Group 5 presentation

Roll number • 2051• 2063• 2076• 2082

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The Central Processing Unit:

What Goes On Inside the Computer

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Central Processing Unit

Complex set of electronic circuitry

Executes stored program instructions

Two parts Control unit Arithmetic/logic unit

(ALU)

Addition

Subtraction

Multiplication

Division

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MachineCycle

The time required to retrieve, execute, and store an operation

Components Instruction

time Execution

time

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Computer Processing Speeds

Instruction speeds measured in fractions of seconds Millisecond: one thousandth of a second Microsecond: one millionth of a second Nanosecond: one billionth of a second

• Modern computers have reached this speed

Picosecond: one trillionth of a second

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Data Representation On/Off

Computers understand two things: on and off

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System unit consists of Mother board

Memory slots

Conne

ctor

s –CPU

Chi

ps

PCI expansion slots

ISA expansion slot

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Cpu –a micro processor

Central processing unit etched on silicon chip Size: ½ inch or less

Integrated Circuit (IC) Contain tens of millions of tiny transistors Cpu consists of Expansion Buses/slots Registers Ports and connectors

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Registers

High-speed temporary storage areas Storage locations located within the CPU

Work under direction of control unit Accept, hold, and transfer instructions or

data Keep track of where the next instruction to

be executed or needed data is stored

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Buses

• Parallel electrical paths that transport data between the CPU and memory Expansion System

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Ports

External connectors to plug in peripherals such as printers

Two types of ports Serial: transmit data one bit at a time

• Used for slow devices such as the mouse and keyboard

Parallel: transmit groups of bits together side-by-side

• Used for faster devices such as printers and scanners

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Cache

A temporary storage area Speeds up data transfer within computer Memory cache

• A small block of high-speed memory– Stores most frequently and most recently used data and

instructions– Microprocessor looks in cache first (faster); if not there, it retrieves

from memory

Processor cache• Internal (Level 1) cache built into microprocessor

– Fastest access, but highest cost

• External (Level 2) cache on separate chip• Incorporated into processor on some current microprocessors

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Pipelining

A variation of traditional serial processingFeeds a new instruction into CPU at each

step of the machine cycle

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Questions?

?

? ???

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Sources

Discovering computer 2003 by shelly and

Cashman It series Webopedia

Thank you

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