A digital computer is an electronic data processing machine which takes data as input, processes it, stores it and gives information as output with the help of a set of instruction called a program.

Components of digital computer:-

  • Input unit
  • Memory unit
  • Logical unit 
  • Control unit
  • Output unit

1. Input unit 

The input unit is a device to feed programs and data to a computer.

It links the external environment of a computer system to its internal environment. The programmer has access to the computer through this unit only. thus the input unit performs the following function:-
  • It accepts the data or instructions from the user.
  • It converts these instructions and data in a computer acceptable form that is binary forms.
  • It supplies the converted instructions/data to the computer for further processing.

 2. Memory unit 

This unit is very important in computer because it is this unit which stores data, instruction to manipulate data, and intermediate results. A memory unit can be considered to be consisting of four groups of memories. These are:-

    • Internal Processor memories

    These consist of a small set of high-speed registers that are internal to a processor and used as a temporary location where actual processing is done to enhance computer performance.

    • Primary memory or main memory 

    It is a large memory that is fast but not as fast as internal memory processor memory. This memory is accessed directly by the processor. It contains instruction and data that are accessed by a program while it is executing. The main memory is based mainly on integrated circuits.

    • Secondary memory/ Auxiliary memory  

    Secondary memory is large in size than the main memory but is slower than the main memory. It normally stores programs, other instruction, and data files. Thes are not accessed directly by a processor. First, the knowledge of those recollections is transferred to the most memorable and so the knowledge will be accessed.

    • Cache memory

    It is logically positioned between the internal memory and the main memory. It stores or catches some of the main memory that is currently in use of the processor. Thus to reduces the waiting time of CPU cache is used.

    3. Arithmetic and logical unit

    The part of the computer which performed arithmetic and logical operation is called the Arithmetic and Logical Unit.
    It also controls the speed of these operations.
    Arithmetic and the logical unit is the principal element of the CPU. This part of the computer can add, subtract, multiply, dividend, and is capable of making logical decisions like 'greater than', 'less than', and 'equal to'. These operations are carried out at a very high speed.

    4. Control unit

    This unit is the brain of the computer. It is required to supervise the functioning as a whole. It controls activities of the other unit such as the input/output unit, ALU, etc.
    A control unit works by receiving input information that converts into control signals, which are then sent to the central processor. The computer's processor then tells the hooked up hardware what operations to hold out. The functions that an impact unit performs ar keen about the kind of central processing unit, because of the variance of design between totally different makers. The following diagram illustrates however directions from a program ar processed.

    5. Output unit


    Similar to input unit devices, output devices have an interface between the user and the computer. These devices take machine-coded results that can be used by human beings.
    In personal computers, display screens, printers and plotters, magnetic tapes, and large disk units often accept the output of a large system.
    The output unit performs the following functions:-
    • It accepts the results produced by the computer, which are in coded form.
    • It converts the coded form of result into a human-readable form.
    • It supplies the converted result to the outside world.