COMPUTER

This unit can store instructions, data, and intermediate results. This unit supplies information to other units of the computer when needed. It is also known as internal storage unit or the main memory or the primary storage or Random Access Memory (RAM).

Its size affects speed, power, and capability. Primary memory and secondary memory are two types of memories in the computer. Functions of the memory unit are −            It stores all the data and the instructions required for processing.

•        It stores intermediate results of processing.

•        It stores the final results of processing before these results are released to an output device.

•        All inputs and outputs are transmitted through the main memory.

Control Unit

This unit controls the operations of all parts of the computer but does not carry out any actual data processing operations.

And the control unit of a CPU controls the entire operation of a computer. It also controls all devices such as memory, input/output devices connected to the CPU.

CU fetches instructions from memory, decodes the instruction, interprets the instruction to know what the task are to be performed and sends suitable control signals to the other components to perform for the necessary steps to execute the instruction.

Functions of this unit are −

•        It is responsible for controlling the transfer of data and instructions among other units of a computer.

•        It manages and coordinates all the units of the computer.

•        It obtains the instructions from the memory, interprets them, and directs the operation of the computer.

•        It communicates with Input /Output devices for transfer of data or results from storage.

•        It does not process or store data.

ALU (Arithmetic Logic Unit)

This unit consists of two subsections namely,

•        Arithmetic Section

•        Logic Section

Arithmetic Logic Unit (ALU)

Here arithmetic logic unit performs all arithmetic operations such as addition, subtraction, multiplication and division. It also uses logic operation for

-      Arithmetic Section

Function of arithmetic section is to perform arithmetic operations like addition, subtraction, multiplication, and division. All complex operations are done by making repetitive use of the above operations. -         Logic Section

Function of logic section is to perform logic operations such as comparing, selecting, matching, and merging of data.

The information fed through the input unit is stored in computer's memory for processing and the final result stored in memory can be recorded or display on the output medium.

Memory Unit

Memory unit is an essential component of a digital computer. It is where all data intermediate and final results are stored.

The data read from the main storage or an input unit are transferred to the computer's memory where they are available for processing.

This memory unit is used to hold the instructions to be executed and data to be processed. Two types of storage unit are primary and secondary storage unit.

Primary/Main Storage Unit

Primary memory has direct link with input unit and output unit. It stores the input data, calculation result.

Secondary/Auxiliary Storage Unit

The primary storage is not able to store data permanently for future use. So some other types of storage technology is required to store the data permanently for long time, it is called secondary or auxiliary storage.