What Is CPU

What Is CPU ?

How CPU Works | CPU Functions | Definition

Microprocessor | Central Processing Unit | Processor

The CPU stands for,  Central  Processing  Unit  ( also referred as Microprocessor , Processor or simply functions as a brain of the system .

The C P U is one the most important component that works as processing engine and the work horse for the  computer system.

It is the central processing unit that takes logical decisions and perform all the calculations necessary to execute any program on the system.

It is the microprocessor ,  that actually provides the processing power to the computer system. The processor works at very high speed and performs millions of calculations per second  in order to execute any program.

In this article , you will learn , what is CPU ? , How processor works ? , Functions Of microprocessor and other important topics related to the central processing unit.

What Is Central Processing Unit ?

What Is CPU ?

The computer systems are extensively used for various applications  primarily due to its ability to process large volumes of data at very high speed . The computer system gets this ability due to an internal  component called Central Processing Unit.

The CPU is an electronic component that is packed with integrated circuit ( IC ) chips . The CPU controls all the operations performed by the computer system. The C P U is also responsible to execute the computer program.

What Is Central Processing Unit ( CPU )

The C P U provides the processing power to the computer system . The computer hardware technology is growing at fast pace and new processors are being introduced in the market with significant improvement in the processing power.

The famous Moors law had predicted this rapid advancement in the computer hardware technology long back  especially in the processing power of the C P U. As per this law , the C P U processing power will double every two years.

The commercial name of the C P U is “Microprocessor” or simply a processor. The  CPU is said to be the  brain of the computer system . The C P U performs all  the arithmetic  calculations  and  logical  operations to perform various operations.

The C P U market is dominated by two players . That is Intel and  AMD. These two U S companies produce and control most the processor market.

What Is Microprocessor ?

CPU Architecture

In order to understand the CPU architecture and the functions of internal components of the C P U , we need to first discuss , how C P U executes a program.

The Operating System ( OS ) loads the program to be executed into the main memory RAM. The C P U starts the program execution by fetching the data and program statements from the main memory into the C P U memory unit.

The C P U operates on the data as per the program instructions and stores the processed data back into the main memory RAM . The operating system sends this data to the output device such as monitor.

Computer System , system architecture

CPU Architecture

The Central Processing Unit ( C P U ) is internally consist of three major units . In other words , the C P U processing functions can be grouped into three units . These units include :

  • Arithmetic Logic Unit ( ALU ) .
  • Control Unit ( CU ).
  • Memory Unit .

Arithmetic Logic Unit ( ALU )

The Arithmetic Logic Unit ( ALU ) of the CPU performs all the arithmetic and logical operations. The ALU performs the desired operation on the data as specified in the program code.

The control unit ( CU ) first decodes the program instructions and directs the ALU to operate on the dats. The ALU then performs the desired operation on the data as per the OP Code ( Operation Code ) decoded by the CU.

What Is CPU ?

computer C P U , Instruction Cycle , Machine Cycle

How CPU Works ?

computer C P U

Control Unit ( CU )

The control Unit ( CU )  Of the processor controls the functioning of  all the internal components and other devices connected to the system.

The control unit also decodes the each program instruction as per the OPCODE and ALU then performs the operation on the OPERAND.

Machine Instruction.

OP Code And Operand

Machine Instruction.

Machine Instruction

CPU Memory Unit

The processor works at very high speed and makes use of high speed internal memory called cpu registers.

The memory unit in a processor consist of high speed memory  that is used by the processor to store the data during the program execution.

CPU And Motherboard Architecture

The motherboard is the main printed circuit board ( PCB ) in a computer system where all the major system components are interconnected.

The   microprocessor chip  is  placed  on  the  motherboard  into the  processor  socket  which firmly holds the processor chip .

The processor socket on the motherboard comes with a liver locking mechanism where the  processor chip is installed.

The CPU works at very high speed that generates considerable heat . And therefore , a heat-sink  is mounted on the top of the processor chip which  protects  the processor chip  from damage due to excessive heat.

Computer System Motherboard

Computer System Motherboard

How CPU Executes Program ?

Machine Cycle

Instruction Cycle

The main function  of the CPU is to  execute the program. The operating system allocates  the  necessary  resources in terms of main memory RAM and the processor time in order to  execute the  program.

The  program code  contains  number  of  program  statements. Each program statement  is an instruction  to the  CPU  to  perform  a  specific  task.

The  C P U  has to repetitively  perform  the   Machine  Cycle ( Instruction Cycle ) which is the basic operation of the CPU.

The machine cycle consist of, four basic operations performed by the CPU. These four instruction cycle operations include : 

CPU Machine Cycle Steps

  • 1. FETCH
  • 2. DECODE
  • 3. EXECUTE
  • 4. STORE

What Is Machine Cycle ?

The machine cycle is  the main activity performed by the central processing unit ( CPU )  to execute the program instruction. The Machine cycle is also alternately referred to as Instruction cycle .

However , the machine cycle is a part of instruction cycle .Whereas, the instruction cycle is the process initiated by the CPU to execute one program instruction .

What Is Machine Cycle ?

CPU Instruction Cycle

Difference Between Instruction Cycle And Machine Cycle

The instruction cycle is the process used by the C P U to execute one instruction. The machine cycle is just a one step of the instruction cycle .

Depending upon the complexity of the program instruction , the processor might need one or more machine cycles to execute one instruction.

The C P U takes  minimum one and  maximum four machine cycle to execute one program instruction. Whereas, one machine cycle takes twelve clock cycles.

Arithmetic Logic Unit , Central Processing Unit , What IS CPU , Instruction Cycle

CPU Functions

The C P U performs some of the most important functions in a computer System and these functions include :

  • To Perform Arithmetic Calculation Operations.
  • To Perform Logical Operations.
  • To Control Functions Of Other Hardware Components.
  • To Fetch the Data And Program Instructions From Main Memory.
  • To Decode the Program Instructions.
  • To Operate On Data As per Program Instructions.
  • To Store Data After Processing.
  • To Continuously Execute Instruction Cycle / Machine Cycle.

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