Computer Hardware

Computers and components

Basic Computer System

MAIN MEMORY

ALU CNTL.....

BUS

CONTROLLER

Processor

I/O moduleInterconnections

BUS

ATTACHEDDEVICE

ComputerComponents

CPU Cycle

Start FETCH EXECUTE Halt

Increment Program Counter

FETCH EXECUTE

Execution Cycle

Instruction SetsComplex (CISC) or Reduced (RISC)

ALUCNTL

.....

ROM

INSTRUCTIONS

Measuring Processing Power

Clock SpeedInstruction SpeedWord Length and Bus WidthSpeed of ArithmeticInstruction SetPipelining

Primary Storage

Volatile DRAM SRAM Cache

Nonvolatile ROM

Kilobytes KB 1,000 BText document

Megabytes MB 1,000,KBImages

Gigabytes GB 1,000 MBHard disk drives

Terabytes TB TrillionsData warehouse files

Measuring Storage (bytes)

Attached I/O Devices

Secondary Storage DASD Tape Removable

Electronic Storage

Optical (etc.) devices

Communication Devices Modems and

Codecs LAN’s, Backbones

and WAN’s Routers and

other node devices

Secondary Storage Devices

Fixed Mediahard disksRAID

Removable Mediadiskettelaser-servo

diskettecartridge diskstapeCD-ROMflash memory

Attached Devices

Hardware: device itself such as a disk or video display device.

Electronics: controller that communicates with the device

Software: device driver that is loaded into the computer operating system

Local and Peripheral

Bus

Data Transfer:

MAIN MEMORY

BUFFER

CPU

T AAD

CONTROLLER

DASD

CPUCPUCPUCPU

CHANNEL

I/O Controller (DASD)

PROCESSOR REGISTER

REGISTER

REGISTER

BUFFER

Direct Access Storage Device (DASD)

DASD Structure

Read-Write Heads

Cylinder/Track/Block

Block (Sector)Track

Cylinder

Disk Organization

Data Storage

FAT (File Access Tables), Directories and Catalogs

Update and DeleteFragmentation and reorganizationBlocks, Headers and Interblock Gaps

Hardware II

General Purpose Computing

Software primacyApplications are controlled by changing the instructions run by the computer, rather than by changing the hardware

ASIC’s and FirmwareAny program that can be written in software can also be burned onto a chip as a family of circuits

Computer Classifications

Size mainframe midrange microcompute

r

Function legacy

mainframe server router client

Mainframe (Legacy)

Tuned for transaction processing

Has channels to support very large numbers of attached devices

Runs a mainframe operating system

Tend to support legacy software

Client/Server Architectures

SERVER PROCESSING

CLIENT PROCESSING

CENTRALIZED STAND-ALONE

FAT SERVER FAT CLIENT

Client/Server Architecture

An architecture in which the client (personal computer or workstation) is the requesting machine and the server is the supplying machine, both of which are connected via a network.

Client/Server Architecture

ClientMay do some or all

of the processingRequests services

from the network

ServerContains data and

may contain programs

Server downloads information (applications or data) to the client for operation

Client

Use relatively inexpensive computer chips (Intel or Motorola)

Have a single processorOptimized for user

convenienceSingle userLimited numbers of

attached devices

Server

Use inexpensive CPU chips

Designed with redundant components

Have large internal memory capacity

May not need very fast CPU capability

Three Tier Client/Server

Any time Any place Any way

Router

Used to segment networks and prepare message packets for transmission

Special purpose operating system to read and forward message packets

May support firewall functionsSupport special purpose CPU chips

and optimized network sysems

Routers

Input Buffer

Proces- sor

Output Buffer

From A From B

To C To D

Table ofAddresses

Input Buffer

Input BufferOutput Buffer

Central ArchitectureClient/ServerWeb Access