The document discusses the five generations of computers from the 1940s to present. The first generation used vacuum tubes and were very large, expensive, and prone to failure. The second generation used transistors, making computers smaller, more reliable, and able to support assembly languages. The third generation used integrated circuits, enabling smaller size and higher level programming languages. The fourth generation used microprocessors and VLSI circuits, leading to the development of personal computers. The fifth generation continues to use more advanced technologies like ULSI, parallel processing, and artificial intelligence.

1. COMPUTER - GENERATIONS
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Computer Generations
Generation in computer terminolog y is a chang e in technolog y a computer is/was being used. Initially, the
g eneration term was used to disting uish between varying hardware technolog ies. But nowadays, g eneration
includes both hardware and software, which tog ether make up an entire computer system.
T here are totally five computer g enerations known till date. Each g eneration has been discussedin detail along
with their time period, characteristics. We've used approximate dates ag ainst each g enerations which are
normally accepted.
Following are the main five generations of computers
S.N.
Generation & Desc ription
1
First Generation
T he period of first g eneration : 1946-1959. Vaccum tube based.
2
Sec ond Generation
T he period of second g eneration : 1959-1965. T ransistor based.
3
T hird Generation
T he period of third g eneration : 1965-1971. Integ rated Circuit based.
4
Fourth Generation
T he period of fourth g eneration : 1971-1980. VLSI microprocessor based.
5
Fifth Generation
T he period of fifth g eneration : 1980-onwards.ULSI microprocessor based
First Generation
T he period of first g eneration was 1946-1959.
First g eneration of computer started with using vacuum tubes as the basic components for memory and circuitry
for CPU(Central Processing Unit). T hese tubes like electric bulbs produced a lot of heat and were prone to
frequent fusing of the installations, therefore, were very expensive and could be afforded only by very larg e
org anisations.
In this g eneration mainly batch processing operating system were used. In this g eneration Punched cards,
Paper tape, Mag netic tape Input & Output device were used.
T here were Machine code and electric wired board lang uag es used.

2. T he main features of First Generation are:
Vacuum tube technolog y
Unreliable
Supported Machine lang uag e only
Very costly
Generate lot of heat
Slow Input/Output device
Hug e size
Need of A.C.
Non portable
Consumed lot of electricity
Some computer of this g eneration were:
ENIAC
EDVAC
UNIVAC
IBM-701
IBM-650
Second Generation
T he period of second g eneration was 1959-1965.
T his g eneration using the transistor were cheaper, consumed less power, more compact in size, more reliable
and faster than the first g eneration machines made of vaccum tubes.In this g eneration, mag netic cores were

3. used as primary memory and mag netic tape and mag netic disks as secondary storag e devices.
In this g eneration assembly lang uag e and hig h level prog ramming lang uag e like FORT RAN, COBOL were
used.
T here were Batch processing and Multiprog ramming Operating system used.
T he main features of Second Generation are:
Use of transistors
Reliable as compared to First g eneration computers
Smaller size as compared to First g eneration computers
Generate less heat as compared to First g eneration computers
Consumed less electricity as compared to First g eneration computers
Faster than first g eneration computers
Still very costly
A.C. needed
Support machine and assmebly lang uag es
Some computer of this g eneration were:
IBM 1620
IBM 7094
CDC 1604
CDC 3600
UNIVAC 1108
Third Generation
T he period of third g eneration was 1965-1971.
T he third g eneration of computer is marked by the use of Integ rated Circuits (IC's) in place of transistors.A

4. sing le I.C has many transistors, resistors and capacitors along with the associated circuitry.T he I.C was invented
by Jack Kilby. T his development made computers smaller in size, reliable and efficient.
In this g eneration Remote processing , T ime-sharing , Real-time, Multi-prog ramming Operating System were
used.
Hig h level lang uag e (FORT RAN-II T O IV, COBOL, PASCAL PL/1, BASIC, ALGOL-68 etc.) were used during
this g eneration.
T he main features of T hird Generation are:
IC used
More reliable
Smaller size
Generate less heat
Faster
Lesser maintenance
Still costly
A.C needed
Consumed lesser electricity
Support hig h level lang uag e
Some computer of this g eneration were:
IBM-360 series
Honeywell-6000 series
PDP(Personal Data Processor)
IBM-370/168
T DC-316
Fourth Generation
T he period of Fourth Generation was 1971-1980.

5. T he fourth g eneration of computers is marked by the use of Very Larg e Scale Integ rated (VLSI) circuits.VLSI
circuits having about 5000 transistors and other circuit elements and their associated circuits on a sing le chip
made it possible to have microcomputers of fourth g eneration. Fourth Generation computers became more
powerful, compact, reliable, and affordable. As a result, it g ave rise to personal computer (PC) revolution.
In this g eneration T ime sharing , Real time, Networks, Distributed Operating System were used.
All the Hig her level lang uag es like C and C++, DBASE etc. were used in this g eneration.
T he main features of Fourth Generation are:
VLSI technolog y used
Very cheap
Portable and reliable
Use of PC's
Very small size
Pipeline processing
No A.C. needed
Concept of internet was introduced
Great developments in the fields of networks
Computers became easily available
Some computer of this g eneration were:
DEC 10
ST AR 1000
PDP 11

6. CRAY-1(Super Computer)
CRAY-X-MP(Super Computer)
Fifth Generation
T he period of Fifth Generation is 1980-till date.
In the fifth g eneration, the VLSI technolog y became ULSI (Ultra Larg e Scale Integ ration) technolog y, resulting
in the production of microprocessor chips having ten million electronic components.
T his g eneration is based on parallel processing hardware and AI (Artificial Intellig ence) software.
AI is an emerg ing branch in computer science, which interprets means and method of making computers think
like human being s.
All the Hig her level lang uag es like C and C++, Java, .Net etc. are used in this g eneration.
AI includes:
Robotics
Neural networks
Game Playing
Development of expert systems to make decisions in real life situations.
Natural lang uag e understanding and g eneration.
T he main features of Fifth Generation are:
ULSI technolog y
Development of true artificial intellig ence
Development of Natural lang uag e processing
Advancement in Parallel Processing
Advancement in Superconductor technolog y

7. More user friendly interfaces with multimedia features
Availability of very powerful and compact computers at cheaper rates
Some computer types of this g eneration are:
Desktop
Laptop
NoteBook
UltraBook
ChromeBook