From WikiEducator
Jump to: navigation, search


Icon objectives.jpg
By the end of this unit, you should be able to:
  1. Define a Computer System in your own words
  2. Identify the various components of a computer
  3. Name some of the personnel that work in a computer organization.

Icon preknowledge.gif


No previous knowledge of Computers, though it is assumed the reader/student is in contact with some modern gadgets

Icon key points.gif
Key points
Following the concept of the computer being defined as "a system of deevices that can accept data from a user, process the data according to a set of instruction, and gives out information as output". Based on this concept, we usually divide a computer into four main parts,


  • The Input Device
  • The Output Device
  • The Central Processing Unit (CPU) and
  • The Memory

The parts are connected as shown in the diagram below:

Icon define.gif
  • A SYSTEM is a set of inter related components aimed at goal achievement. A Computer system is made up of component parts which must all be configured together to work properly.
  • THE COMPUTER is a system. It is made up of the following components.
  1. Hardware
  2. Software and
  3. Liveware (Human Resources)
  4. The HARDWARE includes all equipment and physical devices made of electronic and mechanical parts which we can actually see or touch. Hardware devices exist for each of the basic input, processing, output and storage functions. As discussed earlier in this unit, this would include the Keyboard, the Printer, the Card Reader etc.
  • The INPUT device accepts data in a form that the machine can recognise and transfers such data into the central processing unit. The input device when we use cards is called a CARD READER. A KEYBOARD, similar to that of the Typewriter is also used on a computer to Input data. It is an input device.
  • The OUTPUT device is used to receive data from the Central processing unit and produce it in a form that a human being can understand or in a form that a computer can receive as re-input. The Visual Display Unit (VDU), similar to a Television screen, on a computer is an output device. The PRINTER, used for printing out processed data, is an output device. In general, anydevices attached to CPU are called PERIPHERALS to indicate that they belong outside the ‘heart’ of the computer. They are more or less appendages, like the hand or the leg.
  • The memory also called the Main memory, internal memory or mainstore is where instructions and data to be processed resides. It is generally regarded as Random Access Memory (RAM). This memory holds instructions and data temporarily while the computer is operating. When the computer is turned off, this memory is wiped. For this the Main storage is said to be “volatile.” The memory of a modern-day computer is made of semi conductor chip(s). A CHIP consists of thousands of electronic components. When an electric pulse is sent to an electric component, it can put the component in one of two states, either a ‘0’ state or a ‘1’ state. A component can therefore be used to represent a binary digit or BIT. Bits are grouped together to form words. The main memory of a computer consists of a number of chips which together hold thousands of words.

You will learn more about BITS in the next lesson.

  • The Backing Storage, also called the Secondary Storage supports the Main storage by permanently holding data and instruction for later use, when needed they are copied into the main memory for processing after which it may be copied back to the secondary storage. The common backing storage devices include magnetic tapes, magnetic disks and floppy disks.
  • The CENTRAL PROCESSING UNIT (CPU) is the device which stores and processes data. It is normally subdivided into the CONTROL UNIT (CU) and the ARITHMETIC/LOGIC UNIT (ALU). The control unit is responsible for the control of the actions of the input device, the main and secondary memory. the arithmetic! Logic unit and the output device. It is like the human brain which control the eyes in. for example. reading the numbers on a calculator and also controls the finger in pressing the appropriate calculator key.

Icon activity.jpg
  1. Define Computer using your own words but with the basic compnents of the system well explained
  2. Distinguish between the functions of the memory and the CPU
  3. Why is the secondary storage important as part of a computer?