CS101 Introduction to ComputingLecture 4Computer Systems

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 transistor based, and how the future belongs to quantum computers

We discussed how the size is drastically decreasing with time and how their capability is increasing year by year

Todays GoalTo learn to classify computers according to their capability and targeted applications

To find out about the essential building blocks that make up a modern computer

Computer Types According to CapabilitySupercomputers

Mainframes

Servers

Desktops

Portables

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-scale problems: 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 focus all their resources and capabilities on a single task at a time

Supercomputers (2)Early supercomputers used a single or a few processors working in parallel

Those processors were custom-built for the supercomputers, and were, therefore, very expensive

Modern supercomputers use the same processors that are used in desktop PCs. They, however, are designed to use 1000s of them working together in parallel

Why use many not-so-powerful processors working in parallelWhy not just design a single, really powerful processor

Post your answers on the CS101 message board ??

The Champion: ASCI WhiteMost powerful computer as of February 2002

Capable of 12.3 trillion calculations/sec74,000 times faster than Cray 1 (1976)1,000 times faster than Deep Blue (1997)

Designed for complex 3-D simulations required for testing nuclear weapons

Powered by 8192 microprocessors

6 TB of memory; 160 TB of storage capacity

Mainframe Computers (1)Also called Enterprise Servers

Designed for performing multiple, intensive tasks for multiple users simultaneously

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

Mainframe Computers (2)Designed for very-high reliability

Can be serviced/upgraded while in operation

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

Cost in millions of dollars

Servers/Minicomputers (1)The name minicomputers used to define the class of computers that lies between personal computers and mainframes

Then very high-end desktop computers called low-end or mid-range servers took over the role that was previously played by minicomputers

Servers/Minicomputers (2)Low-end and mid-range servers are used by small businesses and organizations as file-stores, to run e-mail systems and Web sites

Generally are more reliable than desktops, but not as solid as the mainframes

Generally consist of 2 or more processors, GBs of memory, and TBs of storage

Costs in hundreds of thousands of dollars

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, and GBs of storage

Desktop Computers (2)PCs are used for running productivity applications, 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

Mobile Computers (1)Laptops, palmtops, and wearable computers are very capable computers but are light-weight and consume very little power

Laptops (also called notebook computers) generally weigh around 2kg, use special low-power processors, typically have 256MB memory, 40GB of storage, can work for more than 2 hours on battery

Their usage is similar to that of PCs

They cost in the range of $1500-2500

Mobile Computers (2)Palmtops, also known as PDAs - Personal Digital Assistants

Weigh less than a pound, have very low-power processors, KBs of memory, MBs of storage capacity

Can run for many hours on AA batteries

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

Palmtops cost $200-600

Mobile Computers (3)Wearables are small in size, carried in a pocket, worn on the arm, waist, or head or elsewhere on 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 doing other activities

Each soldier of the future will be fitted with one

Click here to view the picture of a wearable computer

Ranking w.r.t. installed numberPCsPDAsWorkstationsServersWearables (will take the top spot in future)MainframesSupercomputers

Now that we have learnt about the various types of computers and about their typical applications, lets move on to a new topic

Lets now find out about the essential components that are present in every type of computers

At the highest level, two things are required for computingHardware: The physical equipment in a computing environment such as the computer and its peripheral devices (printers, speakers, etc.)

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

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

However, for the rest of todays discussion, lets concentrate on hardware

All computers have the following essential hardware components:Input the component through which a user instructs a computer about what to do

Processor the engine that processes the instructions given by the user

Memory where the processor stores information that is required during its computations

Storage where information that is required to be used much later is stored

Output the component that communicates the results of a computation to the user

There is another quite essential component that is present in every computer

????

The Bus!

KeyboardMousePrinterMemoryHardDiskMemoryBusSystem BusMonitorCompactDiskProcessorIntegerUnitControlUnitCacheMemoryFloatingPointUnit

Input DevicesMouseKeyboardJoystickCameraMicrophoneScanner

Whats a Port?

PortThe connection point at which we connect input and output devices to a computer

Many Types of PortsParallelSerialSCSIUSBFirewire

ProcessorPentiumCeleronAthlonPowerPCStrongARM (PDA)Crusoe (Laptops)SPARC (Workstations)

Memory/StorageRAM Punch cardsROMHard diskFloppy diskTapeCDDVD

Classifying Memory/StorageElectronic (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)

Output DevicesPrinter

Plotter

Speakers

Monitor

modeminput device or output device?

modem

modulatordemodulatoromdemmodem

Modem is an example of a device that acts both as an input as well as an output deviceCan you think of any other such dual-purpose devices?

Network caredTouch screens

What have we learnt today?

What are the various types of computers with respect to their size, capability, applications (FIVE TYPES)

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

Next time well find out aboutWhat are the major building blocks of a modern personal computer?

How those building blocks are put together to form a PC?