Generations of Computers and Their Characteristics

Generations of Computers can be generalized into mainly five generation :
1. First Generation Computers –1942 to 1954
2. Second Generation of Computers -1955 to 1964
3. Third Generation of Computers- 1965 to 1974
4. Fourth Generation Computers- 1975– till now
5. Fifth Generation of Computers – Still in Process

1. First Generation Computers (1942 to 1954) – Based on Vacuum Tubes

The first generation computers were used vaccum tubes as the main electronic part. For memory devices punch card and paper tapes were used. Magnetic drums are also used for storage .At that time memory was very expensive. Electronic time per calculation ranged from 0.1 milliseconds to1 milliseconds. They uses two types of computer programming languages, machine language and assembly language. A list of popular first generation computers ENIAC, UNIVAC,EDVAC, and EDSAC.

A) Computer Characteristics & Capabilities –

Size – Relatively big size .Size was equivalent to a room.
Speed – slow speed, hundred instructions per second.
Cost – cost was very high.
Language– Machine and Assembly Language.
Reliability – high failure rate , Failure of circuits per second.
Power– high power Consumption and it generated much heat.

B) Trends and Developments in Computer Hardware-

Main Component – based on vacuum tubes
Main memory –Magnetic drum
secondary Memory – Magnetic drum & magnetic tape.
Input Media – Punched cards & paper tape
Output Media – Punched card & printed reports.
Example – ENIAC, UNIVAC, Mark –I,mark-III , IBM 700 series , IBM 700 series ,IBM 701 series IBM 709 series etc.

2.Second Generation of Computers (1955 to 1964) – Based on Transistor

The invention of transistor lead to start the second generation of computers. Vaccum tubes are replaced by transistors. For data storage magnetic tapes and magnetic tapes and magnetic disks were used. For programming purpose besides machine and assembly languages, high level languages were also used like FORTRAN, COBOL and BASIC etc.
A) Computer Characteristics & Capabilities –

Size – Smaller than first generation Computers.
Speed – Relatively fast as compared to first generation, thousand instructions per second.
Cost – cost Slightly lower than first generation.
Language – Assembly Language and High level languages like FORTRAN, COBOL,BASIC.
Reliability – Failure of circuits per days.
Power– Low power Consumption.

B ) Trends and Developments in Computer Hardware-

Main Component – Based on Transistor.
Main Memory – Magnetic core.
Secondary Memory – Magnetic tape & magnetic Disk.
Input Media – Punched cards
Output Media – Punched card & printed reports.
Example – IBM-7000,CDC 3000 series, PDP1,PDP3,PDP 5 ,PDP8 ,ATLAS,IBM-7094 etc.

3. Third Generation of Computers (1965 to 1974) – Based on Integrated Circuit

In this generation of computers transistors are replaced by its integrated form, known as integrated Circuits(IC). Mini computers were introduced in this generation. Multiprogramming facility was developed.Size, cost, power requirement and heat generation decreased. High level languages were used in this generation. Processing speed and storage capacity used of computer increased.

A) Computer Characteristics & Capabilities –

Size – Smaller than Second generation Computers. Disk size mini computers.
Speed – Relatively fast as compared to second generation, Million instructions per second (MIPS).
Cost – cost lower than Second generation.
Language– High level languages like PASCAL, COBOL,BASIC,C etc.
Reliability – Failure of circuits in Weeks.
Power– Low power Consumption.

B) Trends and Developments in Computer Hardware-

Main Component – Based on Integrated Circuits (IC)
Primary Memory – Magnetic core.
Secondary Memory– Magnetic Tape & magnetic disk.
Input Media – Key to tape & key to disk
Output Media – Printed reports & Video displays.
Example – IBM-307 Series ,CDC 7600 series, PDP (Personal Data processer ) II etc.

4. Fourth Generation of Computers (1975– till now )- Based on VLSI Microprocessor

The fourth generation computers started with the invention of Microprocessor. Software is user friendly. Storage capacity is high. Size, cost, power requirement, heat generation decreased compared to the previous generation. Problem-oriented fourth generation language (4GL) is used to develop the program.
A) Computer Characteristics & Capabilities –

Size – Typewritter size micro Computer.
Speed – Relatively fast as compared to Third generation, Tens of Millions instructions per second.
Cost – Cost lower than third generation.
Language– High level languages like C++,KL1 , RPG, SQL.
Reliability – Failure of circuits in months.
Power– Low power Consumption.

B) Trends and Developments in Computer Hardware-

Main Component – Large scale integrated (LSI) Semiconductor circuits called MICRO PROCESSOR or chip and VLSI(Very Large scale integrated).
Main Memory – Semi conductor memory like RAM, ROM and cache memory is used as a primary memory.
Secondary Memory – Magnetic disk, Floppy disk, & Optical disk (CD,DVD).
Input Media – keyboard.
Output Media – Video displays ,Audio responses & printed reports.
Example – CRAY 2, IBM 3090/600 Series, IBM AS/400/B60 etc.

5.Fifth Generation of Computers ( Still in Process)-Based on ULSI Microprocessor ,AI

In this generation of computer Artificial Intelligence (AI) concept is adopted. The computers have intelligence quality, default assumptions, Decision making capability etc. through these concepts expert systems. Knowledge based systems, Decision Support System are developed. Robots are the common example of this type of system.
Generally this generation of system is expected to be intelligent as mankind. It may be hear, understand and work as human being. Research and development are continued.

A) Computer Characteristics & Capabilities –

Size –Credit card size micro computers.
Speed – Billions instructions per second.
Cost – Cost Slightly lower than first generation.
Language– Artificial Intelligence (AI) Languages like LISP, PROLOG etc
Reliability – Failure of circuits in year.
Power– Low power Consumption.

B ) Trends and Developments in Computer Hardware-

Main Component – based on ULSI ( Ultra Large scale integrated) Circuit .that is also called Parallel Processing method.
Memory – Optical disk and magnetic disk.
Input Media – Speech input, Tactile input.
Output Media – Graphics displays, Voice responses.
Example – Lap-Tops, palm –Tops, Note books ,PDA (personal Digital Assistant ) etc.