Processing Unit/CPU

Central Processing Unit (CPU) :

Introduction

• • The task of performing operations like arithmetic, logical and non-logical/arithmetic operations is called Processing.
  • The CPU is a complex IC chip having millions of transistors.
  • The CPU or central processing unit takes data and instructions from the storage/ memory unit and makes all sorts of calculations based on the instructions given and the type of data provided. It is then sent back to the storage unit to store it.
  • In order to carry out the operations, the computer allocates the task among its various operational units i.e. arithmetic logical unit, control unit, and register.
  • The term CPU relates to a specific chip or the processor.
  • Central Processing Unit (CPU) is considered as one of the most important component of a computer system.
  • The Central Processing Unit (CPU) is like the brain of the computer. This is because it takes all major decisions, makes all sorts of calculations and directs different parts of the computer functions by activating and controlling the operations.
  • The fundamental operation of most CPU is to execute a series of instructions called as a program.
  • The main function of a CPU is to execute a series of instructions called as program in a specific sequence. Normally there are four steps that all CPU use in order to perform their operation these are: fetch, decode, execute and output.
  • A dual-core processors has two cores, a quad-core processor contains four cores and a hexa-core processor contains six cores on a single chip. Multi-core processors implement multi-processing which improves performance and speed of executions.
  • The different chip manufacturers use different measuring standards to measure the processor’s speed. It depends on the circuit board that the chip is housed in, or the motherboard. 
  • It is responsible for executing instructions.
  • It controls and coordinates the execution of instructions.
  • Execution of an instruction involves almost all parts (CU, ALU & Registers) of the CPU. Hence, CPU is known as the most vital component of a computer system. 
  • CPU mainly involves in processing of input data. Processing the data thus means manipulation of letters, numbers and symbols in a specific manner. The processing may include calculations, decision making, comparisons, classification, sorting, aligning & formatting etc. The processing of data results in some meaningful values/output, often termed as ‘information’.
  • As we know that, computer takes the raw data as input and performs several operations on these data in order to produce the desired output by the CPU so it acts as a processing unit for those data.
  • The CPU chip is connected with other components of the computer through a system bus (printed wires on the mother board) which has three sets of wires forming Control Bus, Data Bus and Address Bus.

Features

• CPU is considered as Brain of the computer.
• A CPU in a computer system is an extremely fast device as compared to the main memory, but it can not work on its own. It depends on the main memory to receive data and instruction when required for processing.

Function

• The central processing unit performs the bulk of the data processing operations i.e. CPU regulates the functioning of entire operations of processor and memory along with input and output devices.
• In another words, it controls the activities of almost all functioning parts of the computer.

Components/Structure of CPU

• • The Processor is made up of the registers, arithmetic & logic unit and control units.
  • A CPU typically comprised of Processor and Memory Unit i.e. (A) Control Unit (CU), (B) Arithmetic & Logic Unit (ALU) (C) Set of Registers (D) Memory Unit(MU) 

(A)Control Unit (CU) – 

Click this link to go Control Unit details

(B)Arithmetic & Logic Unit (ALU)

• • This is the major components of CPU.
  • The ALU is responsible for performing arithmetic as well as logical operations on data/signal as per given instructions. The CU, CPU registers and memory help in bringing the data into the ALU and then taking the results back.
  • Data are presented to ALU in registers and the results are also stored in registers. Accumulator is one such register which is very frequently used during the ALU operation.
  • ALU has many other registers such as flags and status register, which indicate information about the operation and its result.
  • ALU has logic implemented to perform operations like addition, multiplication, division, shifting, complement etc. The operations are performed on represented numbers, both integer and floating point numbers.
  • Modern processors work through two ways which improve ALU performance to a much higher level. These are use of on chip Cache memory and having more than one processor core on the same IC chip. Here, Cache memory is a fast semiconductor memory which can be used to temporarily store instructions and data that are frequently referred by the processor thus, the wait cycles introduced due to memory references are minimized and hence the processor performance improves a lot. Another modern technique of having use of more than one processor core on the same IC chip tries to perform the execution of instructions in parallel and hence the performance of the processor improves a lot.
  • The co-processor or the arithmetic-logic unit does arithmetic, non-arithmetic and logical operations.
  • The Arithmetic Logical Unit is an important component of the CPU, which carry the actual execution of the instructions.
  • The brief working mechanism of ALU is – After entering the data through the input device it is stored in the primary storage unit/RAM. Then processing of the data and instruction are performed by Arithmetic Logical Unit. After that output is sent to the monitor screen to display or printer to print on paper as hard copy or hard disk to store it permanently via main memory or RAM.
  • The major operations performed by the ALU during processing are addition, subtraction, multiplication, division, logic and comparison.
  • Data is transferred to ALU from storage unit when required. After processing, the output is returned to the storage unit for further processing or getting stored.

(C)Registers/CPU Registers/Processor Memory

(For More Registers memory Details, Click this Link)

(D)Memory Unit(MU)

(For More Memory Unit Details, Click this Link)