INTRODUCTION TO CPU

Central Processing Unit(CPU) Components of the CPU Actions Performed by CPU CPU REGISTERS MOTHER BOARD CONROL UNIT(CU) ARITHMETIC AND LOGIC UNIT(ALU)

CONTENT

The part of the computer performs the bulk of data processing operations is called the central processing unit.

Central processing unit etched on silicon chip called microprocessor.

Contain tens of millions of tiny transistors.

Central Processing Unit(CPU)

The central processing unit (CPU) of a computer is the main unit that dictates the rest of the computer organization.

Register set: Stores intermediate data during the execution of instructions.

Arithmetic logic unit (ALU): Performs the required micro-operations for executing the instructions.

Control unit: supervises the transfer of information among the registers and instructs the ALU as to which operation to perform by generating control signals.

Components of the CPU

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• Central Processing Unit = “brain”• Executes programs by:

– Fetching and decoding the next instruction from memory

– Execute it• Consists of:

– Control Unit– Arithmetic Logic Unit (ALU)– Registers (high-speed memory)

• Program Counter (PC)• Instruction Register (IR)

Disk PrinterMain

Memory

ControlUnit

Registers

ArithmeticLogic Unit

Bus

• I/O Devices

Actions Performed by CPU

Fetch cycle CPU:• Fetches an instruction from primary storage• Increments a pointer to location of next instruction• Separates instruction into components (instruction code

and data inputs)• Stores each component in a separate register

Execution cycle

ALU:• Retrieves instruction code from a register• Retrieves data inputs from registers• Passes data inputs through internal circuits to perform

data transformation • Stores results in a register

Hold intermediate results and frequently needed data items

Used only by currently executing program Implemented within the CPU, contents can be

read or written quickly Increasing their number usually decreases

program execution time to a point Store information about currently executing

program and about status of CPU

CPU REGISTERS

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Intel and Advanced Micro Devices (AMD) are the two largest manufacturers of CPU’s.

Intel is substantially larger than AMD but they both make CPU’s found commonly in computer systems.

Manufacturers

A motherboard is the physical arrangement in a computer that-

Contains the computer’s basic circuitry and components.

On the typical motherboard, the circuitry is imprinted or affixed to the surface of a firm planar surface and usually manufactured in a single step.

MOTHER BOARD

Control unit controls operations of other parts of CPU as well as all parts of computer by sending a control signal, for example

control sequence of instructions to be executed Control flow of data among all parts of computer Interpret Instructions Regulate timing of processor Send control single to and receive control single

from peripheral devices.

CONROL UNIT(CU)

Arithmetic and logical unit consists of a complicated set of logic circuit and accumulator.

It is mainly responsible for- Calculation Logical comparison and decision

ARITHMETIC AND LOGIC UNIT(ALU)

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