# Block diagram of computer

A computer is a device, which is used to manipulate the information or for doing calculations and other tasks, but every task that is given to the computer, is processed in CPU.

### CPU: Central Processing Unit.

The CPU is the brain of a computer. As humans need the brain to complete every task, similarly computers need CPU to complete its tasks. Every task that the user gives to the computer is processed in the CPU.

To explain the processing of the CPU, we have this block diagram. Block diagram gives us a quick overview of its processing.

In this process, there are three steps:

To give input,

Processing in CPU,

Receiving output.

### Units of CPU:

1. Input unit: The information or instructions that the user enters in the computer system is called input. The devices which are used to enter instructions are called input units. Input unit like a keyboard is used for typing input. For example: If we type, “2+2” from the keyboard, it will be the input.
2. Processing in CPU: In CPU there are three units which work together. These units are:-

CU: Control unit

ALU: Arithmetic Logic Unit

Memory Unit

When we give input, first it goes to the Memory Unit, where the information or input is stored.

After that Input goes to CU from the memory unit.

1. CU stands for control unit.

Here the entire operation or processing of the given input is controlled. It obtains the instructions from the memory, interprets them and directs the operation or process of the computer. It also controls all devices such as memory units, input and output devices connected to the computer. In simple words,it controls the given input or instructions by the user to the computer.

1. Then input goes to ALU.

ALU performs all the arithmetic operations such as addition, subtraction, multiplication and division.

It also performs logical operations for comparison.

Like : And or Not,  =,<, > .

It solves the given input or calculations

Like we gave input 2+2 , now it will define it, that it is a calculation, so will be solved in ALU.

When the calculation is done, it proceeds to the next step.

The last step is the output unit. After all the processing, from typing input and processing in CPU, it gives output.

As we gave input 2+2, it was processed in the CPU and we got output 4.

The process goes like, Input  > CPU  >  output .

Input is 2+2  > processing in CPU > output is 4

1. Output units receive information from the CPU and deliver or show it on the computer screen , when we save it, information is transferred to the external storage device. The devices which are used to display output to the user are called output units or devices, like : monitor, printer etc.