Brief Introduction of Computer Generation

Brief Introduction of Computer Generation: 
Generation in computer era provides a framework for the growth of computer industry and generally characterizes the major developments in the computer industry. The modern computer era can be divided into Five generations distinguished by the basic electronic component within the computer. Each new logic unit let the computers faster in speed, smaller in size, more reliable and less expensive than their predecessors. Modern computers came in a variety of shapes, sizes and
costs. Computers were developed in Five different phases known as the Generation of Computers.
Let’s discuss one by one in a little detail :

First Generation (1942-1955) 
The computers of this generation used Electronic Valves (an array of Vacuum Tubes) as the basic component for memory and circuitry for central processing unit. These vacuum tubes were a fragile glass device like electric bulb, that could control and amplify electronic signals. They produced a lot of heat and were prone to frequent fusing/ damaging of the installations. Therefore, they were used very expensive and could be afforded only by very large organizations.

Useful Points
• Period : 1942-1955
• Component used : Vacuum tubes
• Speed : milliseconds
• Maximum memory capacity : 2000 inch
• Mean-time before failure : minutes
• Peripherals : I/O : Punched cards, Paper tape, Magnetic tape, Printer (online) /  Secondary Storage : Punched Cards, Paper Tape, Magnetic Drum, Magnetic Disk etc 
• Operating System : Mainly Batch Processing
• Languages : Machine Code and Electric Wired board
• Application Areas : Payroll Processing, Record Keeping etc.
• Example : ENIAC, EDVAC, EDSAC and IBM 650 ( the first modern digital computer produced on
mass scale)

Second Generation (1955-1964) 
The second generation computer used Semi-conductor transistor instead of vacuum tubes after the invention of transistor by a team led by William Shockley. This generation computers used transistors which were cheaper, consumed less power, more compact in size, more reliable and faster than the vacuum tubes used in first generation computers.

Useful Points
• Period : 1955-1964
• Component used : Transistors
• Speed : microseconds
• Maximum memory capacity : 128000 inch
• Mean-time before failure : days
• Peripherals :
o I/O : Paper tape, Magnetic tape, Visual Display Unit
o Secondary Storage : Paper Tape, Magnetic Drum, Magnetic Disk etc
• Operating System : Multiprogramming, Time-Sharing and Real Time processing
• Languages : Assembly Language, High Level Languages like FORTRON, COBOL etc
• Application Areas : Batch –oriented application like Billing, Payroll processing, Updating
Inventory etc.
• Example : IBM 1401, IBM 7090, IBM 1620, IBM 7094, IBM 700 series, CDC 1604, CDC 3600,

Third Generation (1964-1975) 
The third generation computers used Integrated Circuits (or IC Chips) in which many transistors, resistors, capacitors and other components (circuit elements) are fabricated or integrated and packaged together into a very small surface of silicon known as Chips. This new microelectronic technology was called Integrated Circuits. The IC was invented by Jack Kilby in 1958

Useful Points
• Period : 1964-1975
• Component used : Integrated Circuits (IC)
• Speed : nanoseconds
• Maximum memory capacity : 4 million inch
• Mean-time before failure : weeks to months
• Peripherals :
o I/O : Typewriter terminal, Visual Display Unit, Optical Character Reader etc
o Secondary Storage : Magnetic Disk, Extended Core Storage, Mass Storage devices
• Operating System : Multiprogramming, Time-Sharing, Real Time processing and Remote
• Languages : High Level Languages like FORTRON-II to IV , COBOL , BASIC, ALGOL-68,
PASCAL-1 etc
• Application Areas : Airline System, Market forecasting, Credit Card billing etc
• Example : IBM 360/370 series, ICL 1900 series, PDP 11, RCA Spectra 70 etc.

Fourth Generation (1975 onwards) 
Initially, the Integrated Circuits contained only about 10 to 20 components called Small Scale Integration (SSI). Later on with the advancement in technology for manufacturing Integrated Circuit Silicon Chips (ICS), it became possible to integrate up to a hundred components on a single chip called Medium Scale Integration (MSI). Now the manufacture of integrated circuits became so advanced as to incorporate hundreds of thousands of active components in volume of a fraction of inch, leading to Large Scale or Very Large Scale Integration (VLSI). Integrated Circuits which have the entire computer circuit on a single silicon chip are called Microprocessors. The development
of microprocessors made it possible to place complete CPU of a computer on a single chip.

The first Microprocessor Intel 4004 consisted of 2250 transistors on a microprocessor was designed by Intel Corporation engineer Ted Hoff in 1971. It was 4-bit microprocessor.

Useful Points
• Period : 1975 onward
• Component used : Very Large Scale Integrated Circuits (IC)
• Speed : picoseconds
• Maximum memory capacity : 200 million inch
• Mean-time before failure : months
• Peripherals :
o I/O : Visual Display Unit, Optical Character Reader, Magnetic Ink Character Reader, Voice Recognition, Laser Printer etc
o Secondary Storage : Floppy disk , Hard Disk, CD-ROM, DVD etc
• Operating System : Time-Sharing, Real Time processing and Network Distribution
• Languages : All High Level Languages like C, C++, Java and other 4th generation languages
(declarative languages used in Database )
• Application Areas : Mathematical Modelling, Simuation, Electronic Fund Transfer, Computer
Aided Manufacturing and Design etc
• Example : CRAY-1, CRAY-2, IBM 3090/600, IBM AS/400 HP 9000, IBM ES/9000, VAX etc

Fifth Generation (Future Generation: 1991 onwards ) : 
The fifth generation computers are under development stage. These computers will use Ultra Large Scale Integration (ULSI) chips instead of VLSI. These will be employing two or more processors which compute in parallel. The fifth generation machine are proposed to be based on Parallel Processing hardware and Artificial Intelligence software with genuine I.Q. (Intelligence Quotient). That provide the ability to reason logically and with real knowledge of the world like human do.
Characteristics of future generation computers :
i) Decreasing cost of hardware and software
ii) High speed processing
iii) Knowledge based processing system
iv) Development of natural language processing
v) Advancement in supercomputer technology
vi) Artificial Intelligence , think and behave like  human (humanoid)