Computer Studies Notes

Basic Computer Concept

Definition of Computer:

Computer can be defined as a combination of electronic and electro-mechanical devices that are capable of accepting data or information , processing it, storing or providing output under the control of sets of Instructions called programs.

Description of a Computer as Input Process Output (IPO) Device The following pictorial representation shows how the computer is functionally organized to perform all the stages involved in Data Processing (Input process output) as described in the figure below.  

IPO Cycle - YouTube

The parts of computer are:

  1. Input Devices: These are the devices with which one can send data and information into the system. The most common input devices are  keyboard,  sensors and joystick, mouse & pad,  scanner multimedia microphone, light pen, web camera, touch screen .
  2. Processing Device: This is also called the processor. It is the brain of the computer system that works on  the data supplied from the input devices. The processor and all other parts form what is called the Central Processing Unit. The CPU is housed by a casing or box that may be horizontal (desktop) or vertical (tower

top) called the system unit and mounted on the mother board. A processor is the logic circuitry that responds to and processes the basic instructions that drive a computer.

The Central Processing Unit consists of three units: Control unit, Arithmetic  Logic unit and Memory unit.   

(i) The Control unit:  It coordinates  and directs the activities of other elements of the system as directed by the program in store, and also directs control signal between the CPU, input and output devices.

(ii) The Arithmetic and Logic Unit: It consists of two units; the arithmetic unit which performs arithmetic operations such as addition,subtraction, multiplication and division.the logical unit performs logical operations such as the comparison of data e. g greater than(>, less than (<)or equal to (=)

(iii) The Memory Unit: otherwise known as Main Memory is used for storing data to be processed and the instruction for processing.


  1. What is Computer?
  2. State the three parts of a computer.

Types of processor

There are two primary manufacturers of computer microprocessor; Intel and Advanced Micro Devices (AMD). Intel’s desktop CPUs include Celeron, Pentiom and Core, AMD desktop processors include sempron, Athlonan Phenom. Intel makes Celeron M, Pentium M and Core mobile processors for notebooks.

AMD makes mobile versions of its Sempron and Athlon as well as the Turion mobile processor which comes in Ultra and Dual-Core versions. Both companies make both single-core and multi-core processors.  

Features of the Processor

Each processor has a clock speed which is measured in gigahertz. A processor also has a front side bus which connects it with the system’s random access memory (RAM). CPU also has two or three levels of cache.

Cache is a type of fast memory which serves as a buffer between RAM and the processor.                                                                                      

Function of the processor

A processor is a silicon chip containing millions of microscopic transistors which processes the instructions or operations contained within executable computer programs. The rate at which information is processed by the Central Processing Unit varies and depends on the processor speed and available Random Access Memory size.

  • Output Devices : the output devices display or provide the result of the processed inputs either on the Monitor (VDU) or through other output devices some of these output devices are Monitor, Printers, Projector, Plotters, Multimedia Speaker etc.

Hardware of a modern Personal Computer

  1. Monitor
  2. Motherboard
  3. CPU
  4. RAM Memory
  5. Expansion card
  6. Power supply
  7. Optical disk drive
  8. Hard disk
  9. Keyboard
  10. Mouse


We have learnt that computer is an electronic device that consists of the input unit that accept data, process             the data in the system unit and produces the result through output devices.


  1. Define computer as an IPO system.
  2. List the three units of a central processing units.


  1. The operation of the computer system is coordinated by a unit called ____ (a) memory unit (b) processing unit (c) storage unit (d) arithmetic and logic unit
  2. The part of the computer that displays the result of the processed data is called ____ (a) input unit (b) output (c) control unit (d) ALU
  3. The processor’s speed is measured in __ (a) megahertz (b) kilobyte (c) gigahertz (d) byte
  4. ____ is the device used in sending data and information into the system (a) processor (b) input (c) output (d) storage.
  5. ____ is used for storing data to be processed and the instruction for processing.(a) memory (b) control (c) output (d) CPU


  1. What is central processing unit?
  2. List and explain the three units of a CPU.

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