What is the Basic Working Principle of Computer?

As Human Beings we can't function properly without our precious organ Brain. 

In the same way Computers can't function without Central Processing Unit also known as CPU which is the Brain of the Computer. 

It transfers information from one part of the computer to another like a Central Switching Station the directs the flow of traffic inside the Computer System. 

Let us see in detail the basic working principle of CPU which is responsible for the successful functioning of the Computer. 

Basic Working Principle of Computer:

The CPU is located on the motherboard of the Computer. Since the CPU carries out a large share of the work in the computer, data continually pass through it. 

The data comes from the RAM and the input units (keyboards, drives, etc.). 

After processing, the data is sent back to the RAM and the output units. 

The CPU continually receives instructions to be executed. 

Each instruction is a data processing order. 

The work itself consists mostly of calculations and data transport. 

Basic Working Principle of Computer (CPU)

The Instruction-Execution Cycle of the CPU: 

Many types of personal computers can execute instructions in less than one-millionth of a second. 

Supercomputers can execute instructions in less than one-billionth of a second. 

The CPU performs four steps in executing an instruction as below 

1.The CU gets the instruction from the memory. 

2.The CU decides what the instruction means and directs the necessary data to be moved from the memory to the ALU. 

Machine (Instruction Execution) Cycle of Computer

3.The ALU performs the actual operation on the data. 

4.The result of the operation is stored in memory or a register. 

The first two instructions make up what is called the instruction time, and the last two instructions make up what is called the execution time. 

The combination of these two is called a machine cycle.

Each CPU has an internal clock (or system clock), which produces pulses at a fixed rate to synchronize all computer operations. 

A single machine cycle instruction is made up of sub instructions, each of which must take at least one clock cycle. 

Each type of CPU is designed to understand a specific group instruction called the instruction set. 

How the CPU finds Instructions and Data:

The location in the memory for each instruction and each piece of data is identified by an address, or a number that stands for a location in the computer memory. 

An address may be compared to a mailbox in everyday life, except that the address can hold only one item – a fixed amount of data, a number or a word – at any one time. 

Control Unit (CU): 

The control unit is a component of a computer's central processing unit (CPU) that directs operation of the processor. 

It controls communication and co-ordination between input/output devices. 

It reads and interprets instructions and determines the sequence for processing the data. 

It is a typical component of the CPU that implements the microprocessor instruction set. 

It extracts instructions from memory and decodes and executes them and sends the necessary signals to the ALU to perform the operation needed. 

Control units are either hardwired (instruction register is hardwired to rest of the microprocessor) or micro-programmed. 

Arithmetic Logic Unit(ALU): 

ALU Concept was proposed by John Von Neumann in 1945 when he was writing a report on the foundations of EDVAC. 

ALU is the fundamental building block of the Central Processing Unit (CPU). 

The simplest microprocessors contain one ALU for purposes such as maintaining timers. Modern computers contain very powerful and complex ALUs and a control unit. 

The ALU performs all arithmetic and logic computations (addition, multiplication, comparison operations like not, and, and or) and almost all the other operations of the Computer is performed by it.