THE COMPUTER

1. THE COMPUTER

2. Objectives • Define the computer • Identify the components of the computer system • Describe the function of various hardware devices • Types of computers

3. What is a Computer? • A computer is an electronic device that is capable of accepting instructions and raw data (input), converting the raw data into processed data (information), according to the given instructions (processing), storing the information for future use (storage) and presenting the information (output) whenever it is needed.

4. Components of a Computer System A computer system is a combination of hardware, software, procedures, data and people that create a functional unit.

5. Hardware • This refers to all the tangible parts of the computer – i.e all parts that you can see or touch. These include computer case, monitor, mouse, keyboard and disk drives. • Hardware devices may be classified as being input, output, processing or storage. A few devices may perform more than one function. • Input, output and storage devices are also called peripheral devices. These devices are all connected to the computer’s central processing unit.

6. Hardware - Input Devices • Each part of the computer is called a device. Some of the devices allow you to send messages into the computer system. These are called input devices e.g mouse and keyboard.

7. Hardware – Output devices • Devices that allow message to be sent out of the system, either directly to the user or to another computer. E.g monitor, printer and speakers.

8. Hardware – Storage Devices These devices are used to store information even after the computer is turned off. These storage devices include a hard-disk drive (also called hard drive), floppy-disk drive and recordable CD drive. The storage devices are usually located within the systems unit or computer case. Some of these devices may also be located outside the systems unit.

9. Hardware – Processing Devices • The ‘brain’ of the computer is called the CPU (Central Processing Unit) or processor. • It processes or works on the information in the computer. The CPU consists of three interrelated parts: • The ARITHMETIC LOGIC UNIT (ALU) that performs all the calculations necessary for the computer to operate. • The CONTROL UNIT (CU) directs the flow of data through the CPU and to and from the other devices. • The MEMORY unit holds all of the data and instructions that the computer uses to operate.

10. Hardware - Memory • The memory unit consists of two types of memory: • ROM (Read Only Memory) – permanent and cannot normally be changed. • RAM (Random Access Memory) – memory that can be changed instantly. RAM is erased whenever the computer is switched off.

11. Software • ‘Software’ refers to the programs that allow the hardware and users to do a useful job. Without software, hardware is useless. Software consists of a series of instructions that tell the computer what to do.  • There are two types of software: • System software – E.g Windows Professional 2000, Windows XP and DOS. • Application software – E.g Microsoft Word, Excel, Access and AutoCAD

12. People • These are the users of the computer. It is people who design, build, program, and maintain the computer system.

13. Data • Data consists of raw facts such as numbers, letters, special characters or symbols. These convey little meaning by itself, however, whey they are combined and processed they appear to context and convey meaning to people. • Data is organized into files within the computer. Each file is a set of data that has been given a name. • Computers manipulate and store data in the form of coded electrical impulses called bits.

14. Procedures These are the instructions that tell a user how to operate and use the information system.

15. Communication • The transmission of data from one drive to another or from one program to another, or from one computer to another.

16. TYPES OF COMPUTERS Computer system may be classified according to sizes. The four basic classes are microcomputers, minicomputers, mainframe, supercomputer

17. Microcomputer Also called a personal computer (PC). Designed to be used by one person. A small computer that operates on a microprocessor. It does not have a very large memory and storage system but is used for general purposes in businesses and homes. It is placed on top of a desk (desktop) or rests on your lap (laptop) – small portable computer called a notebook because it can open and fold like a notebook.

18. Microcomputer • A palmtop computer is hand-sized. • A personal digital assistant (PDA) is small handheld device about the size of pocket calculator. It is used for managing schedules and storing contact information. • A workstation is a desktop computer, but with a more powerful processor, extra memory and greater capabilities.

19. Microprocessor • A PC may also be used as a server – a computer that is designed to control a computer network –they have powerful processor, extensive memory and large storage capacity.

20. Minicomputers Sometimes called mid-range computers. They are more powerful than microcomputers and can support a number of users performing different tasks. Originally developed to perform specific tasks such as engineering calculations They increase in capacity. Decrease in size.

21. Mainframe • Large systems that can handle numerous users. • Store large amounts of data and process transactions at a very high rate. • Used in large organisations where many people must access the same data, often simultaneously.

22. Supercomputers • They are the largest, most powerful category of computers. • Most expensive. • Able to process hundreds of millions of instructions per second. • Used for such applications as weather forecasting, space exploration, genetic engineering and other jobs requiring long complex calculations.

23. Books used • Information taken from: • Electronic Document Preparation and Management for CSEC – Ann Margaret Jacob/Agatha Augustine • Electronic Document Preparation and Management - Frank Ramtahal