higher computingsystems components of a computer system hardware central processing unit (cpu)...

Higher ComputingSystems

Components of a computer systemComponents of a computer system

HardwareHardware

Central Processing Unit (CPU)Central Processing Unit (CPU)

MemoryMemory

Input and Output DevicesInput and Output Devices

SoftwareSoftware

DataData


Components of a computer systemComponents of a computer system

• Computer hardware provides the physical Computer hardware provides the physical mechanisms to store, manipulate and input mechanisms to store, manipulate and input /output data./output data.

• Software provides instructions to tell the Software provides instructions to tell the hardware what tasks to performhardware what tasks to perform

• Data in the computer may be representing Data in the computer may be representing numbers, characters, graphics etc but is numbers, characters, graphics etc but is always kept in a form that the hardware and always kept in a form that the hardware and software can manipulate. software can manipulate.


• CPU performs actual processing of data. CPU performs actual processing of data.

• Data and programs are stored in memory, Data and programs are stored in memory, and moved to and from CPU as required.and moved to and from CPU as required.

• Data travels between system components Data travels between system components along electronic pathways, (sets of wires), along electronic pathways, (sets of wires), called buses.called buses.

Basic concepts - Hardware Basic concepts - Hardware


We will look at: We will look at:

Four Box diagramFour Box diagram CPUCPU MemoryMemory Registers and their roleRegisters and their role Processing speedProcessing speed


Three major components of the Three major components of the CPUCPU: : ALUALU, , Control unit and RegistersControl unit and Registers. .

The The Arithmetic Logic UnitArithmetic Logic Unit (ALU) operates on (ALU) operates on binary data to perform all arithmetic and logical binary data to perform all arithmetic and logical functions. functions.

+ - * / + - * / < > = <> < > = <> AND OR NOT AND OR NOT Rotate ShiftRotate Shift

Control unitControl unit fetches and interprets instructions fetches and interprets instructions in memory and generates signals to control all in memory and generates signals to control all other system components.other system components.


Four Box DiagramFour Box Diagram

Input Output

Backing Store

ProcessorMemory

(RAM and ROM)

CPU


MemoryMemory

Purpose of memory is data storage. A hierarchy Purpose of memory is data storage. A hierarchy of memory exists .of memory exists .

data required for immediate manipulation by data required for immediate manipulation by CPU is stored in small areas of fast access CPU is stored in small areas of fast access memory within CPU calledmemory within CPU called registers registers..

data required for active program is data required for active program is generally stored in primary memory, generally stored in primary memory, commonly called commonly called RAM.RAM.

data which may be required at later time data which may be required at later time generally stored in secondary storage e.g. generally stored in secondary storage e.g. on disk, tape, or CD-Rom.on disk, tape, or CD-Rom.


Memory: characteristicsMemory: characteristics

CapacityCapacity : no of bits, bytes or words in : no of bits, bytes or words in module. Addressable unit - 1 word . Word module. Addressable unit - 1 word . Word size may be 8, 16, 32 bits ; (1 byte = 8 bits)size may be 8, 16, 32 bits ; (1 byte = 8 bits)

Unit of transferUnit of transfer : RAM = 1 word ; Disk = 1 : RAM = 1 word ; Disk = 1 blockblock

access time or speedaccess time or speed - time required to - time required to read from memory location. Tradeoff read from memory location. Tradeoff between quantity, cost and speed . As between quantity, cost and speed . As speed increases so does cost. speed increases so does cost.

Also know as Primary StorageAlso know as Primary Storage


RegistersRegisters: very fast memory internal to CPU : very fast memory internal to CPU providing temporary storage places for data providing temporary storage places for data being manipulated.being manipulated.

System clockSystem clock generates regular pulses to generates regular pulses to synchronize all system events and determine synchronize all system events and determine the speed at which processing can occur. the speed at which processing can occur.

Basic measure of system performance is Basic measure of system performance is clock speed, measured in megahertz (millions clock speed, measured in megahertz (millions of cycles per second) of cycles per second)


Semiconductor main memorySemiconductor main memory

Primary memory is made up of RAM and ROM is made up of RAM and ROM

Types include:Types include: RAM (Random Access Memory)RAM (Random Access Memory) ROM (Read Only Memory)ROM (Read Only Memory)


ROM- SECONDARY STORAGEROM- SECONDARY STORAGE

Read Only MemoryRead Only Memory

• Permanent non-volatilePermanent non-volatile

• Software and data fixed during chip Software and data fixed during chip manufacturemanufacture

• Cannot be written toCannot be written to

• All computers have some ROM to load the All computers have some ROM to load the Operating System into RAM (bootstrap loader) Operating System into RAM (bootstrap loader)


ALU

ControlUnit

CPU

PrimaryMemory

– CPU exchanges data with memory via

the registers such as IR and PC.

RegistersSecondaryMemoryi.e. hard driveCD R/WFloppy

How the components interact

higher computingsystems components of a computer system hardware central processing unit (cpu)...

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