The parts of a computer system

ComputerInputOutput StorageDataInformation HardwareSoftwarePeripheral Main memory Control Unit Central Processing Unit Arithmetic andLogic Unit

A computer is a programmable electronic device that processes data following a set of instructions. An example of a fairly simple computer is a calculator: it can process data and output the information from the processing.

Data is all the raw facts and figures that a computer processes by following a set of instructions called program. Data by itself has no meaning; it can be in the form of letters (a, x, t, etc), numbers (1, 4, 7, 534, etc), pictures, sounds or symbols. It is only when we attach meaning to data that we get Information.

To process data to produce information, a computer needs both hardware and software. Hardware is called the parts of the computer system you can see and touch. It is all the devices that make up the computer system. These devices are also called peripherals devices.

Software is a set of instructions that a computer needs to carry out its tasks. For example, if you want to use the computer to type a letter, or draw a picture you need different types of software to accomplish these tasks. Eg. Word, Excel, Paint, Spider solitaire, FreeCell, Minesweeper, etc

Input Output Process Input Output

Processing data to get information involves three stages. These are input, processing and output.

Input devices such as are used to get data and instructions into the computer for processing.

The processing takes place in that part of the computer called the Central Processing Unit (CPU). The CPU is the ‘brain’ of the computer. It takes the raw data and turns it into information.

The CPU is made up of two smaller units. These are the Control Unit (CU) and the Arithmetic and Logic Unit (ALU). The Control Unit (CU) is the main part of the CPU. Input is first sent to the CU, from where it is then sent to the allocated part of the computer to be processed. The CU decided where to send data to be processed. After processing, the information is returned to the control unit.

The Arithmetic and Logic Unit (ALU) performs all the arithmetic and logic functions in a computer. This involves addition, subtraction, multiplication or division or the comparison of data. Some of the logic functions are comparisons such as: Equal to =Less than < Less than or equal to Greater than or equal to >= Not equal to <>

The main memory, which is directly accessible to the CPU, holds data and instructions that the computer is processing at the time.

Output devices such as printers, speakers and visual display units translate information processed by the computer into a form which the user can understand. After processing, the data and information can be either stored in a secondary storage device, such as a disk, or sent to an output device, or both.

Storage refers to media and devices used by a computer to keep data and instructions available for immediate or later use. Storage can be grouped into two categories: primary storage and secondary storages. All input, output and external storage devices are collectively called peripheral devices.

1. Speed – computers are very fast; they can perform tens of millions of operations per second. This capacity can be useful for operations such as predicting weather, performing scientific research and producing thousands of bills for utility companies.

2. Accuracy – computers are very accurate. Error only occurs if there is an error in the hardware, software or data.

3. Storing large amount of information in a small space – there are many storage media that can be used to store large volumes of data and information. Eg. CD, DVD, Flash drive, Hard disk drive 

4. Working continuously – computers can work continuously for long periods without much maintenance. Many computers are permanently switched on!

1. Find two other definition of a Computer. 2. List 2 other Input, Output and Storage devices not mentioned in the notes.

A H G F B C E D

2. For each part say whether it is an input, an output or a process device: A H G F B C E D

3. Explain the following terms and provide an example for each: a. Input device _____________________ b. Output device _________________________

4. State whether the following are hardware or software: a.Scanner ____________________________ b.Microsoft Word 2003___________________ c.Speakers____________________________ d.Microsoft Windows XP__________________ e.Compact Disk (CD)____________________ f.Internet Explorer______________________ g.Diskette_________________________