces output. Physically the units exist in the form of electronic devices which can be seen and touched. Generally a computer system is made up by Hardware and Software. Each unit performs its own function, in coordination with other devices to perform the given task. What is the role of each unit and in what form do they physically exist, will be explained in the following subsections. Figure 1.2 Computer units 1.4.1 Input Unit Computer receives data from user through input unit. An input device is any hardware component that allows a computer user to transfer information or data, programs, commands, and user responses into a computer system. In general the role of input unit in computer is to provide means for supplying data or instructions to the computer. In other words, you can say that what you supply to the computer for processing is supplied through input unit. For
when you press 'A' key, 'a' gets typed. To type the alphabet in upper case, you need to press Shift key along with the alphabet key. For example, if you press 'A' key along with Shift key, letter 'A' gets typed. Number keys Number keys have digits, from 0 to 9, written on them. These keys are used for typing the numbers. Note that each number key also has a special character written just above the number. To type this character, you will have to press the number key along with the Shift key. For example, number 5 key has % sign marked on it. When you press number 5 key, 5 will get typed. If you pres the combination of same key and Shift key ‘%’ sign will get typed. Special character keys Few keys of the keyboard have special characters like semicolon (;), comma (,), dot (.) etc. marked on them. Such keys are called special character keys. When you press special character key, character marked on it gets typed at current cursor position. Function keys There are 12 function keys present on the keyboard. They are named as F1, F2, F3 …..F12. When you press these keys they perform special functions depending on which program your working with. Cursor keys Four cursor keys are there on the keyboard. They are marked with arrows on them, pointing in four different directions. Using cursor keys, you can move the cursor from one place to another.
Action keys Keyboard has many action keys. When you press an action key, a special event takes place. Most commonly used action keys of the keyboard are described below. Caps Lock Key : When you press this key, capital lock becomes on. When you press an alphabet key, while caps lock is on, the letter written on it gets typed in upper case. Shift key : Always this key is pressed in combination with other keys. When you press this key along with number key then the symbol written on upper part of the key gets typed. When you press Shift key along with alphabet key then the alphabet gets typed in upper case. Ctrl key : The Control (Crtl) key works like the Alt key. It is always used in combination with some other key. Esc key : The Escape (Esc) key is used to escape or leave some function you have selected. The Escape key is always used by itself. Currently on-going activity gets cancelled when this key is pressed. Page Keys : There are two page keys on the keyboard, named as PgDn (i.e. Page Down) and PgUp (i.e. Page Up). When you press PgUp key, previous page gets displayed on the screen. When you press PgDn key, next page gets displayed on the screen. Enter key : The Enter key is typically used to end a paragraph when working in most application programs or to execute a command, also it used as okay tool.
Figure 1.3 Computer Mouse Pressing buttons of mouse is known as clicking of mouse. The mouse is placed on flat surface and moved around to move its controlling arrow on screen. The arrow showing the position of mouse on screen is known as mouse pointer as shown in figure 1.3. Left button of mouse is used execute the operation associated with it. Right button/Middle buttons are associated with special operations in different situations. In old technology mouse has a round ball under the bottom that rolls and turns two wheels which control the direction of the pointer on the screen while the currently mouse uses an optical system to track the movement of the mouse. Figure 1.4 Mouse Pointer
Note: It is important to clean the mouse periodically, particularly if it becomes sluggish. A ball type mouse has a small circular panel that can be opened, allowing you to remove the ball. Lint can be removed carefully with a tooth pick or tweezers and the ball can be washed with mild detergent. A build up will accumulate on the small wheels in the mouse. Use a small instrument or finger nail to scrape it off taking care not to scratch the wheels. Track balls can be cleaned much like a mouse and touch-pad can be wiped with a clean, damp cloth. An optical mouse can accumulate material from the surface that it is in contact with which can be removed with a finger nail or small instrument. What is the mouse and its pointer used for? The mouse and its pointer can be used to do many things. Sometimes when you turn on your computer, there you can use your mouse to point to one of the program you want to use from the start menu. Sometimes when you turn your computer screen on, you see a series of pictures called icons. A popular program with icons is Windows. You can use the mouse to choose one of these pictures to run the program being presented. Usually, picking a picture allows you to start a program or do something within a program. How do you use the computer mouse? By moving a mouse with your hand, you can make the pointer move around a computer screen until you are ready to point at an object. Usually you will find that a computer mouse has two/three buttons. The button on the left is the one
