The document discusses the five generations of computers from the 1940s to present. Each generation saw improvements in technology, from vacuum tubes in first generation computers to integrated circuits and microprocessors today. Key developments included increased processing speed and memory capacity, smaller size and power consumption, multi-user systems, high-level programming languages, personal computers, and networking capabilities like the internet.

1. Generations of Computer
• ‘Generation’ in computer terms is steps in
technology.
• It provides a framework for the growth of the
computer industry.
• It distinguishes between varying hardware and
software technologies.
• There are five computer generations known till today
as :
– First Generation (1942-1955)
– Second Generation (1955-1964)
– Third Generation (1964-1975)
– Fourth Generation (1975-1989)
– Fifth Generation (1989-Present)
• Each of these generations are describe in next
slides.

2. First Generation
• First Generation (1942-1955)
– They were the fastest calculating devices of their time.
– Too bulky in size requiring large rooms for installation.
– Thousands of vacuum tubes that were used emitted large amount of heat and
burn out frequently. Rooms were they were installed had to be properly air
conditioned.
– Each vacuum tube consumed about half a watt of power and as each
computer had thousands of vacuum tubes, the power consumption was very
high.
– As vacuum tubes used filaments, they had a limited life.
– Required constant maintenance.
– Thousands of components were assembled manually into functioning circuits.
So the commercial production was costly, difficult and time consuming.
– As they were difficult to program and use they had limited commercial use.
– The first generation computers are UNIVAC I and IBM-701 which used
assembly language as their programming language.
– There was no concept of operating system during the era of first generation of
computers.
– The first generation computers were mainly used by highly skilled personnel
since it required understanding of logical structures of computer and the
assembly programming language.

3. Second Generation (1955-1964)_1
• The era of second generation of computer
was during 1955 to 1964.
• The new electronic switching device called
transistor were used in second generation of
computer.
• The transistors were developed at Bell
Laboratories in 1947 by John Bardeen, Willian
Shockley and Walter Brattain.
• Transistors proved to be much better
electronic switching device than vacuum
tubes used in first generation.

4. Second Generation (1955-1964)_2
• Properties of Transistors
– They were made of germanium semiconductor material
which was easier to handle compare to vacuum tubes
made from glass.
– They were highly reliable and faster (ten times) than
tubes.
– The switching circuits made of transistors could operate
faster.
– The power consumption was one tenth as of tubes power
consumption.
– They were much smaller in the size.
– Less expensive to produce.
– They generated less heat compare to vacuum tubes.

5. Second Generation (1955-1964)_3
• In other words the second generation of computers were
more powerful, more reliable, less expensive, smaller and
cooler to operate than the first generation.
• They had faster and larger primary and secondary storage
devices.
• In second generation of computers used high-level
programming languages and batch processing concept.
• The high-level programming languages like FORTRAN,
COBOL, ALGOL, SNOBOL were developed during the
second generation.
• Batch operating system allows multiple jobs to be bunched
together and submitted at a time, and the transition of one job
to another is done automatic once the previous job is
finished.

6. Second Generation (1955-1964)_4
• Due to the development in second generation the
use of computers introduced various business
applications like payroll, inventory control, marketing
and production planning.
• It also opened new profession of programmers and
system analysts in computing, oriented towards
usage rather than design of computers.
• The second generation computer was IBM-1401 and
the programming language was Autocoder.
• In this generation there was introduction of magnetic
storage medium as magnetic tapes.
• The main memory used magnetic cores strung in
meshed wires to construct RAM.

7. Third Generation (1964_1975)_1
• The era of third generation of computer was during
1964 to 1975.
• The integrated circuit technology was used in this
generation to build computers.
• Integrated circuits (IC) are circuits consisting of
several electronic components like transistors,
resistors and capacitors grown in a single chip of
silicon.
• This IC technology was known as ‘microelectronics’
technology because it integrated large number of
circuits into very small silicon ‘chip’.
• In 1958, Jack St. Clair Kilby and Robert Noyce
invented the first IC.
• The IC technology was named as Small Scale
Integration (SSI) .

8. Third Generation (1964_1975)_2
• During third generation of computer, the
software technology followed standardization.
• In 1966, ANSI (American National Standard
Institute) standardized FORTRAN and
COBOL languages.
• The BASIC language was designed as
interpreter. FORTRAN and COBOL languages
used compiler technology.
• The computers were IBM – 360 series and
DEC (Digital Equipment Corporation) PDP
(Programmed Data Processor) series.

9. Third Generation (1964_1975)_3
• The features of third generation of computers are :
– They were more powerful, smaller in size and faster than
second generation of computers. They consumed less
power.
– It used IC chips which required less hardware
maintenance.
– They were general purpose machines suitable for both
scientific and commercial applications.
– The manufacturing did not required manual assembly,
which reduced labor and cost, hence they were cheaper
and popular for use in various applications.
– These computers used standardized high level langauges
and timesharing operating systems.
– Timesharing operating system helped to improved
productivity of programmers and users.

10. Fourth Generation (1975-1989)_1
• The era of fourth generation of computer was during
1975 to 1989.
• The number of electronic components packed on a
silicon chip doubled each year after 1965.
• This progress soon led to the era of LSI (Large Scale
Integration) and VLSI (Very Large Scale Integration)
which led to the development of microprocessor.
• A microprocessor contains all the circuits needed to
perform arithmetic logic and control functions on a
single chip.
• Using this microprocessor the complete computer
was build, adding few additional primary storage
chips and other peripherals, which started new social
revolution – the personal computer (PC) revolution.

11. Fourth Generation (1975-1989)_2
• By 1978, the dominant personal computers were
Apple II from Apple Computer Inc. and TRS-80 model
from Radio Shack division of Tandy Corporation.
• In 1980, IBM realized the up coming market for PC
and its popularity, so they came up with their own PC
in 1981,known as IBM PC.
• Along with PCs development, during forth generation
of computers there were significant development on
large scale computers.
• In addition to improve mainframe systems, the
supercomputers were introduced.
• Supercomputers are based on parallel vector
processing technology.
• During this era RAM storage devices, LAN, WAN,
GUI technology and concepts were introduced.

12. Fourth Generation (1975-1989)_3
• During the fourth generation period, the UNIX
operating system became very popular for use on
large-scale systems.
• ‘C’ programming language became almost standard
programming tool.
• Database and Object-oriented technologies were
used and developed during fourth generation.
• ‘C’ language combines the features of high-level
language and assembly language.
• The enhancement of ‘C’ language using Object-
oriented concepts emerged C++ language.

13. Fifth Generation_1
• The era of fifth generation of computer has started since 1989.
• The trend of further miniaturization of electronic components,
the dramatic increase in the power of microprocessor chips
and the increase of main memory and hard disk continued in
the fifth generation.
• The VLSI technology became ULSI (Ultra Large Scale
Integration) technology in fifth generation.
• The speed of microprocessor, capacity of main memory and
hard disk doubles every eighteen months.
• The power of mainframe system of third & fourth generation
became part of microprocessor architecture in the fifth
generation.
• This resulted the availability of very powerful and compact
computers at cheaper rates and hence the death of traditional
large mainframe systems.

14. Fifth Generation_2
• The features of fifth generation computers are :
– Evolution of portable PCs, the laptops.
– More powerful desktops and workstations.
– Powerful supercomputers.
– They consume less power and less maintenance.
– Portable OS and programming feature.
– Virtual technology for storage, OS and programs.
– Globalization of entire information technology through
internet, databases , data warehousing, data mining.
– Powerful enhancement in object-oriented programs.
– Tremendous user friendliness and much more powerful
multimedia facilities.

15. Summary
• Following table summarizes the main development during the five
generations of computer.
First Generation Second Generation Third Generation Fourth
Generation
Fifth Generation
Vacuum tubes Transistors and
Diodes
Integrated
Circuits (IC)
LSI and VLSI
technology
ULSI technology
Limited storage
capacity
Increased storage More flexible with
input/output
Increased
storage capacity
Larger capacity
storage (RAID,
optical disks)
Slow speed Faster speed Smaller size –
better
performance
Considerably
faster and
smaller
Much faster
Machine and
assembly
languages
Reduction in size
and heat
generation
Extensive usage
of high-level
languages
Modular design,
versatility and
compatibility
Support for more
complex
applications
Problems of
overheating
High-level
programming
languages
(COBOL,
FORTRAN)
Remote
processing and
time sharing
Sophisticated
programs and
languages for
special
applications.
Internet revolution
and still under
development
High
maintenance
PC revolution