Components of a Computer System

There are few main components that are required to make the computer functional. These components are :

1. Input Unit
2. Central Processing unit     
3. Primary Memory (Main Memory)
4. Secondary Memory
5. Control Unit (CU)
6. Arithmetic Logic Unit (ALU)

You can understand the working of computer by using the following diagram :

Input Unit (Keyboard, Mouse, etc.) gives the input to the CPU (Central Processing Unit). This CPU consists of CU (Control Unit), Memory Unit, ALU (Arithmetic logical Unit). Control Unit Controls all the Operation inside the CPU, Memory Unit is used to store the intermediate result and ALU performs the Arithmetic and Logical Operations. Finally the Output will be sent to Output Unit (Monitor, Printer, etc.) . Here are the steps that is followed by any computer for processing :

1. Input Unit give the Input to the Control Unit of CPU(central Processing Unit. (This Control Unit Controls the Operation inside the CPU. It takes necessary actions for execution of any operation.)
2. Control Unit then send the signal to Memory Unit to take the Data from Hard Disk (Secondary Memory) and Store it in RAM (Primary Memory). (Memory Unit comprises of RAM - Random Access Memory and Secondary Memory-Hard Disk).
3. After receiving the data from Hard Disk the RAM sends Signal to Control Unit, which then connects with ALU and asks it to perform the Operation with the help of Memory Unit.
4. After performing the operation and getting the result the ALU, sends the Signal to Control Unit that the result is ready and Stored in RAM.
5. Then Control Unit send the Signal to Output Device that the result is ready in Memory Unit and Collect it from Memory Unit.
6. Now the Output Unit Gives the Output.

Input Unit -: 

• We give to input through Input device like keyboard or mouse,Then entering data according to user instruction.
• It accept the data and instruction.
• It covert the data and instruction to computer format.
• It converted data and instruction to the computer for further Processing.

Central Processing Unit -:

• C.P.U. is the brain to computer.
• C.P.U is responsible for all processing inside the computer.
• C.PU. is perform all arithmetic and logical operation.
• C.P.U is given  data and instruction through programs.
• C.P.U. stores the result back to memory.

Primary Memory -:

• Primary memory stored data and instruction.

Secondary Memory -:

• Secondary memory kept data and programs long term basis.

Arithmetic Logic Unit -:

• Data entered the computer is sent to RAM from where it is then sent to A.L.U.
• A.L.U. performs the all arithmetic (Addition,Subtraction,Multiplication,Division )  and logicical operation(<,>,=,<=,>=!) inside the computer.
• A.L.U. perform this operation and send data to Control unit (Main Memory).

Control Unit-:

• C.U. accept  (when data send to A.L.U.) the data  and working on decision making.
• C.U. is responsible for selecting , Interpreting , and execution Program.
• C.U. is decide to  "When data received , Where data send ,Where data execute".
• C.U. sent final result to output device.

Output Unit -:

• It accept the result produce by the CU.
• It supplied the result and information to the outside world. 
• Output device is convert to digital operation into human understandable format.

Register -:

• C.P.U stores the data as well as instructions in its local memory 
• Register is the part of C.P.U. Chip.
• Register are used for storing data , instruction and result.