To learn to classify computers according to their capability and
To find out about the essential building blocks that make up a modern
Computer Types According to Capability
4.1 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
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
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
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.
4.7 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
4.8 All computers have the following essential hardware components:
The devices used to give the computer data or commands are called Input
keyboard, mouse, scanner, etc
A processor is the logic circuitry that responds to and processes the
basic instructions that drive a
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
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
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
4.9 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 handheld
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
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
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
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
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-
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
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.
A card on which data can be recorded in the form of punched holes.
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 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
A diskette is a random access, removable data storage medium that can be
used with personal
The term usually refers to the magnetic medium housed in a rigid plastic
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 CDROM
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)
Volatile (RAM), non-volatile (HD)
Direct access (RAM, HD), serial access (Tape)
Read/write (HD, RAM), read-only (CD)
4.15 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
What have we learnt today?
What are the various types of computers with respect to their size,
capability, applications (FIVE
The five essential components of any computer are input devices,
processor, memory, storage and