Understanding Understanding Computer HardwareComputer Hardware

Continued…Continued…

How fast is your computer?How fast is your computer?

Depends on a lot of factorsDepends on a lot of factors– Processor designProcessor design– Clock SpeedClock Speed– Size of Cache memorySize of Cache memory– Bus WidthBus Width– Math-CoprocessorMath-Coprocessor– Graphics processor, Video Processor, Graphics processor, Video Processor,

Audio ProcessorAudio Processor– RAM SizeRAM Size

Continuation of Hardware Lecture…

Operating SystemsOperating Systems

CS101 – Autumn 2006CS101 – Autumn 2006

Operating SystemsOperating Systems

You have already had ample experience You have already had ample experience with at least one of themwith at least one of them– IBM PCs commonly come with IBM PCs commonly come with Windows XP Windows XP

Operating System… Some may have Operating System… Some may have Windows Windows 2000 2000 on themon them

– Macs have Macs have MAC OS MAC OS operating systemoperating system– Sun machines use Sun machines use UNIX UNIX or or LINUX LINUX operating operating

systemssystems– Palm PDAs come with Palm PDAs come with PalmOSPalmOS

Operating systems is how Bill Gates got so Operating systems is how Bill Gates got so rich!rich!

What is an Operating What is an Operating System?System?

An operating system is a ‘program’, a piece An operating system is a ‘program’, a piece of software, rather than hardwareof software, rather than hardware

It is the first program to be loaded in It is the first program to be loaded in memory, after POST is completedmemory, after POST is completed

It is a rather special program – it manages It is a rather special program – it manages the computer and everything that runs on itthe computer and everything that runs on it

Amongst other things, the operating system Amongst other things, the operating system provides you with a provides you with a User-InterfaceUser-Interface, so you , so you can actually use the computercan actually use the computer

More on Operating SystemsMore on Operating Systems A microwave oven has A microwave oven has

a computer in it which a computer in it which manages the keypad, manages the keypad, the display, as well as the display, as well as does computations does computations about cookingabout cooking

Microwave ovens do Microwave ovens do not need an operating not need an operating system, because they system, because they do the same simple do the same simple task over and over task over and over againagain

An oven runs a single An oven runs a single program all the timeprogram all the time

All desktop computers All desktop computers have an operating have an operating systemsystem

The operating system The operating system creates the ability to:creates the ability to:– Serve a variety of Serve a variety of

purposespurposes– Interact with the user in Interact with the user in

more complicated waysmore complicated ways At a simple level, OS At a simple level, OS

does two thingsdoes two things– Manages Manages hardware and hardware and

software software resourcesresources– Provides a way for the Provides a way for the

user to user to deal with deal with hardwarehardware, without , without knowing all its detailsknowing all its details

What does an Operating System What does an Operating System do?do?

Applicationse.g.

MS Word, Calculator

Useri.e.YOU

Operating Systeme.g.

Windows 2000

HardwareCPU, Monitor, Keyboard

You can think of the operating system as a factory manager, who manages resources, inventory, workers and jobs

What does an Operating System What does an Operating System do?do?

The operating The operating system manages a system manages a lot of thingslot of things

IncludingIncluding– MemoryMemory– ProcessorProcessor– Other hardwareOther hardware– ApplicationsApplications– File SystemFile System

Ref: http://computer.howstuffworks.com/operating-system.htm

Types of Operating SystemsTypes of Operating Systems Real-Time Operating Systems (RTOS)Real-Time Operating Systems (RTOS)

– Normally used to control scientific machineryNormally used to control scientific machinery– Ensures that a given task occurs in precisely the time allocated Ensures that a given task occurs in precisely the time allocated

for itfor it– Typically not user friendlyTypically not user friendly

Single-User, Single-TaskSingle-User, Single-Task– At one time, only one task (application, program) can run on At one time, only one task (application, program) can run on

the computerthe computer– Eg. DOS, Palm OSEg. DOS, Palm OS

Single-User, Multi-TaskSingle-User, Multi-Task– Most common type on desktopsMost common type on desktops– E.g. Microsoft Windows, Apple’s MacOSE.g. Microsoft Windows, Apple’s MacOS

Multi-UserMulti-User– Allows several users to work simultaneously on a computerAllows several users to work simultaneously on a computer– Mainly run on serversMainly run on servers– E.g. UNIXE.g. UNIX

Multi-taskingMulti-tasking

PCB – Process Control Block

Useful link to understand more about operating systems…

http://computer.howstuffworks.com/operating-system.htm

Figure Acknowledgement: “How Computers Work” 6Figure Acknowledgement: “How Computers Work” 6thth Ed by Ron White Ed by Ron White (Illustrated by Timothy Edward Downs) © Que Corp 2002(Illustrated by Timothy Edward Downs) © Que Corp 2002

Required Reading: Chapter 4 of textRequired Reading: Chapter 4 of text