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  1. 1. UNIT 1: FUNDAMENTALS OF COMPUTERLeaning OutcomeIntroduction1.1 Defining a computer1.2 Computer hardware1.3 Computer softwareQuick summaryAssignmentReferencesAt the end of the Unit, you will be able to:• Define a computer• Understand how a computer works• List computer hardware and softwareIn various Modules before this, you have been introduced to the concept of Information andCommunication Technologies (ICTs). Today, ICT has become very important for thedevelopment of any country since it can facilitate and enable people to have access toinformation quickly. ICTs are at the heart of your telecentre.The computer in your telecentre is one of the important ICT tools. It helps you in providingmany critical services to your community. So, it is critical to learn more about the computerand its components. In this Unit, you will be introduced to the basic concepts of computerand its components. Page 1
  2. 2. A computer is an electronic device that operates under the control of a set of instructions. A computer accepts data from an input device and processes it into useful information, which is displayed on its output device. Actually, a computer is a collection of hardware and software components that help you accomplish many different tasks. Hardware consists of the computer itself, and any equipmentconnected to it. Software is the set of instructions that the computer follows in performing atask.1.1.1 Classification of computersComputers can be classified by their size and performance. The size of a computer oftendetermines its function and processing capacity. The size of computers varies widely fromtiny to huge and is usually dictated by computing requirements. Some of the major types ofcomputers are listed below:Supercomputers The largest computers are supercomputers. They are the most powerful, the most expensive, and the fastest ones. They are capable of processing trillions of instructions per second. Examples of users of these computers are governmental agencies, such as the Railway system, the National Weather Service, and the National Defence Agency. Also, they are used in the making of movies, space exploration, and the design of many other machines.Mainframe computersMainframe computers process data at very high rates of speed,measured in millions of instructions per second. They are veryexpensive, costing millions of dollars in some cases. Mainframesare designed for multiple users and process vast amounts of dataquickly. Banks, insurance companies, manufacturers, mail-order Page 2
  3. 3. companies, and airlines are typical users of such computers. Mainframes are often ‘servers’,i. e., computers that control a network of computers.Microcomputers Microcomputers can be divided into two groups -- personal computers and workstations. Workstations are specialised computers that approach the speed of mainframes. Often microcomputers are connected to networks of other computers, whereas a personal computer is a standalone computer. Most of the telecentres use a personal computer.Notebook and Laptop computersA notebook computer can fit into a briefcase andweighs less than two pounds, yet it can competewith the microcomputer. A larger and heavierversion is called a laptop computer.Personal digital assistant The smallest computer is the handheld computer called a Personal Digital Assistant or a PDA. PDAs are used to track appointments and shipments as well as names and addresses. PDAs are also called pen-based computers because they utilise a pen-like stylus that accepts hand- written input directly on a touch-sensitive screen.The computers of all sizes have common characteristics. Some of these are: speed,reliability, storage capacity and productivity. It is capable of storing enormous amount ofdata that must be located and retrieved very quickly. There are two components of acomputer: hardware and software. You will learn about these components in the followingsection. Page 3
  4. 4. Any computer system has two components, namely hardware and software. The physicalequipments connected to a computer system comprise the hardware. The computerhardware is responsible for performing four basic functions: input, processing, output andstorage.1.2.1 Input devicesInput devices send data and instructions to the Central Processing Unit (CPU), which actslike the brain of the computer. You can talk/ communicate with the CPU through the inputdevices. These include, Key board, Mouse, Scanner, etc. Let us learn about each of theseinput devices below:Keyboard The keyboard is probably the most used input device. It operates a lot like a typewriter, but it has many additional keys that let it do special things that a typewriter can’t do.MouseAnother input device is called a mouse, because of it’s shape. The cableattaching it to the computer looks a bit like a tail. When you move the mouse,you’ll see a small moving arrow. This arrow is called the pointer. Using thispointer, you can provide data to the computer for processing.Scanner A scanner is a very useful input device. You can place a page of writing or pictures in the scanner and it will send the information to your computer. There they can be changed, saved into a computer file, or printed.Some of the other input devices are Web camera and the Joystick.1.2.2 Processing devices Page 4
  5. 5. Once information is sent to a computer by one of the input devices, it is processed. Thecomputer uses it’s brain or the CPU to process the information.A processing unit consists of different components, which are bound together into a simplebox called Cabinet. Some of the key processing devices are listed below.Motherboard Your computer couldn’t work without the motherboard. The motherboard ties all the processing components together. It allows every part of your computer to receive power and communicate with each other. Everything that runs the computer or enhances it’s performance is either part of the motherboard or plugs into one of it’s expansion slots or ports.ProcessorThe processor is the main brain of the computer. When preparingthe specification of a computer, one should know the clock rate orclock speed of a computer. It is the fundamental rate in cycles persecond (which is measured in hertz) for the frequency of the clockin any synchronous circuit. The higher the processing speed, thehigher the output.Random Access Memory (RAM) RAM is a temporary memory. The computer holds information in this memory and gets it when needed. If a computer has more RAM, it can solve problems and process information faster. If you’re updating your computer, more RAM is a great thing to add.Hard Disk Drive (HDD)The Hard Disk Drive is a magnetic storage device. All the computerprogrammes and files you create and save are located there. This ispermanent storage. The hard drive is normally signified by the letter “C”.Today’s hard drives can store a huge amount of information.Power Supply Unit (PSU) Page 5
  6. 6. If there is any one component that is absolutely vital to the operation of a computer, it is the power supply. Without it, a computer is just a box full of plastic and metal. The power supply converts the alternating current (AC) line from your home or school to the direct current (DC) needed by the computer.You can see the power supply from the back of your computer because of the power cordand the cooling fan. Computers generate a lot of heat and need the fan to keep them coolfrom overheating.1.2.3 Output devicesAn output device displays the processed information to the user. Some of the prominentoutput devices are Monitor, Printer, Speaker, etc.MonitorThe monitor looks like a TV and lets you see your work and files. The monitor producesoutput that is temporary—the output is lost when it is rewritten or erased or when power islost. The Monitor output is called the softcopy.PrinterThe printer displays output in a permanent manner; it is called the hardcopy. The printerprints exactly what’s displayed on the screen of the monitor.SpeakerSpeakers can be connected to your computer, so that you can hear very realistic soundeffects and wonderful music. Some computer monitors come with built-in speakers.1.2.4 Storage devicesThe secondary storage devices store data and programmes permanently. These include CD/DVD-ROM, Pen drive, External Hard disk, etc.CD/ DVD-ROM Page 6
  7. 7. CD-ROM stands for Compact Disk-Read Only Memory. They are flat, shiny disks that storeinformation. Most new computers have CD-RW drives. CD-RW stands for Compact Disk-ReWrite. This type of disk allows you to write information to it, as well as read from it. Mostof them can hold up to 700 megabytes of information.The newest computers come with the option of a DVD drive. A DVD (Digital Video Disc)looks just like a CD, but holds much more information. They can store 4.7 gigabytes ofdata.Pen driveThe pen drive is a portable USB flash memory device that can be used to quickly transferaudio, video, and data files from the hard drive of one computer to another.External hard disk driveAn external hard disk drive is a type of hard disk drive connected to a computer by a USBcable or other means. It can be easily carried and used in any computer.The hardware devices may be very important, but they are useless without the instructionsthat control them. These instructions that are used to control hardware and accomplishtasks are called software. In computers, software is anything, but hardware. Software canbe categorised into the following three main types:i. System softwareii. Programming softwareiii. Application software1.2.1 System SoftwareSystem software acts as an interface between hardware and computer applications in acomputer. The system software includes Device Drivers and Operating System in acomputer. Device Drivers specifically integrate Operating system and Hardware Devices,such as scanner, webcam, Hard Disk Drive, etc. Page 7
  8. 8. Operating SystemAn operating system of a computer, which comes under System Software class, interfacesbetween hardware and the user. It coordinates resource allocation for computerapplications, which run on a computer and coordinates and manages activities of acomputer. Some of the popular operating systems are different UNIX flavours, Linux,Microsoft Windows, Mac, etc.1.2.2 Programming softwareProgramming software provides tools to assist programmers to write computer applicationprogrammes. Programming software includes compilers, debuggers, linkers etc.1.2.3 Application SoftwareApplication Software allows end user to run applications, which allow them to carry out oneor many tasks. Some of the most popular general applications are Open Office and MicrosoftOffice, which also includes financial applications and accounting packages. Page 8
  9. 9. 1. Miller, Michael (2002), Absolute Beginners Guide to Computer Basics, Que: USA2. White, Ron and Downs, E. Timothy (2003), How Computers Work, Que: USA3. Wikipedia resources on computers ( Page 9