Types of Computers, Components, Parts of Computers

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Introduction to Computing CS101

LESSON 4

Today's Goal

To 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 Capability

4.1 Computer Types According to Capability

4.2 Supercomputers

A supercomputer is a computer that performs at or near the currently highest operational rate for

computers. A supercomputer is typically used for scientific and engineering applications that must

handle very large databases or do a great amount of computation (or both). At any given time, there are

usually a few well-publicized supercomputers that operate at the very latest and always incredible

speeds.

Perhaps the best-known builder of supercomputers has been Cray Research, now a part of Silicon

Graphics. Some supercomputers are at "supercomputer center," usually university research centers,

some of which, in the United States, are interconnected on an Internet backbone (A backbone is a larger

transmission line that carries data gathered from smaller lines that interconnect with it) known as vBNS

or NSFNet.

At the high end of supercomputing are computers like IBM's "Blue Pacific," announced on October 29,

1998. Built in partnership with Lawrence Livermore National Laboratory in California, Blue Pacific is

reported to operated at 3.9 teraflop (trillion floating point operations per second), 15,000 times faster

than the average personal computer. It consists of 5,800 processors containing a total of 2.6 trillion

bytes of memory and interconnected with five miles of cable.

4.3 Mainframe Computers

A very large and expensive computer capable of supporting hundreds, or even thousands, of users

simultaneously. In the hierarchy that starts with a simple microprocessor (in watches, for example) at

the bottom and moves to supercomputers at the top, mainframes are just below supercomputers. In some

ways, mainframes are more powerful than supercomputers because they support more simultaneous

programs. But supercomputers can execute a single program faster than a mainframe. The distinction

between small mainframes and minicomputers is vague (not clearly expressed), depending really on

how the manufacturer wants to market its machines.

4.4 Servers / Minicomputers

A midsized computer. In size and power, minicomputers lie between workstations and mainframes. In

the past decade, the distinction between large minicomputers and small mainframes has blurred,

however, as has the distinction between small minicomputers and workstations. But in general, a

minicomputer is a multiprocessing system capable of supporting from 4 to about 200 users

simultaneously.

4.5 Desktops

These are also called microcomputers. Low-end desktops are called PC's and high-end ones

"Workstations". These are generally consisting of a single processor only, some times 2, along with

MB's of memory, and GB's of storage. PC's are used for running productivity applications, Web

surfing, messaging. Workstations are used for more demanding tasks like low-end 3-D simulations and

Introduction to Computing CS101

other engineering & scientific apps. These are not as reliable and fault-tolerant as servers. Workstations

cost a few thousand dollars; PC around a $1000.

4.6 Portables

Portable computer is a personal computer that is designed to be easily transported and relocated, but is

larger and less convenient to transport than a notebook computer. The earliest PCs designed for easy

transport were called portables. As the size and weight of most portables decreased, they became known

as laptop computer and later as notebook computer. Today, larger transportable computers continue to

be called portable computers. Most of these are special-purpose computers - for example, those for use

in industrial environments where they need to be moved about frequently.

PDA (personal digital assistant) is a term for any small mobile hand-held device that provides

computing and information storage and retrieval capabilities for personal or business use, often for

keeping schedule calendars and address book information handy. The term handheld is a synonym.

Many people use the name of one of the popular PDA products as a generic term. These include

Hewlett-Packard's Palmtop and 3Com's PalmPilot.

Most PDAs have a small keyboard. Some PDAs have an electronically sensitive pad on which

handwriting can be received. Apple's Newton, which has been withdrawn from the market, was the first

widely-sold PDA that accepted handwriting. Typical uses include schedule and address book storage

and retrieval and note-entering. However, many applications have been written for PDAs. Increasingly,

PDAs are combined with telephones and paging systems.

Some PDAs offer a variation of the Microsoft Windows operating system called Windows CE. Other

products have their own or another operating system.

4.7 Ranking w.r.t. installed number

PC's

PDA's

Workstations

Servers

Wearable (picture is provided)

Mainframes

Supercomputers

At the highest level, two things are required for computing

Hardware

Computer equipment such as a CPU, disk drives, CRT, or printer

Software

A computer program, which provides the instructions which enable the computer hardware to work

4.8 All computers have the following essential hardware components:

Input

The devices used to give the computer data or commands are called Input devices. Includes

keyboard, mouse, scanner, etc

Introduction to Computing CS101

Processor

A processor is the logic circuitry that responds to and processes the basic instructions that drive a

computer.

The term processor has generally replaced the term central processing unit (CPU). The processor in a

personal computer or embedded in small devices is often called a microprocessor.

Short for microprocessor, the central processing unit in a computer. The processor is the logic of a

computer and functions comparably to a human central nervous system, directing signals from one

component to another and enabling everything to happen

Memory

Memory is the electronic holding place for instructions and data that your computer's microprocessor

can reach quickly. When your computer is in normal operation, its memory usually contains the main

parts of the operating system and some or all of the application programs and related data that are being

used. Memory is often used as a shorter synonym for random access memory (RAM). This kind of

memory is located on one or more microchips that are physically close to the microprocessor in your

computer. Most desktop and notebook computers sold today include at least 16 megabytes of RAM, and

are upgradeable to include more. The more RAM you have, the less frequently the computer has to

access instructions and data from the more slowly accessed hard disk form of storage.

Memory is also called primary or main memory.

Storage

Computer storage is the holding of data in an electromagnetic form for access by a computer processor.

It is also called secondary storage. In secondary storage data resides on hard disks, tapes, and other

external devices.

Primary storage is much faster to access than secondary storage because of the proximity of the storage

to the processor or because of the nature of the storage devices. On the other hand, secondary storage

can hold much more data than primary storage.

Output

The devices to which the computer

Keyboard Mouse

ControlInteger

writes data are called Output devices.

Unit Unit

Compact

Often converts the data into a human

FloatingCache

Disk

readable form. Monitor and printer are

Point Memory

Unit

output devices.

System Bus

Hard

Processor

Disk

Memory

Bus

Memory

Printer

Monitor

4.9 Input Devices

Mouse

A mouse is a small device that a computer user pushes across a desk surface in order to point to a place

on a display screen and to select one or more actions to take from that position. The mouse first became

a widely-used computer tool when Apple Computer made it a standard part of the Apple Macintosh.

Today, the mouse is an integral part of the graphical user interface (GUI) of any personal computer. The

mouse apparently got its name by being about the same size and color as a toy mouse.

Introduction to Computing CS101

Keyboard

On most computers, a keyboard is the primary text input device. A keyboard on a computer is almost

identical to a keyboard on a typewriter. Computer keyboards will typically have extra keys, however.

Some of these keys (common examples include Control, Alt, and Meta) are meant to be used in

conjunction with other keys just like shift on a regular typewriter. Other keys (common examples

include Insert, Delete, Home, End, Help, function keys, etc.) are meant to be used independently and

often perform editing tasks.

Joystick

In computers, a joystick is a cursor control device used in computer games. The joystick, which got its

name from the control stick used by a pilot to control the ailerons and elevators of an airplane, is a hand-

held lever that pivots on one end and transmits its coordinates to a computer. It often has one or more

push-buttons, called switches, whose position can also be read by the computer.

Digital Camera

A digital camera records and stores photographic images in digital form that can be fed to a computer as

the impressions are recorded or stored in the camera for later loading into a computer or printer.

Currently, Kodak, Canon, and several other companies make digital cameras.

Microphone

A device that converts sound waves into audio signals. These could be used for sound recording as well

as voice chatting through internet.

Scanner

A scanner is a device that captures images from photographic prints, posters, magazine pages, and

similar sources for computer editing and display. Scanners come in hand-held, feed-in, and flatbed types

and for scanning black-and-white only, or color. Very high resolution scanners are used for scanning for

high-resolution printing, but lower resolution scanners are adequate for capturing images for computer

display. Scanners usually come with software, such as Adobe's Photoshop product, that lets you resize

and otherwise modify a captured image

4.10 What is Port?

On computer and telecommunication devices, a port (noun) is generally a specific place for being

physically connected to some other device, usually with a socket and plug of some kind. Typically, a

personal computer is provided with one or more serial ports and usually one parallel port.

4.11Many Types of Ports

Parallel

An interface on a computer that supports transmission of multiple bits at the same time; almost

exclusively used for connecting a printer. On IBM or compatible computers, the parallel port uses a 25-

pin connector.

Introduction to Computing CS101

Serial

It is a general-purpose personal computer communications port in which 1 bit of information is

transferred at a time. In the past, most digital cameras were connected to a computer's serial port in

order to transfer images to the computer. Recently, however, the serial port is being replaced by the

much faster USB port on digital cameras as well as computers.

SCSI

A port that's faster than the serial and parallel ports but slower and harder to configure than the newer

USB port. Also know as the Small Computer System Interface.

A high-speed connection that enables devices, such as hard-disk drives and network adapters, to be

attached to a computer

USB

USB (Universal Serial Bus) is a plug-and-play hardware interface for peripherals such as the keyboard,

mouse, joystick, scanner, printer and modem. USB has a maximum bandwidth of 12 Mbits/sec and up to

127 devices can be attached. With USB, a new device can be added to your computer without having to

add an adapter card. It typically is located at the back of the PC

Firewire

FireWire is simply a really fast port that lets you connect computer peripherals and consumer

electronics to your computer without the need to restart. It is a simple common plug-in serial connector

on the back of your computer.

It has the ability to chain devices together in a number of different ways without terminators for

example, simply join 2 computers with a FireWire cable for instant high-speed networking.

4.12 Processor

Pentium

Celeron

Athlon

PowerPC

StrongARM (PDA)

Crusoe (Laptops)

SPARC (Workstations)

4.13 Memory/Storage

RAM

RAM (random access memory) is the place in a computer where the operating system, application

programs, and data in current use are kept so that they can be quickly reached by the computer's

processor. RAM is much faster to read from and write to than the other kinds of storage in a computer,

the hard disk, floppy disk, and CD-ROM. However, the data in RAM stays there only as long as your

computer is running. When you turn the computer off, RAM loses its data. When you turn your

computer on again, your operating system and other files are once again loaded into RAM, usually from

your hard disk.

Introduction to Computing CS101

Punch cards

A card on which data can be recorded in the form of punched holes.

ROM

ROM is "built-in" computer memory containing data that normally can only be read, not written to.

ROM contains the programming that allows your computer to be "booted up" or regenerated each time

you turn it on. Unlike a computer's random access memory (RAM), the data in ROM is not lost when

the computer power is turned off.

The ROM is sustained by a small long-life battery in your computer.

Hard disk

Hard disk is a computer storage device which saves and retrieves the data when required. Its capacity is

much greater than the computer memory (RAM, ROM). Data on hard disk is stored and retrieved from

electromagnetically charged surface.

Today we can save huge amount of data on a single hard disk. Now hard disks can contain several

billion bytes.

Floppy disk

A diskette is a random access, removable data storage medium that can be used with personal

computers. The term usually refers to the magnetic medium housed in a rigid plastic cartridge

measuring 3.5 inches square and about 2 millimeters thick. Also called a "3.5-inch diskette," it can store

up to 1.44 megabytes (MB) of data.

Tape

In computers, tape is an external storage medium, usually both readable and writable, can store data in

the form of electromagnetic charges that can be read and also erased. A tape drive is the device that

positions, writes from, and reads to the tape.

A compact disc [sometimes spelled disk] (CD) is a small, portable, round medium for electronically

recording, storing, and playing back audio, video, text, and other information in digital form.

DVD

DVD (digital versatile disc) is an optical disc technology that is expected to rapidly replace the CD-

ROM disc (as well as the audio compact disc) over the next few years. The digital versatile disc (DVD)

holds 4.7 gigabyte of information on one of its two sides, or enough for a 133-minute movie.

4.14 Classifying Memory/Storage

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

Introduction to Computing CS101

Volatile (RAM), non-volatile (HD)

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

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

4.15 Output Devices

Printer

Plotter

Speakers

Monitor

4.16 Modem

Modem is output as well as input device at the same time. It receives the data (analog signal) coming

through telephone line, converts them to digital signals and sends them to computer to which it is

attached. It also receives the data from computer and changes it to analog signals.

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

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