The computers consists of the following functions units.
- Input Unit.
- Central Processing Unit (CPU)
- Output Unit.
During data processing, input unit except data along with instructions for the user and load them into the main memory of the computer. The control unit CU generators the necessary signals and data along with instructions that is transfer from man memory to ALU (Arithmetic Logic Unit) for processing. ALU processes the data accounting to the instructions and transfer the results back to main memory and other peripheral device likes visual display unit, printers etc. The computer performance all the operations under the supervision of control unit. It send the necessary signals to all the peripheral device whenever required.
The following diagram is showing the interaction of functional units :
Block Diagram of Computer
1. Input unit :
Then put unit is used to feed the datas well us interactions to the computer. Data and interactions inter thought input units in the form that dependent upon the particular device used.
For Example : data is entered form a keyboard in manner similar to typing, and this differs from the vein which data is entered throat occurred reader which is another type of input. The commonly used input devices aur keyboard, mouse, joystick etc.
In brief, the following function are performance by an input unit :-
- It accepts aur rates the list of instructions and data form the outside world.
- It converse these instructions and data in computer acceptable form.
- It supplies the converted instructions and data to the computer system for further processing.
Central Processing Unit (CPU) :
The CPU is the brain of any computer system. It is fastest and costely unit of the computer. In a computer system all major calculation and comparison are made inside the CPU and the CPU is also responsible for activating and controlling the operation of other units of computer system. It consists, further three sub parts.
(A) Control Unit :
It works as supervisor or monitor in the system. It controls the function of the computer. Selects interprets and directs the execution of the program instructions. It fetches the required instructions for the man memory, interprets them and then sends them to (ALU) Arithmetic Logic Unit for processing. It control the flow of data to and form the main memory. It acts as a monitor which tells the other components, what to do, how to do and when to do.
(B) Arithmetic Logic Unit (ALU) :
The function of alu is to perform the actual calculation in the computer. It performance arithmetic (addition, subtractions, multiplications and divisions) and logic (comparisons or decision) calculations [eg. IF A < B THEN PRINT A ELSE PRINT B] in the computer. ALU perform the calculation and send intermediate and final result to the man memory.
(C) Main Memory :
The basic function of main memory is to hold the data,. Interaction, intermediate land final results in the system, so that it can deliver them on demand at later time. It also referred as the primary storage. It is a direct taxes stories device, consisting of a number of storage locations. Each location in the storage has a unique number, called address.
There are different type of memories :
(1) Primary Memory/Main memory :
It is of two types Ram [Random Access Memory] and Rom [Read Only Memory].
(2) Secondary memory :
The secondary memory is used to store the data permanently. The user can access the data form secondary memory, whenever required. There are different type of secondary storage devices. CD (Compact Disk), Floppy Disk, Hard Disk, Magnetic Tapes etc.
3. Cashe Memory :
The speed at which the processor execute the instruction is which faster than the speed heat the extractions are transferred from the man memory. In order to make it compatible vi use cache memory. It is small, fast and expensive.
4. Virtual Memory :
Virtual memory is a memory management technique, which is used when man is memory is indequte is the system.
3. Output Unit :
The output unit is used to provide the results to user. The commonly used output and device are monitor, ploter, speaker and printers etc.