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CS101 - Introduction to Computing - Lecture Handout 04

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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

Computer Types According to Capability


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.

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.

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.


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 other engineering & scientific apps.
These are not as reliable and fault-tolerant as servers. Workstations cost a few thousand dollars; PC around a $1000.


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.

Ranking w.r.t. installed number

Wearable (picture is provided)

At the highest level, two things are required for computing


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


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

All computers have the following essential hardware components:


The devices used to give the computer data or commands are called Input devices.
Includes keyboard, mouse, scanner, etc


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 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.


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.


The devices to which the computer writes data are called Output devices. Often converts the data into a human readable form. Monitor and printer are output devices.


Input Devices


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.


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.


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.


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


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

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.

Many Types of Ports


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.


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.


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 (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 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 highspeed networking.


StrongARM (PDA)
Crusoe (Laptops)
SPARC (Workstations)



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.

Punch cards

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

Punch cards


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.


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 (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.

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)

Output Devices



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