Functional units of a digital computer

Functional units of a digital computer

A computer perform five major operations. There are following,

Ø  It accept data or instructions as input.

Ø  It stores data and instructions.

Ø  It processes data as per the instructions.

Ø  It control all operations inside a computer.

Ø  It gives result in the form of output.

Functional units of a digital computer

Functional unit :-

Input unit : This unit is a used for entering data and programs into the computer system by the user for processing.

Storage unit : The storage unit is used for storing data and instructions before and after processing.

Output unit : The output unit is used for storing the result as output produced by the computer after processing.

Processing unit : The task of performance operations like arithmetic and logical operations is called processing.

The CPU ( Central Processing Unit) take data and instructions from the storage unit and makes all sorts of calculations based on the instructions given and the type of data provided. It is then sent back to the storage unit.

The main functional units of a digital computer are given blow:

Ø  Central processing unit ( CPU ) : The CPU is a main part of computer. It is called brain of computer system. CPU takes the data from input devices and processing it according to the set of instructions . This instructions is called program. The output of processing of the data is directed to the output devices for use in the outside world.

             CPU has two major parts :

        i.            ALU

      ii.            Control unit

        i.            Arithmetic logic unit ( ALU ) :  ALU perform the arithmetic operation on data by adding, subtracting, multiplying and dividing and logical operations by using AND, OR, NOT operation which is done by analyzing and evaluating data. An ALU can be designed by engineers to calculate any operation. As the operations become more complex, the ALU also becomes more expensive, takes up more space in the CPU and dissipates more heat. Most of the operations of a CPU are performed by one or more ALUs, which load data from input registers. A register is a small amount of storage available as part of a CPU. The ALU stores the result in an output register.

      ii.            Control unit (CU ) : It manages and controls all the operations of the computer. The mainly used for generating the electronic control signals for the synchronization of various operations. All the related function for program execution such as memory read,  memory write,  I/O read,  I/O write, execution of instruction are synchronized through the control signal generated by the control unit. The control unit tells the ALU what operation to perform on that data.

Ø  Input unit : Input unit perform following functions

It reads instructions, accept instructions and data from outside world. It converts these instructions and data in computer acceptable form. It supplies the converted instructions and data to computer system for further processing. It’s provide by the input device .The input device is also called peripheral devices like as keyboard , mouse, image scanner ,bar-code scanner etc.

Ø  Output unit : The output unit perform following functions,

It accept the results produced by a computer,  which are in coded from. It converts these coded results to human acceptable form ( readable from). output unit is responsible for providing the output in user readable form. It can be text, graphics, tactile, audio, and video.

Ø  Storage unit : A storage unit stores the data. It received the data from input devices. Data and instructions required for processing. A storage unit intermediate result of processing. Result of output,  before they are released to an output device. We store the data in storage unit and use this data when require.