6. Generations & types of Computer - ( CSI-321)

Chapter No 6: History of Computers
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Chapter No 6
HISTORY OF COMPUTER
Computer word is derived from “Computing”. As the start of the modern science that we call
"Computer Science" can be traced back to a long ago age where man still dwelled in caves or
in the forest, and lived in groups for protection and survival from the harsher elements on the
Earth.
It was a man who decided when to hold both the secret and public religious ceremonies, and
interceded with the spirits on behalf of the tribe. In order to correctly hold the ceremonies to
ensure good harvest in the fall and fertility in the spring, the shamans needed to be able to
count the days or to track the seasons. From the shamanistic tradition, man developed the first
primitive counting mechanisms -- counting notches on sticks or marks on walls.
Computing becoming more and more complicated then the first computing device came in to
being that is Abacus
ABACUS
The first actual calculating mechanism known to us is the abacus, which is thought to have
been invented by the Babylonians sometime between 1,000 BC and 500 BC, although some
pundits are of the opinion that it was actually invented by the Chinese.
The word abacus comes to us by way of Latin as a mutation of the Greek word abax. In turn,
the Greeks may have adopted the Phoenician word abak, meaning "sand", although some
authorities lean toward the Hebrew word abhaq, meaning "dust."

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Irrespective of the source, the original concept referred to a flat stone covered with sand (or
dust) into which numeric symbols were drawn. The first abacus was almost certainly based
on such a stone, with pebbles being placed on lines drawn in the sand. Over time the stone
was replaced by a wooden frame supporting thin sticks, braided hair, or leather thongs, onto
which clay beads or pebbles with holes were threaded.
A variety of different types of abacus were developed, but the most popular became those
based on the bi-quinary system, which utilizes a combination of two bases (base-2 and base-
5) to represent decimal numbers. Although the abacus does not qualify as a mechanical
calculator, it certainly stands proud as one of first mechanical aids to calculation.
JOHN NAPIER CALCULATING DEVICE(1550-1617):
John Napier developed the logarithms rules which are very useful in mathematics and
computer technology. He was a Scottish mathematical scientist. The Logarithm table is
designed by Napier as well which make revolutionary change in mathematics and Computing
Napier's invention led directly to the slide rule, first built in England in 1632 and still in use
in the 1960's by the NASA engineers of the Mercury, Gemini, and Apollo programs which
landed men on the moon. This slide rules is used to take sin, cos, tangent and other
trigonometric & arithmetic calculation.
BLASÉ PASCAL CALCULATING DEVICE(1623-1662):
In 1642 Blasé Pascal, at age 19, invented the Pascaline as an aid for his father who was a tax
collector. Pascal built 50 of this gear-driven one-function calculator (it could only add) but couldn't
sell many because of their exorbitant cost and because they really weren't that accurate (at that time it
was not possible to fabricate gears with the required precision).
Up until the present age when car dashboards went digital, the odometer portion of a car's
speedometer used the very same mechanism as the Pascaline to increment the next wheel after each
full revolution of the prior wheel. Pascal was a child prodigy. At the age of 12, he was discovered
doing his version of Euclid's thirty-second proposition on the kitchen floor. Pascal went on to invent
probability theory, the hydraulic press, and the syringe. Shown below is an 8 digit version of the
Pascaline, and two views of a 6 digit version:

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POLYMATH GOTTFRIED LEIBNIZ CALCULATING
DEVICE (1646-1716):
The great polymath Gottfried Leibniz was one of the first men, who dreamed for a logical
(thinking) device. Even more Leibniz tried to combine principles of arithmetic with the
principles of logic and imagined the computer as something more of a calculator—as a
logical or thinking machine.
He discovered also that computing processes can be done much easier with a binary number
coding. He even describes a calculating machine which works via the binary system: a
machine without wheels or cylinders—just using balls, holes, sticks and canals for the
transport of the balls.

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JOSEPH MARIE JACQUARD CALCULATING DEVICE
(1752-1834):
Joseph Marie Jacquard (1752-1834) was a French silk weaver and inventor, who improved
on the original punched card design of Jacques de Vaucanson's loom of 1745, to invent the
Jacquard loom mechanism in 1804-1805. Jacquard's loom mechanism is controlled by
recorded patterns of holes in a string of cards, and allows, what is now known as, the
Jacquard weaving of intricate patterns.
CHARLES XAVIER CALCULATING DEVICE (1785-1870):
Charles Xavier Thomas de Colmar invented the first calculating machine to be produced in
large numbers. This invention came about in France in 1820 as part of a national competition
and the machine was called the Arithmometer.

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The Arithmometer was essentially an early and large version of a pocket calculator
(occupying the best part of a desk), and by 1845 there was a large, commercially successful
industry involved in the manufacture of these machines.
CHARLES BABBAGE CALCULATING DEVICE (1791-1871):
The first glimmer of a "thinking machine" came in the 1830s when British mathematician
Charles Babbage envisioned what he called the analytical engine. Charles Babbage is s
considered as “Father Of Computing”. Babbage was a highly regarded professor of
mathematics at Cambridge University when he resigned his position to devote all of his
energies to his revolutionary idea.
In Babbage's time, the complex mathematical tables used by ship's captains to navigate the
seas, as well as many other intricate computations, had to be calculated by teams of
mathematicians who were called computers.
No matter how painstaking these human computers were, their tables were often full of
errors. Babbage wanted to create a machine that could automatically calculate a mathematical
chart or table in much less time and with more accuracy.
His mechanical computer, designed with cogs and gears and powered by steam, was capable
of performing multiple tasks by simple reprogramming—or changing the instructions given
to the computer.

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LADY AUGUSTA ADA (1816-1852):
Lady Augusta Ada is mainly known for having written a description of Charles Babbage's
early mechanical general-purpose computer, the analytical engine. Ada was a US
governmental developed programming language. The standard was originally
known as Ada83, but this is now obsolete, as it was recently "overhauled" and
re-born as Ada95. This is now the preferred standard and implementation of the
Ada programming language.
HERMAN HOLLERITH (1860-1929):
Herman Hollerith developed in 1890 the punched card system to store data. The punched
card system was an important movement in the development of the computer. His idea was
totally different from the principle already known by Babbage or by Colmar. He used the
working method of a punch cutter on the train. His calculator was so successful that he
started his own business to sell his product. Later the company was called International
Business Machines (IBM). However the original cards could not be used for complicated
calculations.

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ATANASOFF BERRY COMPUTER:
Atanasoff Berry Computer is the name given, long after the fact, to an experimental
machine for solving systems of simultaneous linear equations, developed in 1938-42 at Iowa
State University by Dr. John Vincent Atanasoff and Clifford E. Berry. It is sometimes
referred to by its initials, ABC.
The Atanasoff-Berry Computer, constructed in the basement of the Physics building at Iowa
State University, took over two years to complete due to lack of funds. The prototype was
first demonstrated in November of 1939. The computer weighed more than seven hundred
pounds (320 kg). It contained approximately 1 mile (1.6 km) of wire.
GEORGE BOOLE INVENTION (1847):
English mathematician George Boole sets up a system called Boolean
algebra,, wherein logical problems are solved like algebraic problems.
Boole's theories will form the bedrock of computer science.
The creation of an algebra of symbolic logic was the work of another mathematical prodigy
and British individualist. . As Bertrand Russell remarked seventy years later, Boole invented
pure mathematics. The design of circuits is arranged by logical statements and these
statements return Zero (0) or one (1). This is called binary language.

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MARK-I, ASCC (1944):
The Harvard Mark I designed primarily by Prof. Howard Aiken launches today's computer
industry. The Mark I is the world's first fully automatic computer and the first machine to
fulfill Babbage's dream. 1945
A programmable, electromechanical calculator designed by professor Howard Aiken. Built
by IBM and installed at Harvard in 1944, it strung 78 adding machines together to perform
three calculations per second. It is also known as ASCC (Automatic Sequence Controlled
Calculator). It was 51 feet long, weighed five tons and used paper tape for input and
typewriters for output. Made of 765,000 parts, it sounded like a thousand knitting needles
The Mark I worked in decimal arithmetic, not binary, but it could go for hours without
intervention.

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ENIAC (1943-1946):
ENIAC stands for Electronic Numerical Integrator and Computer. The first operational
electronic digital computer developed for the U.S. Army by J. Presper Eckert and John
Mauchly at the University of Pennsylvania in Philadelphia. Started in 1943, it took 200,000
man-hours and nearly a half million dollars to complete two years later.
Programmed by plugging in cords and setting thousands of switches, the decimal-based
machine used 18,000 vacuum tubes, weighed 30 tons and took up 1,800 square feet. It cost a
fortune in electricity to run; however, at 5,000 additions per second,
It was faster than anything else. Initially targeted for trajectory calculations, by the time it
was ready to go, World War II had ended. Soon after, it was moved to the army's Aberdeen
Proving Grounds in Maryland where it was put to good work computing thermonuclear
reactions in hydrogen bombs and numerous other problems until it was dismantled in 1955.
ENVAC (1946-1952):
In 1944, while working as a research associate at the Moore School, Dr John Von Neumann
worked on the EDVAC (Electronic Discrete Variable Automatic Computer), greatly
advancing the functions of its predecessor. Completed in 1952, EDVAC had an internal
memory for storing programs, used only 3,600 vacuum tubes, and took up a mere 490 square
feet (45 sq. m).
He undertook a study of computation that demonstrated that a computer could have a simple,
fixed structure, yet be able to execute any kind of computation given properly programmed
control without the need for hardware modification.

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Von Neumann contributed a new understanding of how practical fast computers should be
organized and built; these ideas, often referred to as the stored-program technique, became
fundamental for future generations of high-speed digital computers and were universally
adopted.
EDSAC (1946-1952):
EDSAC stands for Electronic Delay Storage Automatic
Calculator, was an early British computer. The machine,
having been inspired by John von Neumann's seminal
EDVAC report, was constructed by Professor Sir Maurice
Wilkes and his team at the University of Cambridge
Mathematical Laboratory in England.
EDSAC was the world's first practical stored program
electronic computer, although not the first stored program
computer (that honor goes to the Small-Scale Experimental Machine).
The project was supported by J. Lyons & Co. Ltd., a British firm, who were rewarded with
the first commercially applied computer, LEO I, based on the EDSAC design. EDSAC ran its
first programs on May 6, 1949, calculating a table of squares and a list of prime numbers.

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UNIAC-I (1951):
UNIVAC I. First-generation computer was characterized by a very prominent feature on the ENIAC,
vacuum tubes. Until the year 1950, several other computers using these tubes, each computer
provides significant advances in computer development. Development includes arithmetic
binary, random access, and the concept of stored programs.
1951 The U.S. Bureau of Census in 1951 installed the first commercial computer called the
Universal Automatic Computer – UNIVAC I. UNIVAC I developed by Mauchly and Eckert
for the Remington-Rand Corporation.
The first IBM products are sold in the market is the IBM 701 in 1953. Remarkably, the IBM
650 was introduced in the next year that may be the reason IBM is a big benefit in the
previous year. To get rid of its competitors, the IBM 650 was made in order to upgrade the
machine-punched-card machines available. That’s because IBM 650 data processing in a way
similar to the traditional way of punched-card machines.

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GENERATIONS OF COMPUTER
The history of computer development is often referred to in reference to the different
generations of computing devices. A generation refers to the state of improvement in the
product development process. This term is also used in the different advancements of new
computer technology. With each new generation, the circuitry has gotten smaller and more
advanced than the previous generation before it.
As a result of the miniaturization, speed, power, and computer memory has proportionally
increased. New discoveries are constantly being developed that affect the way we live, work
and play.
Each generation of computers is characterized by major technological development that
fundamentally changed the way computers operate, resulting in increasingly smaller, cheaper,
and more powerful and more efficient and reliable devices.
Read about each generation and the developments that led to the current devices that we use
today. The generations which are divided in to fifth categories can be describe as:
Generations Period Technology
Early Period 1000 BC-1940 Many As describe in previous
Chapter
First Generation 1942-1955 Vacuums Tube
Second Generation 1955-1964 Transistors
Third Generation 1964-1975 Integrated Circuits (ICs)
Forth Generation Since 1975 Microprocessor/Large Scale
Integration
Fifth Generation Since 1980 Artificial Intelligence

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THE EARLY DAYS (1,000 B.C. TO 1940)
Computers are named so because they make mathematical computations at fast speeds. As a
result, the history of computing goes back at least 3,000 years ago, when ancient civilizations
were making great strides in arithmetic and mathematics. The Greeks, Egyptians,
Babylonians, Indians, Chinese, and Persians were all interested in logic and numerical
computation. The Greeks focused on geometry and rationality, the Egyptians on simple
addition and subtraction, the Babylonians on multiplication and division, Indians on the base-
10 decimal numbering system and concept of zero, the Chinese on trigonometry, and the
Persians on algorithmic problem solving.
These developments carried over into the more modern centuries, fueling advancements in
areas like astronomy, chemistry, and medicine.
(All other history from abacus to UNIVAC-I describe in previous Chapter)
FIRST GENERATION (1942 - 1955)
The first computers used vacuum tubes for circuitry and magnetic drums for memory, and
were often enormous, taking up entire rooms. First generation computers relied on machine
language to perform operations, and they could only solve one problem at a time.
The Mark-I, EDSAC, EDVAC, UNIVAC-I and ENIAC computers are examples of first-
generation computing devices. It was very expensive to operate and in addition to using a
great deal of electricity, generated a lot of heat, which was often the cause of malfunctions.
Vacuum tubes used to calculate and store information, these computers were also very hard
to maintain. First generation computers also used punched cards to store symbolic
programming languages. Most people were indirectly affected by this first generation of
computing machines and knew little of their existence.

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IMPORTANT MACHINES:
Mark-I, EDSAC, EDVAC, UNIVAC-I and ENIAC
ADVANTAGES:
1. After long history of computations, the 1G computers are able to process any tasks in
milliseconds.
2. The hardware designs are functioned and programmed by machine languages
(Languages close to machine understanding).
3. Vacuum tube technology is very much important which opened the gates of digital
world communication.
DISADVANTAGES:
1. Size of that machines are very big
2. Required large amount of energy for processing
3. Very expensive
4. Heat generated and need air conditioning.
5. Not portable ( never take from one place to other)
6. Comparing with 5G computers, these computers are slow in speed.
7. Not reliable
8. In order to get proper processing, maintenance is required continuously.
SECOND GENERATION (1942 - 1955)
Transistors replaced vacuum tubes and ushered in the second generation computer.
Transistor is a device composed of semiconductor material that amplifies a signal or opens
or closes a circuit. Invented in 1947 at Bell Labs, transistors have become the key ingredient
of all digital circuits, including computers. Today's latest microprocessor contains tens of
millions of microscopic transistors.
Prior to the invention of transistors, digital circuits were composed of vacuum tubes, which
had many disadvantages. They were much larger, required more energy, dissipated more
heat, and were more prone to failures. It's safe to say that without the invention of transistors,
computing as we know it today would not be possible.

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The transistor was invented in 1947 but did not see widespread use in computers until the late
50s. The transistor was far superior to the vacuum tube, allowing computers to become
smaller, faster, cheaper, more energy-efficient and more reliable than their first-generation
predecessors. Though the transistor still generated a great deal of heat that subjected the
computer to damage, it was a vast improvement over the vacuum tube. Second-generation
computers still relied on punched cards for input and printouts for output.
Second-generation computers moved from cryptic binary machine language to symbolic, or
assembly, languages, which allowed programmers to specify instructions in words. High-
level programming languages were also being developed at this time, such as early versions
of COBOL and FORTRAN. These were also the first computers that stored their instructions
in their memory, which moved from a magnetic drum to magnetic core technology. The first
computers of this generation were developed for the atomic energy industry.
IMPORTANT MACHINES:
IBM 7074 series, CDC 164, IBM 1400 Series.
ADVANTAGES:
1. If we compare it with G1 computer, less expensive and smaller in size.
2. Fast in speed
3. Less head generated as G1 computers generate more.
4. Need low power consumption
5. Language after machine language for programming, in G2 assembly language
(COBOL, FORTRON) is introduced for programming.
6. Portable.
DISADVANTAGES:

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1. Maintenance of machine is required.
2. Air conditioning required still as heat causes to process slowly.
3. These computers are not used as personal system.
4. Preferably used for commercial purposes
THIRD GENERATION (1964 - 1975)
The development of the Integrated Circuit was the hallmark of the third generation of
computers. Transistors were miniaturized and placed on silicon chips, called semiconductors,
which drastically increased the speed and efficiency of computers.
Instead of punched cards and printouts, users interacted with third generation computers
through keyboards and monitors and interfaced with an operating system, which allowed the
device to run many different applications at one time with a central program that monitored
the memory. Computers for the first time became accessible to a mass audience because they
were
smaller
and
cheaper
than their
predecesso
rs.
IMPORTANT MACHINES:
IBM System/360 & IBM 370, PDP-8, DEC, UNIVAC 1108, UNIVAC 9000.

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ADVANTAGES:
1. Smaller in size
2. Low cost then previous
3. Low power consumption
4. Easy to operate
5. Portable
6. Input devices introduced and that make user easy to interact with it like keyboard,
mouse etc
7. External Storage medium introduced like floppy & tape.
DISADVANTAGES:
1. IC chips are still difficult to maintain
2. Need complex technology.
FOURTH GENERATION (1975 ONWARDS)
The Microprocessor brought the fourth generation of computers, as thousands of integrated
circuits were built onto a single silicon chip. What in the first generation filled an entire room
could now fit in the palm of the hand.
The Intel 4004 chip, developed in 1971, located all the components of the computer—from
the central processing unit and memory to input/output controls—on a single chip.
In 1981 IBM introduced its first computer for the home user, and in 1984 Apple introduced
the Macintosh. Microprocessors also moved out of the realm of desktop computers
and into many areas of life as more and more everyday products began to use
microprocessors.
As these small computers became more powerful, they could be linked together to form
networks , which eventually led to the development of the Internet. Fourth generation
computers also saw the development of GUIs, the mouse and handheld devices.

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IMPORTANT MACHINES:
Intel processors, AMD processor based machines
ADVANTAGES:
1. Smaller in size
2. High processing speed
3. Very reliable
4. For general purpose
5. More external storage mediums are introduced like CD-ROM, DVD-ROM.
6. GUIs developed for interaction
FIFTTH GENERATION (1980 ONWARDS)
Fifth generation computing devices, based on Artificial Intelligence, are still in
development, though there are some applications, such as voice recognition, that are being
used today.
The use of parallel processing and superconductors is helping to make artificial intelligence a
reality. Quantum computation and molecular and nanotechnology will radically change the
face of computers in years to come.
The goal of fifth-generation computing is to develop devices that respond to natural language
input and are capable of learning and self-organization.

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IMPORTANT MACHINES:
ULAIC Technology, Artificial intelligence etc
PROPERTIES
1. Program independent
2. Have thinking and analysis by its own
3. Voice reorganization & biometric devices
4. Self organization and learning

Chapter No 7: Type of Computer
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Chapter No 7
TYPES OF COMPUTER
The computer sitting on the desk in your classroom is a microcomputer. It is a small,
powerful piece of equipment. Even so, the power of the microcomputer is not enough for
most large organizations. The computer industry consists of more than just microcomputers.
Any classification of computers is somewhat arbitrary. Computer can be classified it to
following basis defined below.
 On the basis of functionality
 On the basis of Size, Speed and Cost.

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ON THE BASIS OF FUNCTIONALITY:
According to functionality computer can be divided in to three types:
1. Analog
2. Digital
3. Hybrid
ANALOG COMPUTERS:
DEFINITION:
 “An analog (spelled analogue in British English) computer is a form of computer that
uses the continuously-changeable aspects of physical fact such as electrical,
mechanical, or hydraulic quantities to model the problem being solved.”
 Analog means continuity of associated quantity just like an analog clock measures
time by means of the distance traveled by the hand of the clock around a dial.
HISTORY:
Mechanical analog computers were very important in gun fire control in World War II and
the Korean War; they were made in significant numbers. In particular, development of
transistors made electronic analog computers practical, and before digital computers had
developed sufficiently, they were commonly used in science and industry.
EXAMPLES:
 Thermometer
 Analog clock
 Speedometer

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 Tire pressure gauge
ADVANTAGES:
 Analog computer has come to refer to
o devices and media that represent
o Store images
o Sound, motion pictures, etc.
DISADVANTAGES:
 Analog computers can have a very wide range of complexity.
 Slide rules and monographs are the simplest, while naval gun fire control computers
and large hybrid digital/analogue computers were among the most complicated.
 Very complicated for containing output for the users some time.
DIGITAL COMPUTERS:
DEFINITION:
 “A computer that performs calculations and logical operations with quantities
represented as digits, usually in the binary number system of “0” and “1”.
 “Computer capable of solving problems by processing information expressed in
discrete form. By manipulating combinations of binary digits (“0”, “1”), it can
perform mathematical calculations, organize and analyze data, control industrial and
other processes, and simulate dynamic systems such as global weather patterns. ”
HISTORY:
In 1937 at Bell Labs, George Stibitz invented the first calculator based on binary circuits to
perform complex mathematical formulas.

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Steinitz’s invention transformed computer science from analog to digital. With the advent of
digital technology, scientists could customize a computer's operating functions by developing
programming languages.
EXAMPLES:
 IBM PC
 Apple Macintosh
 Calculators
 Digital watches etc
HYBRID COMPUTERS:
DEFINITION:
 “A computer that processes both analog and digital data”.
 “Hybrid computer is a digital computer that accepts analog signals, converts them to
digital and processes them in digital form”
A hybrid computer may use or produce analog data or digital data. It accepts a continuously
varying input, which is then converted into a set of discrete values for digital processing.
Examples:
 Hybrid computer is the computer used in hospitals to
measure the heartbeat of the patient.
 Devices used in petrol pump.
 Hybrid Machines are generally used in scientific
applications or in controlling industrial processes.
ON THE BASIS OF SIZE, SPEED AND COST:
We can divide computers on the basis of size cost and speed as:
 Super Computer
 Mainframe Computer
 Mini Computer
 Micro Computer

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 Personal Computer
o Desktop computers
o Laptop /Note Books
 Mobile Computer & Devices
o PDA
o Tablet PC
o Hand Held Computer
o Laptop/Note Books
SUPER COMPUTER
Supercomputers are the largest, fastest, most powerful, and most expensive computers
made. Like other large systems, supercomputers can be accessed by many individuals at the
same time. Supercomputers are used primarily for scientific applications that are
mathematically intensive. The first supercomputer was built in the 1960s for the United
States Department of Defense.
This computer was designed to be the world's fastest and most powerful computer of that
time. The commitment to create the fastest, most powerful computer in the world is still the
driving force behind the development of supercomputers. Manufacturers produce relatively
few of any one model of supercomputer, and they spend millions of dollars on research and
development of new machines.

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Supercomputers derive much of their speed from the use of multiple processors.
Multiprocessing enables the computers to perform tasks simultaneously--either assigning
different tasks to each processing unit or dividing a complex task among several processing
units.
EXAMPLE:
 Cray-1
 Cray-2
 Control Data Cyber 205
 ETA
FEATURES:
 The aerospace, automotive, chemical, electronics and petroleum industries use
supercomputers extensively.
 Supercomputers are used in weather forecasting and seismic analysis. They are found
in many public and private research centers, such as universities and government
laboratories.
 A supercomputer was used to alert scientists to the impending collision of a comet
with Jupiter in 1994, giving them time to prepare to observe and record the event.
 The ultra supercomputer will simulate nuclear explosions (eliminating the need to
detonate any bombs), model global weather trends, and design power plants.
 Supercomputers can perform at up to 128 gigaflops, and use bus widths of 32 or 64
bits. This capability makes supercomputers suitable for processor-intensive
applications, such as graphics.
Note:
The speed of modern supercomputers is measured in nanoseconds and gigaflop. A
nanosecond is one billionth of a second. A gigaflop is one billion floating-point arithmetic
operations per second.

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MAINFRAME COMPUTER
Mainframe computers are the most powerful computers. A mainframe computer may contain
several microprocessors. A single mainframe computer can be used by hundreds of people at
once.
Each user has his own terminal that is connected to the mainframe. Mainframe computers
are usually kept in a special cooled, clean computer room. Minicomputers are medium-sized
computers which are more powerful than microcomputers but not as powerful as mainframes.
A mainframe computer system is usually composed of several computers in addition to the
mainframe, or host processor.
Host Processor:
The host processor is responsible for controlling the other processors, all the peripheral
devices, and the mathematics operations.
Front End processor:
A front-end processor is responsible for handling communications to and from all the remote
terminals connected to the computer system.
Back end Processor:
Sometimes a back-end processor is used to handle data retrieval operations. Although the
host computer could perform all these operations, it can be used more efficiently if relieved
of time-consuming chores that do not require processing speed.

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FEATURES:
 Mainframe computer systems are powerful enough to support several hundred users
simultaneously at remote terminals.
 Mainframe Computers are so much faster than people, the users never notice that the
computer is handling other tasks.
 This capability to process many programs concurrently for multiple users is known as
multiprogramming.
 The typical mainframe computer occupies much of a large room.
 Like supercomputers, mainframes require an environment with closely monitored
humidity and temperature.
 Mainframe computers are priced between $100,000 and $2,000,000.
EXAMPLE:
 IBM S/390
 Amdahl 580
 Control Data Cyber 176
MINI COMPUTER
The "age of the mini" started in the late 1960s. The creation of integrated circuits suitable for
computers enabled designers to shrink the size of the computer. Minicomputers are
frequently referred to as mid-range computers.

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Before Digital Equipment Corporation (DEC) released the first DEC PDP-8 minicomputer
in 1968, most medium-sized organizations were priced out of the computer market because
they couldn't afford mainframe computers.
FEACTURES:
 Like mainframes, most minicomputers are multiuser systems.
 Many of today's minicomputers can accommodate as many as 200 users working
from individual terminals.
 Mini computers are a little slower than mainframe.
 Like mainframes, minicomputers can accommodate remote users, but not as many.
 Minicomputers' input, output, and storage devices look like those on mainframes.
 Minicomputers have slightly less storage, and the printers are slightly slower.
EXAMPLE:
 IBM AS/400
 IBM SYSTEM 360
 HP 3000
 PRIME 9755
MICROCOMPUTER
When you are working on a multiuser computer, such as a mainframe or minicomputer, you
can control the input and see the output on the display, but you control nothing else.
A single-user computer gives you control over all the phases of computer processing: input,
processing, output, and storage. You can select the programs you want to use, and you don't
have to compete with other users to gain access to the system. A single-user system is
designed to meet the computing needs of an individual.
Single-user computers fall into two categories:
 Workstations
 Microcomputers.

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WORKSTATION:
A workstation is a powerful desktop computer designed to meet the computing needs of
engineers, architects, and other professionals who need detailed graphics displays. The
workstation has sometimes been called a "super micro." The workstation looks very much
like a desktop microcomputer, but the chips inside make the difference
For example, workstations are commonly used for computer-aided design (CAD), in which
industrial designers create pictures of technical parts or assemblies. To process these complex
and detailed diagrams, the computer needs great processing power and much storage.
FEATURES:
 Workstations are small, powerful systems designed to drive networks of less powerful
microcomputers and to create high-quality graphics.
 Workstations typically cost $5,000 to $20,000.
 Major competitors in this market include DEC, Hewlett-Packard, Sun, and Silicon
Graphics, Inc.
MICROCOMPUTERS:
It is difficult to overstate the impact of the microcomputer on the computer industry. In 1975,
the microcomputer did not exist. In 1995, sales exceeded $116 billion. Microcomputers are
the fastest growing segment of the computer industry.
The microcomputer segment of the industry is complex; there are different types of
microcomputer platforms with varying capabilities. The most common type of
microcomputer is a desktop computer, which is a non portable personal computer that fits
on top of a desk. (will describe below).
Microcomputers are the smallest and cheapest of these and are used at home, in schools and
in some businesses. Mainframe computers are the most powerful computers

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This table makes some comparisons between the different types of computer:
Comparison Microcomputer Minicomputer Mainframe
Where Used
Home, small
business, on a
network in a
larger business.
Medium sized
business. e.g.
supermarket,
traffic control
system.
Large
businesses,
universities.
Number of
Users
1 1 - 20 Hundreds
Cost
30,000 – 200,000
Rs
25,000-100,00
Rs
Rs
2,000,000+
PERSONAL COMPUTER
DEFINATION:
“A small computer, intended for use by an individual. A personal computer will usually fit on
a desk.”
A computer designed for use by a single user. Although other Microcomputers preceded it,
the IBM PC was the first to use the name specifically. As a result, the term PC now applies to
an IBM-compatible computer as contrasted to the Apple Macintosh, these being the two
standards that emerged from an abundance of competitors in the early 1980s.
PC further divided in to two types:
 Desktop Computer
 Laptop/ Note book Computer
DESKTOP COMPUTER:
DEFINATION:
“A computer designed for desktop use; usually comprises, at a minimum, a central processing
unit (CPU), a monitor, and a keyboard as separate units, connected by special cables. Most
such computers now also include a Pointing Device.

88

A computer that could fit on a desk was considered remarkably small. Desktop computers
come in a variety of types ranging from large vertical tower cases to small form factor models
that can be tucked behind an LCD monitor.
"Desktop" can also indicate a horizontally-oriented computer case usually intended to have
the display screen placed on top to save space on the desktop. Most modern desktop
computers have separate screens and keyboards.
LAPTOP /NOTE BOOK COMPUTER:
DEFINATION:
 “A laptop is a personal computer designed for mobile use, small and light enough to
sit on a person's lap while in use.”
 “A portable computer typically weighing less than 6 pounds (3 kilograms) that has a
flat-panel display and miniature hard disk drives, and is powered by rechargeable
batteries.”
Laptops are capable of many of the same tasks that desktop computers perform, although
they are typically less powerful. Laptops contain components that are similar to those in their
desktop counterparts and perform the same functions but are miniaturized and optimized for
mobile use and efficient power consumption. Laptops usually have LCD displays.
Laptops generally cost around twice as much as a desktop machine of similar specification.
Performance is always lower than that of a comparable desktop because of the compromises
necessary to keep weight and power consumption low.

89

MOBILE COMPUTERS / DEVICES
All devices which can carry in hand and portable, is said to be mobile devices and computers.
These Devices are categorized in:
 PDA
 Tablet PC
 Hand Held Computer
 Laptop/Note Books
PDA
DEFINITION:
PDA stands for “Personal Digital Assistant”. A small, handheld system combining in one
device multiple computing, Internet, networking, and fax/telephone features”A PDA contain
following features:
 Keep phone directories
 Calendars and provide calculator capabilities
 Schedule appointments
 Retrieve frequently used phone numbers
 Jot down notes.
 Most PDAs are designed to accept written input by a pen; the PDA decodes what you
write.

90

TABLET PC
DEFINATION:
 “A tablet PC is a wireless personal computer (PC) that allows a user to take notes
using natural handwriting with a stylus or digital pen on a touch screen.”
A tablet PC is similar in size and thickness to a yellow paper notepad and is intended to
function as the user's primary personal computer as well as a note-taking device.
Tablet PCs generally have two formats, a convertible model with an integrated keyboard and
display that rotates 180 degrees and can be folded down over the keyboard or a slate style,
with a removable keyboard.

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The user's handwritten notes, which can be edited and revised, can also be indexed and
searched or shared via e-mail or cell phone.

HAND HELD COMPUTER
DEFINITION
 “Very small, lightweight device (such as the Palm Pilot) which provides functionality
approaching that of a laptop computer. “
Features of modern handhelds include calendar and diary organizing, word processing, data
management, remote access to firm's network, internet access, wireless access, messaging, etc
LAPTOP/NOTE BOOKS COMPUTER
DEFINATION:

92

 “A laptop is a personal computer designed for mobile use, small and light enough to
sit on a person's lap while in use.”
 “A portable computer typically weighing less than 6 pounds (3 kilograms) that has a
flat-panel display and miniature hard disk drives, and is powered by rechargeable
batteries.”
Laptops are capable of many of the same tasks that desktop computers perform, although
they are typically less powerful. Laptops contain components that are similar to those in their
desktop counterparts and perform the same functions but are miniaturized and optimized for
mobile use and efficient power consumption. Laptops usually have LCD displays.
Laptops generally cost around twice as much as a desktop machine of similar specification.
Performance is always lower than that of a comparable desktop because of the compromises
necessary to keep weight and power consumption low.

6. Generations & types of Computer - ( CSI-321)

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6. Generations & types of Computer - ( CSI-321)