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CS101 Introduction to Computing

Lecture 4Computer Systems

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During the Second Lecture

We talked about the evolution of computers

How initial computers were mechanical, and

then came electro-mechanicals, then tube-based, and finally transistorbased, and howthe future belongs to quantum computers

We discussed how the size is drasticallydecreasing with time and how theircapabilityis increasing year by year

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Todays Goal

1. To learn to classifycomputers accordingto theircapability and targetedapplications

2. To find out about the essential buildingblocks that make up a modern computer

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Computer Types According to Capability

Supercomputers

Mainframes

Servers

Desktops

Portables

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Supercomputers (1)

State-of-the-art machines designed to perform

calculations as fast as the current technology allows

Used to solve extremely complex and large-scaleproblems: weather prediction, simulation of atomic

explosions; aircraft design; movie animation

Cost tens of millions of dollars

Unique in that unlike mainframes &personal computers, designed to focusall their resources and capabilities on a

single task at a time

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Supercomputers (2)

Early supercomputers used a single or a fewprocessors working in parallel

Those processors were custom-built for the

supercomputers, and were, therefore, veryexpensive

Modern supercomputers use the sameprocessors that are used in desktop PCs.They, however, are designed to use 1000s

of them working together in parallel

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Why use many not-so-

powerful processorsworking in parallel

Why not just design a

single, really powerfulprocessor

Post your answers on the CS101 message board

?

?

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The Champion:ASCI White

Most powerful computer as of February 2002

Capable of12.3 trillion calculations/sec 74,000 times faster than Cray 1 (1976)

1,000 times faster than Deep Blue (1997)

Designed forcomplex 3-D simulationsrequired for testing nuclear weapons

Powered by 8192 microprocessors

6 TB of memory; 160 TB of storage capacity

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Mainframe Computers (1)

Also called Enterprise Servers

Designed for performing multiple, intensive

tasks formultiple users simultaneously

Used by large businesses (e.g. banks, e-commerce sites), military, and industrial

organizations

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Mainframe Computers (2)

Designed forvery-high reliability

Can be serviced/upgraded while in operation

Generally consist ofmultiple processors,GBs of memory, and TBs of storage

Cost in millions of dollars

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Servers/Minicomputers (1)

The name minicomputers used to definethe class of computers that lies betweenpersonal computers and mainframes

Then very high-end desktop computers called low-end or mid-range servers

took over the role that was previouslyplayed by minicomputers

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Servers/Minicomputers (2)

Low-end and mid-range servers are used bysmall businesses and organizations as file-stores, to run e-mail systems and Web sites

Generally are more reliable than desktops, butnot as solid as the mainframes

Generally consist of2 or more processors,

GBs of memory, and TBs of storage

Costs in hundreds of thousands of dollars

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Desktop Computers (1)

Also called microcomputers

Low-end desktops are called PCs and high-end

ones Workstations

Generally consist of a single processor only,

some times 2, along with MBs of memory, andGBs of storage

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Desktop Computers (2)

PCs are used for running productivityapplications, Web surfing, messaging

Workstations for more demanding tasks like

low-end 3-D simulations and other engineering& scientific apps

Are not as reliable and fault-tolerant as servers

Workstations cost a few thousand dollars; PC

around a $1000

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Mobile Computers (1)

Laptops, palmtops, and wearable computers arevery capable computers but are light-weight andconsume very little power

Laptops (also called notebook computers) generallyweigh around 2kg, use special low-powerprocessors, typically have 256MB memory, 40GB ofstorage, can work for more than 2 hours on battery

Theirusage is similar to that of PCs

They cost in the range of $1500-2500

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Mobile Computers (2)

Palmtops, also known as PDAs - Personal DigitalAssistants

Weigh less than a pound, have very low-power

processors, KBs of memory, MBs of storage capacity

Can run for many hours onAA batteries

Used as an electronic version of a pocket diary. Alsofor Web surfing and e-mail or even as mobile phones

Palmtops cost $200-600

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Mobile Computers (3)

Wearables are small in size, carried in a pocket,worn on the arm, waist, or head or elsewhereon the body

Capability similar to PDAs, but more expensive

They are always ON, and always accessible.That is, the user can always enter and execute

commands, even while walking around or doingother activities

Each soldier of the future will be fitted with one

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Click here to view the picture

of a wearable computer

http://localhost/var/www/apps/conversion/tmp/scratch_2/wearable%20computerhttp://localhost/var/www/apps/conversion/tmp/scratch_2/wearable%20computerhttp://localhost/var/www/apps/conversion/tmp/scratch_2/wearable%20computerhttp://localhost/var/www/apps/conversion/tmp/scratch_2/wearable%20computer

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Ranking w.r.t. installed number

PCs

PDAs

Workstations

Servers

Wearables (will take the top spot in future)

Mainframes Supercomputers

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Now that we have learnt about the varioustypes of computers and about theirtypical

applications, lets move on to a new topic

Lets now find out about the essential

components that are present in every typeof computers

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At the highest level, two thingsare required for computing

Hardware: The physical equipment in acomputing environment such as the

computer and its peripheral devices(printers, speakers, etc.)

Software: The set of instructions thatoperates various parts of the hardware.Also termed as computer program

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Well have a lot to say about softwareduring the duration of this course

However, for the rest of todays

discussion, lets concentrate on hardware

All t h th f ll i

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All computers have the followingessential hardware components:

Input the component through which a userinstructs acomputer about what to do

Processor the engine that processes the instructions

given by the user

Memory where the processor stores information that isrequired during its computations

Storage where information that is required to be usedmuch lateris stored

Output the component that communicates the results

of a computation to the user

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There is another quite essential componentthat is present in every computer

????

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The Bus!

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Keyboard Mouse

PrinterMemory

HardDisk

Memory

Bus

System Bus

Monitor

CompactDisk

Processor

IntegerUnit

ControlUnit

CacheMemory

FloatingPointUnit

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Input Devices

Mouse Keyboard

Joystick

Camera Microphone

Scanner

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Whats a

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Port

The connection point at which we connectinput and output devices to a computer

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Many Types of Ports

1. Parallel2. Serial

3. SCSI

4. USB

5. Firewire

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Processor

Pentium Celeron

Athlon

PowerPC StrongARM (PDA)

Crusoe (Laptops)

SPARC (Workstations)

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Memory/Storage

RAM Punch cards

ROM

Hard disk Floppy disk

Tape

CD

DVD

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Classifying Memory/Storage

Electronic (RAM, ROM)magnetic (HD, FD, Tape),optical (CD, DVD)

Volatile (RAM), non-volatile (HD)

Direct access (RAM, HD), serial access (Tape)

Read/write (HD, RAM), read-only (CD)

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Output Devices

Printer

Plotter

Speakers

Monitor

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input device or output device?

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modem

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modulatordemodulatorom d e m

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Modem is an example of a devicethat acts both as an input as well

as an output device

Can you think of any other such dual-purpose devices?

Network cared

Touch screens

Wh t h l t t d ?

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What have we learnt today?

What are the various types of computerswith respect to theirsize, capability,applications (FIVE TYPES)

The five essential components of anycomputer are input devices, processor,memory, storage and output devices

N t ti ll fi d t b t

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Next time well find out about

1. What are the major building blocksof a modern personal computer?

2. How those building blocks are puttogether to form a PC?