Unit 2 - generation of computers

Each generation of computer is characterized by a major technological development that fundamentally changed the way computers operate, resulting in increasingly smaller, cheaper, more powerful and more efficient and reliable devices.

The history of computer development is often referred to in reference to the different generations of computing devices. Each generation of computer is characterized by a major technological development that fundamentally changed the way computers operate, resulting in increasingly smaller, cheaper, more powerful and more efficient and reliable devices. Read about each generation and the developments that led to the current devices that we use today.

The different generations are:

First Generation – 1940-1956: Vacuum Tubes
Second Generation – 1956-1963: Transistors
Third Generation – 1964-1971: Integrated Circuits
Fourth Generation – 1971-Present: Microprocessors
Fifth Generation – Present and Beyond: Artificial Intelligence

First Generation – 1940-1956: Vacuum Tubes
Characteristics:
1) These machines were enormous, filling up entire rooms with tens of thousands of vacuum tubes but were much slower than even the cheapest PC available today.
2) They relied on machine language to perform calculations; they could only solve one problem at a time.
3) Input was punched on punch cards or paper tapes and output was produced through printers.
4) Speed was measured in milliseconds (10-3 s)

Advantages:
1) Vacuum tubes were the only electronic components available during those days.
2) Vacuum tube technology made possible the advent of electronic digital computers.

Disadvantages:
1) Too bulky in size and not portable.
2) Unreliable and thousands of vacuum tubes that were used emitted large amount of heat and burnt frequently.
3) Prone to frequent hardware failures and constant maintenance were required.
4) Manual assembly of individual components into a functional unit was required.
5) Commercial production of such computers was not possible.

Second Generation – 1956-1963: Transistors
Characteristics:
1) Transistors were used as basic building block.
2) Second generation computers moved from cryptic binary machine language to symbolic assembly language which is more understandable than machine language. Assembly language allows a programmer to specify instructions in for of words.
3) These were also the first computers that stored their instructions in the memory.
4) They still relied on punched cards and printers for input and output.Speed was measured in microsecond (10-3 s)

Advantages:
1) Smaller in size as compared to first generation computer.
2)More reliable and less heat was generated as compared to first generation computers.
3) Better portability and under commercial use; less hardware failures.

Third Generation – 1964-1971: Integrated Circuits
Characteristics:
1) Computing chip; Integrated circuits (IC) were introduced, which is a basic building block for the components of 3rd generation computers.
2) Concept of multiprogramming was introduced where more than one job resides in the main memory competing for CPU and CPU could be kept more busy.
3) Computational time was measured in nanosecond (10-9 s).

Advantages:
1) Smaller in size as compared to previous generations.
2) More reliable, less heat dissipation; low maintenance cost.
3) Portable and high fault tolerance.
4) Total general purpose and wide commercial use.
5) Easier to use and cheaper than previous generations.

Fourth Generation – 1971-Present: Microprocessors
Initially the integrated circuits contained only about ten to twenty components. This technology is known as SSI (Small Scale Integration). Later with the advancement in technology for manufacturing ICs, it became possible to integrate up to a hundred components on one single chip. This technology is know as MSI (Medium Scale Integration). Then came the era of large scale integration (LSI), when it is possible to integrate over 30,000 components on once single chip. More advanced technologies like Very Large Scale Integration (VLSI) and Ultra Large Scale Integration (ULSI) made possible the development of sophisticated, compact, handheld multi functioning devices with easy interface for interaction.

Advantages:
1) Smallest in size because of density.
2) Very reliable and faster computation speed than previous generation.
3) Negligible hardware failure and cheapest.
4) Totally general purpose, wide range of use and portable.

Fifth Generation – Present and Beyond: Artificial Intelligence
Defining the fifth generation computers is somewhat difficult because the field is still in its infancy. Using recent engineering advances, computers are able to accept spoken word instruction (voice recognition) and imitate human reasoning. The ability to translate a language to another with the help of machine NLP (Natural Language Processing) is now possible which can be one of the components for the fifth generation computer. Super conductor technology, massive parallel processing and bio-chips will be the foundation technology for these computers. Researches are being carried out to make computers think like us.