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Generations of Computers

1. Introduction: Computer generation means step by step changes and each major change or progress after a period of time. Since inception there are totally five generation of computers. Each of the five generations of computers is characterized by a major technological development that fundamentally changed the way computers operate. Most developments resulted in increasingly smaller, cheaper and more powerful and efficient computing devices.

2. First Generation Computer: Electronic Numerical Integrator And Calculator (ENIAC) was the first valve based computer and taken as first computer of first generation of electronic digital computer. It was made by J. P. Eckert and John W. Mauchly in 1946. EDVAC, EDSAC, UNIVAC are some other examples of computer of this generation.

This generation computer possessed the following characteristics:
i) Used thermionic valves or vacuum tube or electronic valve;
ii) Used Mercury line for storage and paper tapes and punched cards were also used;
iii) Computer programming was mainly done in machine language;
iv) All the computers were of very big size and so required very large space;
v) The computers were very costly;
vi) Limited programming capabilities, memory;
vii) Slow operating speed and restricted computing capacity;
viii) High power consumption (each vacuum tubes consumed about half a watt power);
ix) Vacuum tubes used filament as a source of electron; they have a limited life.
x) Large amount of heat generated from the vacuum tubes and so they needed air-conditioning.

3. Second Generation Computer: The invention of transistor (short names for transfer resistor) in 1948 led to the development of second generation of computer. Their main disadvantages were that the commercial productions of transistors were difficult and expensive; again, the manual assembly of individual components into a functioning unit was required. Examples of second generation of computer include UNIVAC-1108, IBM 700, 1401, CDC 1604, 3600.

The second generation computers are characterized by the following:
i) Transistors replaced the vacuum tubes completely;
ii) Use of magnetic cores for memory storage. Magnetic drum, magnetic disc, punched card were also used for storage purpose;
iii) Use of high level language like FORTRAN, COBOL, Algol, SNOBOL, etc.;
iv) Due to the use of transistors the sizes turned to be smaller;
v) Less costly in comparison to the first generation of computer;
vi) Memory capacities were about 100 Kilobyte;
v) Reduction in computation time from millisecond to microsecond;
vi) Transistors consume only a tenth of power as required by vacuum tubes;
vii) Transistors have no filament to burn as against the first generation of computer so they were more reliable;
ix) Less heat was generated due to the use of transistor but still needed air conditioning and frequent maintenance.

4. Third Generation Computer: The third generation began in 1965 with germanium transistors being replaced by silicon transistors (integrated circuit). Integrated circuit is a circuit consisting of transistors, resistors and capacitors grown on a single chip of silicon eliminating wired interconnections between components. Highly sophisticated technology was required for the manufacture of the chips, but still commercial production become easier and not so expensive. Remote processing and time sharing is also an added advantage of this generation of computer. Example: IBM 360 Series, ICL 1900 series, IBM 370/168, ICL 2900, Honeywell 6000 series, etc.

This generation computer has the following characteristics
i) Use of integrated circuit;
ii) Use of semiconductor memories in addition to, and later instead of, ferrite core memory. The two main types of semiconductor memory are Read-Only Memory (ROM) and read-and-write memories called Random Access Memory (RAM);
iii) Extensive use of high level programming languages;
iv) Smaller size and better performance, more flexibility with input/output;
v) Less costly in comparison to the second generation of computer and become popular as minicomputer and are quite portable;
vi) Memories improved to 4 Megabytes;
vii) Reduction in computational time from microseconds to nanoseconds;
viii) Lower heat generation and quite less power requirement;
ix) More reliable in comparison to the second generation of computer;
x) Air conditioning required in many cases;

5. Fourth Generation Computer: The fourth generation of computer may be identified by the advent of the microprocessor chip. The whole computer CPU except primary memory is placed on a single chip. This chip is known as microprocessor. Examples: Intel 4004, Apple series I and II, spectrum 7, etc.

This generation computer has the following characteristics:
i) Use of large scale and very large scale integrated circuits (VLSI) packing about 50,000 transistors in a chip;
ii) Magnetic core memories were replaced by semiconductor memories;
iii) Sophisticated programs and languages for special application. In the area of language “C” language became popular.
iv) Increasing use of microcomputer;
v) Low cost;
vi) Increased storage;
vii) Considerably faster and smaller;
viii) Heat generated is negligible and even air conditioner is not always required;
ix) Network of computers and distributed computer systems were developed;
x) Modular design, versatility and compatibility.

6. Fifth Generation Computer: The fifth generation of computer is in the process of full development. The goal of fifth-generation computing is to develop devices that respond to natural language input and are capable of learning and self-organization. The computer of this generation is expected to be a new and unique of its kind having the artificial intelligence i.e. the ability to reason logically and with the real knowledge of the world, behaving almost like a human being in the sense of talking, seeing, hearing and utilizing human language. There are some applications, such as voice recognition, that are being used in the fifth generation computer today. The use of parallel processing and superconductors is helping to make artificial intelligence a reality. Quantum computation and molecular and nanotechnology will radically change the face of computers in years to come.

The Fifth Generation Computer Systems project (FGCS) was an initiative by Japan’s Ministry of International Trade and Industry, begun in 1982. It aimed to create an “epoch-making computer” with-supercomputer-like performance and to provide a platform for future developments in artificial intelligence. There was also an unrelated Russian project also named as fifth-generation computer.

7. Conclusion: In the history of computing hardware, computers using vacuum tubes were called the first generation; transistors and diodes, the second; integrated circuits, the third; and those using microprocessors, the fourth. Whereas previous computer generations had focused on increasing the number of logic elements in a single CPU, the fifth generation, it was widely believed at the time, would instead turn to massive numbers of CPUs for added performance. The term “fifth generation” was intended to convey the system as being a leap beyond existing machines.

Vacuum tube-based computers were in use throughout the 1950s. Vacuum tubes were largely replaced in the 1960s by transistor-based computers. When compared with tubes, transistors are smaller, faster, cheaper, use less power, and are more reliable. In the 1970s, integrated circuit technology and the subsequent creation of microprocessors, such as the Intel 4004, caused another generation of decreased size and cost, and another generation of increased speed and reliability. By the 1980s, computers became sufficiently small and cheap to replace simple mechanical controls in domestic appliances such as washing machines. The 1980s also witnessed home computers and the now ubiquitous personal computer. With the evolution of the Internet, personal computers are becoming as common as the television and the telephone in the household.
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