Processor ( CPU ) / CPU operations

 

 

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Processor

 

 

 

 

 

Processor

 

: A processor(CPU) is the logic circuitry that responds to and processes the basic instruction that drive a computer. 

** circuit vs circuitry : A circuit is 1 single loop or path of electrical wire. Circuitry is lots of different paths of electrical wire.

 

The CPU is seen as the main integrated circuitry (IC) chip in a computer, as it is responsible for interpreting most of computer's commands. CPU will perform most basic arithmetic, logic and I/O operations, as well as allocate commands for other chips and components running in a computer.

 

The term processor is used interchangeably(교환가능) with the term Central Processing Unit(CPU), although strictly speaking, the CPU is not the only processor in a computer.

 

The GPU (Graphics Processing Unit) is the most notable example, but the hard drive and other devices within a computer also perform some processing independently. Nevertheless,the term processor is generally understood to mena the CPU.

 

Processor can be found in PCs, smartphones, tablets and other computers.

The two main competitors in the processor market are intel and AMD.

 

( https://www.techtarget.com/whatis/definition/processor )

What is processor (CPU)? A definition from WhatIs.com

 

 

 

 

 

The Basic elements of processor

 

The basic elements of processor include:

 

- the Arithmetic Logic Unit (ALU), which carries out arithmetic and logic operations on the operands in instructions.

 

- the Floating Point Unit (FPU), also known as a math coprocessor or numeric coprocessor, a specialized coprocessor that manipulates numbers more quickly than the basic microprocessor circuitry can.

 

(** coprocessor : 보조프로세서로서, 주 CPU 프로세서에 집중된 작업들의 짐을 덜어 시스템 수행 속도를 빠르게 해 준다. )

 

-  Registers, which hold instructions and other data. Resgisters supply operands to the ALU and store the results of operations.

 

- L1 and L2 cache memory. Their inclusion in the CPU saves time compared to having to get data from random access memroy (RAM)

(** cache(캐시) : 자주 사용하는 data나 값을 미리 복사해놓는 임시 장소) //https://mangkyu.tistory.com/69

 

 

 

 

 

CPU operations

 

The four primary functions of a processor are fetch, decode, execute and write back.

 

- Fetch is the operation which receives instructions from program memory.

- Decode is where the instruction is converted to understand which other parts of the cpu are nedded to continue the operation. This is performed by instruction decoder.

- Execute is the where the operation is performed. Each part of the cpu that is needed is activated to carry out th instruction,

 

실행할 명령어의 주소는 Program counter에 저장되어 있다. 따라서 program counter에 저장되어 있는 주소로 가서 instruction을 읽어, instruction registor(IR)에 저장한다. 그리고 program counter의 값을 증가시킨다.

decode는 0과 1로 이루어진 instruction을 해석하는 과정이다. 디코딩은 인코딩 하기 전으로 정보를 되돌리는 과정으로 위의 과정에서는 3bit으로 이루어진 binary code를 2의 n승개의 정보로 바꿔주는 논리회로이다.이는 다수의 입력신호로 하나의 출력값을 얻으므로 일종의 mux라고 할 수 있다.

이 과정을 통해 제어장치가 무슨 명령어를 실행해야 하는 지 결정하게 된다. 이 때 각 기계마다 instruction set이 다르므로 컴퓨터는 오직 그 장치의 언어로 표현된 명령어만 실행이 가능하다.