Third Generation ComputersIntegrated Circuits

Computer Generations

Generation in computer terminology is a

change in technology a computer is/was

being used. Initially, the generation term

was used to distinguish between varying

hardware technologies. But nowadays,

generation includes both hardware and

software, which together make up an entire

computer system.

Hardware

• The period of third generation was 1964-1972.

• The third generation of computer is marked by the use of Integrated Circuits (IC's) in place of transistors .A single I.C has many transistors, resistors and capacitors along with the associated circuitry . The I.C was invented by Jack Kilby .This development made computers smaller in size, reliable and efficient.

WHEN?

Jack St. Clair Kilby (November 8, 1923 – June 20, 2005)invented the first Integrated Circuit

WHO?

I.C Transistors

Capacitors Resistors

WHAT?

Generations of I.Cs or chips

Hundreds or even thousands of transistors could be fabricated on a

single wafer of silicon. In addition, these fabricated transistors could be

connected to form logic circuits on the same chip.

Silicon WafersSilicon chips

These I.Cs are more compact than a transistor. Single I.Cs has many

transistors, registers, capacitors, placed on a single this of silicon. So

the computer built of such components become smaller. Some of

the computers developed during this period were:

•IBM 360 – developed by IBM in 1964

•PDP 8 – developed by DEC in 1965

•PDP 11– developed by DEC in 1970

•CRA 1 – developed by CRAY research in 1974

•VAX – developed by DEC in 1978

•TDC 316- 1975

- 16-bit computers. The data used to be recorded in a

punch card, which was then read by a card reading machine, which in turn, used to give signals to the main frame computer.

Software

• In the beginning magnetic core memories were

used. Later they were replaced by semiconductor

memories (RAM & ROM)

• In this generation size of main memory reached

about 100mb.

• Introduced microprogramming

• Microprogramming, parallel processing (pipelining,

multiprocessor system etc), multiprogramming,

multi-user system (time shared system) etc were

introduced.

HOW?

• Operating system software were introduced (efficient sharing of a

computer system by several user programs)

• Cache and virtual memories were introduced (Cache memory makes

the main memory appear faster than it really is. Virtual memory makes it

appear larger)

•High level languages were standardized by ANSI eg. ANSI FORTRAN, ANSI

COBOL etc

• Database management, multi-user application, online systems like

closed loop process control, airline reservation, interactive query systems,

automatic industrial control etc emerged during this period.

Microprogrammingmicroprogramming A method of accomplishing the control

unit function by describing the steps in that function as a sequence of

register-transfer level operations that are much more elementary

than instructions. In this method of designing and building a control unit,

an additional memory, commonly called a microprogram store,

contains a sequence of microinstructions. A number of microinstructions

will be required to carry out an ordinary machine instruction, thus the

microprogram store should be faster – have a shorter cycle time – than

the normal fast memory.

COBOL PL

COBOL (Common Business Oriented Language) was one of the

earliest high-level programming languages. It was developed in

1959 by a group of computer professionals called the Conference

on Data Systems Languages (CODASYL).

•The language that automated business

•Allows names to be truly connotative - permits both long names

(up to 30 characters) and word-connector characters (dashes)

•Offers object, visual programming environments

Class Libraries

•Integration with the World Wide Web

Hello world!

FORTRAN PL

One of the oldest programming languages, the FORTRAN was

developed by a team of programmers at IBM led by John Backus,

and was first published in 1957. The name FORTRAN is an acronym

for FORmula TRANslation, because it was designed to allow easy

translation of math formulas into code.

•Simple to learn

•Machine Independent - allows for easy transportation of a

program from one machine to another.

•More natural ways to express mathematical functions - FORTRAN

permits even severely complex mathematical functions to be

expressed similarly to regular algebraic notation.

Advantages• Smaller in size as compared to

previous generations.• More reliable.• Used less energy• Produced less heat as compared to

the previous two generations of computers.

• Better speed and could calculate data in nanoseconds.

• Used fan for heat discharge to prevent damage.

• Maintenance cost was low because hardware failure is rare.

• Totally general purpose• Could be used for high-level

languages.• Good storage• Versatile to an extent• Less expensive• Better accuracy• Commercial production increased.• Used mouse and keyboard for input.

Disadvantages• Air conditioning was required.• Highly sophisticated technology

required for the manufacturing of IC chips.

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