GENERATIONS OF COMPUTER
"Generation" in computer talk is a step in
technology. It provides a framework for the growth of the computer industry.
The custom of referring to the computer era in terms of generations came into
wide use only after 1964. There are totally five computer generations known
till today. Although there is a certain amount of overlapping between the
generations, the approximate dates shown against each are normally accepted.
FIRST GENERATION (1942 - 1955)
We have already discussed
about some of the early computer - ENIAC, EDVAC, EDSAC, etc. These machines and
other of their time were made possible by the invention of "vacuum
tube", which could control and amplify electronic signals. These vacuum
tube computers are referred to as first-generation computers.
Advantages
1.
Vacuum tubes were the
only electronic components available during those days.
2.
Vacuum tube technology
made possible the advent of electronic digital computers.
3.
These computers were the
fastest calculating devices of their time. They could perform computations in
milliseconds.
Disadvantages
1.
Too bulky in size.
2.
Unreliable.
3.
Thousands of vacuum
tubes that were used emitted large amount of heat and burnt out frequently
4.
Air conditioning
required.
5.
Prone to frequent
hardware failures.
6.
Constant maintenance
required.
7.
No portable.
8.
Manual assembly of
individual components into functioning unit required.
9.
Commercial production
was difficult and costly.
10.
Limited commercial use.
SECOND GENERATION (1955 - 1964)
The transistor, a smaller
and more reliable successor to the vacuum tube, was invented in 1947. However,
computers that used were not produced in quantity until over a decade later.
The second generation emerged with transistors being the brain of the computer.
With both the first and
the second-generation computers, the basic component was a discrete or separate
entity. The manual assembly of individual components and the cost of labor
involved at this assembly stage made the commercial production of these
computers difficult and costly.
Advantages
1.
Smaller in size as
compared to first generation computers.
2.
More reliable.
3.
Less heat generated.
4.
These computers were
able to reduce computational times from milliseconds to microseconds.
5.
Less prone to hardware
failures.
6.
Better portability.
7.
Wider commercial use.
Disadvantages
1.
Air-conditioning
required.
2.
Frequent maintenance
required.
3.
Manual assembly of
individual components into a functioning unit was required.
4.
Commercial production
was difficult and costly.
THIRD GENERATION (1964 - 1975)
Advances in electronics
technology continued and the advent of "microelectronics" technology
made it possible to integrate large number of circuit elements into very small
(less than 5 mm square) surface of silicon known as "chips". This new
technology was called "integrated circuits" (ICs). The third
generation was based on IC technology and the computers that were designed with
the use of integrated circuits were called third generation computers.
Advantages
1.
Smaller in size as
compared to previous generation computers.
2.
Even more reliable than
second-generation computers.
3.
Even lower heat
generated than second generation computers.
4.
These computers were
able to reduce computational times from microseconds to nano seconds.
5.
Maintenance cost is low
because hardware failures are rare.
6.
Easily portable.
7.
Totally general purpose.
Widely used for various commercial applications all over the world.
8.
Less power requirement
than previous generation computers.
9.
Commercial production was
easier and cheaper.
Disadvantages
1.
Air-conditioning
required in many cases.
2.
Highly sophisticated
technology required for the manufacture of IC chips.
FOURTH GENERATION (1975 ONWARDS)
Initially, the integrated
circuits contained only about ten to twenty components. This technology was
named small scale integration (SSI). Latter, with the advancement in technology
for manufacturing ICs, it became possible to integrate upto a hundred
components on a single chip. This technology came to be known as medium scale
integration (MSI). Then came the era of large scale integration (LSI) when it
was possible to integrate over 30,000 components onto a single chip. Effort is
still on for further miniaturization and it is expected that more than one
million components will be integrated on a single chip known as very large
scale integration (VLSI).
A fourth generation
computer, which is what we have now, has LSI chips as its brain. It is LSI
technology, which has led to the development of very small but extremely powerful
computers. on. A whole computer circuit was soon available on a single ship.
They became inexpensive to make and suddenly it became possible for anyone and everyone
to own a computer.
Advantages
1.
Smallest in size because
of high component density.
2.
Very reliable.
3.
Heat generated is
negligible.
4.
No air conditioning
required in most cases.
5.
Much faster in
computation than previous generations.
6.
Hardware failure is
negligible and hence minimal maintenance is required.
7.
Easily portable because
of their small size.
8.
Totally general purpose.
Disadvantage
1.
Highly sophisticated
technology required for the manufacture of LSI chips.
FIFTH GENERATION (YET TO COME)
Scientists are now at work
on the fifth generation computers - a promise, but not yet a reality. They aim
to bring us machines with genuine I.Q., the ability to reason logically, and
with real knowledge of the world. Thus, unlike the last four generations that
naturally followed its predecessor, the fifth generation will be totally
different and totally new.
In structure it will be
parallel (the present ones are serial) and will be able to do multiple tasks
simultaneously. In functions, it will not be algorithmic (step by step, with
one step at a time). In nature, it will not do just data processing (number
crunching) but knowledge processing. In
programming, it will interact with humans in ordinary language (unlike BASIC,
COBOL, FORTRAN, etc. which present computers need). And in architecture, it
will have KIPS (Knowledge Information Processing System) rather than the
present DIPS/LIPS (Data/Logic Information Processing System).
The odds of coming out
with a fifth generation computer are heaviest for Japan. They have already started
work in this direction few years back. Japan has chosen the PROLOG (Programming
in Logic) language as its operating software and plans to have the final
machine talk with human beings, see and deliver pictures and hear the normal,
natural language.
Analog computer
The term analog does
not relate to how the computer is powered and it
is possible to have electronic analog computers.
The characteristics of an analog computer mean it can be better than a digital computer
at particular tasks.
A computer
is simply a machine which processes data in a set fashion or, to put it another
way, calculates. Today most computers are digital and work by reducing all data
to binary numbers before processing. Analog
computers go back thousands of years but vary from digital computers in only
two fundamental ways.
The first is that an analog computer works in
parallel. This means it can carry out multiple tasks simultaneously. A digital computer, even though it may work considerably faster,
can only perform one calculation at any one instant. The only way around this
in a digital computer is parallel computing,
where a single machine has multiple processors. Even then, programs must often
be rewritten to take advantage of this.
The second difference is that
an analog computer
handles continuous variables, while a digital computer
works with discrete numbers. The difference between these is that continuous
variables can include every conceivable number, even irrational numbers.
Digital Computers
On the other hand a digital
computer operates on digital data such as numbers. It uses binary number system
in which there are only two digits 0 and 1. Each one is called a bit.
The digital computer is
designed using digital circuits in which there are two levels for an input or
output signal. These two levels are known as logic 0 and logic 1. Digital
Computers can give more accurate and faster results.
Digital computer is well
suited for solving complex problems in engineering and technology. Hence
digital computers have an increasing use in the field of design, research and
data processing.
Based on the purpose, Digital
computers can be further classified as,
- General Purpose Computers
- Special Purpose Computers
Special purpose computer is
one that is built for a specific application. General purpose computers are
used for any type of applications. They can store different programs and do the
jobs as per the instructions specified on those programs. Most of the computers
that we see today are general purpose computers.
Hybrid Computers
A hybrid computer combines
the desirable features of analog and digital computers. It is mostly used for
automatic operations of complicated physical processes and machines. Now-a-days
analog-to-digital and digital-to-analog converters are used for transforming
the data into suitable form for either type of computation.
For example, in hospital’s
ICU, analog devices might measure the patients temperature, blood pressure and
other vital signs. These measurements which are in analog might then be
converted into numbers and supplied to digital components in the system. These
components are used to monitor the patient’s vital sign and send signals if any
abnormal readings are detected. Hybrid computers are mainly used for
specialized tasks.
Mini Computer
These are powerful computer.
These computers come into existence in 1960s at that time mainframe computer
was very costly. Mini computers were available in cheap prices, so users start using
it. 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.
Micro computers:
These computers use a microprocessor chip and this chip is used
instead of CPU means that this microprocessor chip works as a CPU. These
computers are also called personal computers. Two major types of these
computers are laptop or Desktop computers. Only one user uses these computers
at time that's why they are also known as personal computers.
Mainframe Computer
It was a very powerful and
large computer. You can get idea of its power as it can handle processing of
many users at a time. Terminals are used
to connect a user to this computer and users submit their task through
mainframe. Terminal is a device which has keyboard and a screen. By using
terminal users put inputs into the computer and get the output through screen. A
very large and expensive computer capable of supporting hundreds, or even
thousands, of users simultaneously. 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.
Super Computer
The name "super
computer" specifies that these are most powerful computers even than
mainframe. Actually, when we optimize a mainframe computer then we get super
computer.
The fastest and most powerful type of computer Supercomputers are very
expensive and are employed for specialized applications that require immense
amounts of mathematical calculations. For example, weather forecasting requires
a supercomputer. Other uses of supercomputers include animated graphics, fluid
dynamic calculations, nuclear energy research, and petroleum exploration.
The chief difference between
a supercomputer and a mainframe is that a supercomputer channels all its power
into executing a few programs as fast as possible, whereas a mainframe uses its
power to execute many programs concurrently.
