Module3[1] 3rd Class

8/8/2019 Module3[1] 3rd Class

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Module 3Module 3

Introduction To Computer System :

Structure & Processes

Introduction To Computer System :

Structure & Processes


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Module ObjectivesModule Objectives

At the end of the module, students should be able to:

understand the concept and functions of a computer system

identify the component of a computer

identify the components of the central processing unit and

explain how they work together and interact with memory

describe how program instructions are executed by the

computer

explain how data is represented in the computer

understand the concept of bit and byte

identify the types of ports and connectors


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What is A Computer System ?What is A Computer System ?

A functional unit, consisting of one or more

computers and associated software, that uses

common storage for the execution of the

program. Consists of three components

People

Computer programmer

Users/End-user

Software

Hardware


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Functions Of A Computer SystemFunctions Of A Computer System


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Components Of A ComputerComponents Of A Computer

Systems

Interconnection

i.e. bus

CPU

Main

Memory

Input /Output

Communication Lines

PeripheralsComputer


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Complex set of

electronic

circuitry

Executes storedprogram

instructions

Two parts

Control unit

Arithmetic/logic

unit (ALU)

Central Processing UnitCentral Processing Unit

Sends

data to

the CPU

Registers

Control

Unit

ALU

Unit

Processing

InputOutput

Secondary storage

Stores data and programs

Makes

processed

info

available

Central Processing Unit


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Control UnitControl Unit

Directs the computer system to execute

stored program instructions

Must communicate with memory and ALU

Sends data and instructions from

secondary storage to memory as needed


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Arithmetic Logic UnitArithmetic Logic Unit

Executes all arithmetic and logical operations

Arithmetic operations

Addition, subtraction, multiplication, division

Logical operations

Compare numbers, letters, or special characters

Tests for one of three conditions

Equal-to condition

Less-than condition

Greater-than condition


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Intel AdvancedMicro Devices

(AMD)

Cyrix Motorola (Apple)

Pentium IVPentium MMX

Pentium III

Popular CPUsPopular CPUs


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shared communication link

set of wires used to connect multiple subsystems

A Bus is also a fundamental tool for composing

large, complex systems The input/output bus provides a pathway so that themicroprocessor can communicate with input/outputdevices

Systems Interconnection (Bus)Systems Interconnection (Bus)

Control

Data

path

Memory

Processor

Input

Output


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Input / Output BusInput / Output Bus

An input/output bus contains expansionslots which hold expansion cards ISA (Industry Standard Architecture) slotphased out

PCI (Peripheral Component Interconnect) slots

AGP (Accelerated Graphics Port) slot usually forgraphics card

USB (Universal Serial Bus)

PCI Express (PCI-E) latest tech.

PCI slots

Expansion CardAGP slots PCI-E slots


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Data Storage and the CPUData Storage and the CPU

Two types of storage:

Primary storage (memory)

Stores data temporarily / volatile

CPU refers to it for both program

instructions and data Holds input to be processed or holds

results of processing

Secondary storage

Long-term storage / non-volatile

Stored on external medium, such as a disk


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The CPU and MemoryThe CPU and Memory

CPU cannot process data from disk or input device

It must first reside in memory

Control unit retrieves data from disk and moves it into memory

Items sent to ALU for processing

Control unit sends items to ALU, then sends back to memory after

processing

Data and instructions held in memory until sent to an

output or storage device or program is shut down


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Temporary Storage AreasTemporary Storage Areas

High-speed temporary

storage areas

located within the CPU

Work under direction of

control unit

Accept, hold, and transfer

instructions or data

Keep track of where thenext instruction to be

executed or needed data is

stored

Also known as primary

storage / main memory

Often expressed as random-

access memory (RAM)

Not part of the CPU

Holds data and

instructions for processing

Stores information only as

long as the program is in

operation

MemoryRegisters


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The Machine CycleThe Machine Cycle

The time required toretrieve, execute,and store an

operation Components

Instruction time

Execution time System clock

synchronizesoperations


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The Machine CycleThe Machine Cycle

Instruction Time = I-Time Fetch Gets thenext program instruction from the

computers memory

Decode Figures out what the program is telling thecomputer to do

Execution Time= E-Time Execute Performs the requested action

Write-back (Store) Writes (stores) the results to a

register or to memory


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OFFON

0 1

OR = 1 bit

1

0

0 0 001 1

0 0 0 01 1

OR

= 1 Byte

= 1 Byte

OFF

0

0

How Computers Represent DataHow Computers Represent Data

Bit (Binary digit) On or off state of electric current; considered the

basic unit of information; represented by 1s and 0s (binary numbers)

Byte Eight bits grouped together to represent a character (an

alphabetical letter, a number, or a punctuation symbol); 256 different

combinations

ON


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1000 bits = 1 kilobit (kb)

1,000,000bits = 1 megabit (mb)

1,000,000,000 bits = 1 gigabit (gb)

Kilobits per second (Kbps), Megabits persecond (Mbps), and Gigabits per second(Gbps) are terms that describe units of data

used in measuring data transfer rates Example: 56 Kbps modem

BitsBits


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BytesBytes

8 bits = 1 Byte

1024 Bytes = 1 Kilobyte (KB)

1,048,576 Bytes = 1 Megabyte (MB)

1,043,741,824 Bytes = 1 Gigabyte (GB)

1,099,511,627,776 Bytes = 1 Terabyte (TB)

Kilobyte, megabyte, gigabyte, and terabyte are terms

that describe large units of data used in measuring datastorage

Example: 20 GB hard drive

Each byte has 256 (28) possible values


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Kilobyte:1024 (210) bytes Memory capacity of older personal computers

Megabyte: roughly one million (220) bytes

Personal computer memory Portable storage devices (diskette, CD-ROM)

Gigabyte: roughly one billion (230) bytes Storage devices (hard drives)

Mainframe and network server memory

Terabyte: roughly one trillion (240) bytes Storage devices on very large systems

Storage SizesStorage Sizes


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Coding SchemesCoding Schemes

Provide a common way of representing a

character of data

Needed so computers can exchange data

Common Schemes

ASCII

EBCDIC

Unicode


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0 10 0 001 1

= 4

= 4

Representing Characters : Character CodesRepresenting Characters : Character Codes

Character codes translate numerical data intocharacters readable by humans

American Standard Code for Information Interchange

(ASCII) Eight bits equals one character; used by

minicomputers and personal computers

Extended Binary Coded Decimal Interchange Code

(EBCDIC) Eight bits equals one character; used by

mainframe computers

Unicode Sixteen bits equals one character; over 65,000

combinations; used for foreign language symbols

ASCII

0 001 11 1 1

EBCDIC


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Inside the System Unit / CasingInside the System Unit / Casing

Motherboard (mainboard) Largeprinted circuit board with thousandsof electrical circuits

Power supply Transforms

alternating current (AC) from walloutlets to direct current (DC)needed by the computer

Cooling fan Keeps the systemunit cool

Internal Speaker Used for beepswhen errors are encountered

Drive bays Housing for thecomputers hard drive, floppy drive,and CD-ROM / DVD-ROM drives


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Drive bays

On/off switch

Reset button

Indicator lights

FRONT

BACK

The front panel contains drive bays, various buttons, andindicatorlights

Connectors and ports are physical receptacles locatedon the back to connect peripheral devices to the computer

Outside the System UnitOutside the System Unit


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Types of Connectors / PortsTypes of Connectors / Ports

A 15 pin connector

used for monitors

For graphics-intensive

interaction

Data flows through eight wires allowing

the transfer of eight bits of data

simultaneously; faster than serial ports

Allows up to

127 devices

to be

connected at

a time.

keyboard

port -

Special

serial port

to connect

keyboard.

Mouse

portSpecial

serial port

to connect

mouse.

Also called jacks,

sound card connectors

accept stereo mini-

plugs. Microphone,

line-in, line-out, and

speaker connectors

are plugged into thecard.

Serial port Data

flows in a series of

pulses, one after

another one bit at

a time; slow data

transfer rate.


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Other Types of ConnectorsOther Types of Connectors

Small computer system interface (SCSI) port

A parallel interface that enables up to eight

devices to be connected to it

1394 (FireWire) port A high-speed

connection for up to 63 devices

Infrared Data Association (IrDa) port

Infrared signals are used to communicatebetween peripheral devices and the system

unit


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ReferencesReferences

Slides adapted from course materials of

Daley, B. Computers Are Your Future

2006, Complete Ed. Prentice Hall, 2006.

Documents

Module3[1] 3rd Class