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Farrah Zafar · #1 Monday, May 21, 2012

CPU stands for Central processing unit.It is also known as microprocessor or processor.A CPU is brain of a computer.It is responsible for all functions and processes.Regarding computing power,the CPU is the most important element of a computer system.The CPU is consisted of thin layers of thousands of transistors.Each transistor receives a set of inputs and produces output.Transistors hold a key role in functioning of CPU as they make computer able to count and perform logical operations which is called processing.It processes the instructions that it collects by decoding the code in programs.Computers use two types of storage: Primary storage and secondary storage. The CPU mainly interacts with primary storage or main memory,referring to it for both instructions and data.

There are four important functions of CPU,

1)Fetch
2)Decode
3)Execute
4)Write back

Main Components of CPU:

The main components of CPU help it in performing various functions.The components of a CPU work together, and their making/manufacturing determine the complexity of operations as well as how fast they can be carried out.

The three components of the CPU are following,

1. Arithmetic Logic Unit
2. Control Unit
3. Registers

Arithmetic Logic Unit (ALU)

There is electronic circuitry in arithmetic logic unit which executes all airthmetic and logical operations.Its function is obvious from its name.It performs arithmetic calculations like as addition, subtraction, multiplication and division as well as comparisons.The unit can compare numbers, letters, or special characters.There can be more than one Arithmetic logic unit in a CPU, and these ALUs can also be used for the purpose of maintaining timers that help run the computer.

Control Unit(CU)

There is circuitry in the control unit which uses electrical signals to instruct the whole computer system for carrying out or executing,already stored program instructions.Its name clearly shows that it controls and co-ordinates computer components.It extracts instructions from memory and decodes and executes them.In fact it regulates the flow of information through the processor.In short,it can be said ,this component receives, decodes, stores results and manages execution of data that flows through the CPU. Its communication with both arithmetic unit and memory is inevitable.

Registers/The Memory Unit

Registers are temporary storage areas which are responsible for holding the data that is to be processed.They store the instructions and data in a processor.This data is further used by Control Unit.There are some registers that are set aside for specific tasks, these generally include a program counter, stack, and flags.

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