FOURTH GENERATION COMPUTERS
After 1971 the fourth generation computers were built. The fourth generation computers were the extension of third generation technology. The fourth generation computers emerged with development of the VLSI (Very Large Scale Integration).With the help of VLSI technology microprocessor came into existence. The computers were designed by using microprocessor, as thousands of integrated circuits were built onto a single silicon chip. What in the first generation filled an entire room could now fit in the palm of the hand. The fourth generation computers became more powerful, compact, reliable and affordable. As a result, they give rise to personal computer (PC) revolution.
For the first time in 1981 IBM introduced its computer for the home user and in 1984 Apple introduced the Macintosh Microprocessor.
1) The fourth generation computers have microprocessor-based systems.
2) They are the cheapest among all the computer generation.
3) The speed, accuracy and reliability of the computers were improved in fourth generation computers.
4) Many high-level languages were developed in the fourth generation such as COBOL, FORTRAN, BASIC, PASCAL and C language.
5) A Further refinement of input/output devices was developed.
6) Networking between the systems was developed.
After 1971 the fourth generation computers were built. The fourth generation computers were the extension of third generation technology. The fourth generation computers emerged with development of the VLSI (Very Large Scale Integration).With the help of VLSI technology microprocessor came into existence. The computers were designed by using microprocessor, as thousands of integrated circuits were built onto a single silicon chip. What in the first generation filled an entire room could now fit in the palm of the hand. The fourth generation computers became more powerful, compact, reliable and affordable. As a result, they give rise to personal computer (PC) revolution.
For the first time in 1981 IBM introduced its computer for the home user and in 1984 Apple introduced the Macintosh Microprocessor.
CHARACTERISTICS
2) They are the cheapest among all the computer generation.
3) The speed, accuracy and reliability of the computers were improved in fourth generation computers.
4) Many high-level languages were developed in the fourth generation such as COBOL, FORTRAN, BASIC, PASCAL and C language.
5) A Further refinement of input/output devices was developed.
6) Networking between the systems was developed.
Fourth Generation Languages (4GL)
The examples of 3GLs given above are all procedural languages because the programmer must list each instruction and indicate the order that these steps are to be executed through the use of logical control structures (Sequence-Selection-Iteration). Fourth Generation Languages are non-procedural languages. This means that the programmer does not specify a step-by-step method for executing a given problem. Instead, the inputs and required outputs are given and it is left up to the language to determine the step-by-step details.
The major disadvantage of 4GLS is that the resulting programs may not use the computer's processing power efficiently. Consequently more powerful computers are needed to run this type of program. The most significant advantage, however, is that 4GL programs are much easier to write. They contain a minimum of syntax rules and even people not trained as programmers can write applications.
One of the more common forms of 4GLs are query languages. These are frequently used to retrieve information from databases. An example of a query is "display all clients with date-of-birth before 1931". Other types of 4GL are report generators and application generators.
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