Wednesday, August 29, 2012

What is central processing unit (CPU) how it is work

The CPU is the brain of a computer system. All major calculations and comparisons performed by a computer are carried out inside its CPU.
 The CPU is also responsible for activating and controlling the operation of other units of the computer system. Hence, no other single component of a computer determines its overall performance ,as much as the CPU, In order to be able to quickly evaluate any computer capabilities it is important to know how CPU are internally structured how different CPUs differ from each other ,and how CPU speed is evaluated. These and other related concepts about CPU are described below.

The Control Unit.



We saw that the two basic components of a CPU are the control unit and the arithmetic logic unit. The control unit of the CPU selects and interprets program instructions, and then sees that they are executed. It has some special purpose registers (whose functions are described in a latter subsection), and a decoder to perform these activities. The special purpose registers, namely the Instructions register and the program control register, respectively hold the current instruction and the next instruction to be executed, and in this way help the control unit in instruction selection. On the other hand. The decoder has the necessary circuitry to decode and interpret the meaning of every instruction supported by the CPU. Each instruction is accompanied by microcode—very basic directions. Which tell the CPU how to execute the instruction?
Although, the control unit does not perform any actual processing of the data, it acts as a central nervous system for other components of the computer. It manages and coordinates the entire computer system, including the input and output units. It obtains instructions from the program stored in the main memory, interprets the instructions, and issues signal, which cause other units of the system to execute them.

The Arithmetic Logic Unit (ALU)



The ALU of the CPU is the place, where the actual execution of the instructions takes place, during the data procession operation. That is, when the control unit encounters an instruction, which involves an arithmetic operation (such as, add, subtract, multiply, divide), or a logic operation (such as less than, equal to, greater that), it passes control to the ALU. The ALU has some special purpose registers and the necessary circuitry, to carry out all the arithmetic and logic operations, which are included in the instructions supported by the CPU. For example, the arithmetic and logic operations, which are included in the instructions supported by the CPU.For example, the control unit might load two numbers into the registers in the ALU.Then, it might the ALU to add the two numbers (an arithmetic operations), or to check if the two numbers are equal (a logical operation).

In case of a microcomputer, the entire CPU (both the control unit and the ALU) is contained on a single tiny silicon chip, called a microprocessor.

1 comment:

  1. Unit in instruction selection. On the other hand. The decoder has the necessary circuitry to decode and interpret the meaning of every instruction supported by the CPU. Each instruction is accompany by microcodeery basic directions. Which tell the CPU how to execute the teaching.

    Windows Wakefield


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