Fourth Generation of Computers (1971-1981)

Main Features
Major Innovation - LSIC and VLSIC (Micro Processor)
Main Memory - EPROM and SRAM.
External Storage - Floppy Disk and Hard Disk.
Input and Output Devices - Monitor for output.
Languages - Languages and application softwares.
Operating System - MS-DOS and PC-DOS
Size - Micro computer e.g. IBM-PC, Apple Macintosh etc.
The Integrated circuits were more developed and called Small scale integration (SSI), after some time the SSI were more developed and termed as Large scale integration (LSI). There was a great versatility of input/output devices. In 1971, a powerful microprocessor chip INTEL 8008 was introduced. The first microprocessor which is used in personal computers (PC) was INTEL 8080. The 8 inch floppy disk was also introduced in 1971, while hard disk was introduced in 1973. The 5.25 floppy disk was first time used in 1978. The optical disk was developed in 1980. First portable computer "Osborne I" was marketed in 1981. IBM-3033, IBM-370, IBM system 34, IBM system 36, Cray-I, CP/M etc were introduced in this generation.

Advantages of Fourth Generation
1. Smaller in size and much reliable.
2. No cooling system required in many cases.
3. Much faster computation.
4. Portable and cheap.
5. The heat generated was negligible.
6. Totally general purpose computer.


Disadvantages of Fourth Generation
1. Very advanced technology was required to fabricate to the ICs.


Fifth Generation (1981-Onward)

Main Features
Major Innovations - ULSIC (Ultra large scale integrated circuit)
Main Memory - EEPROM, SIMM and DIMM.
External Storage - Modified magnetic and Optical disks.
Input/output Devices - Keyboard, Pointing Device, Scanner as input and Monitor as main output.
Languages - AI (Artificial Intelligence) Expert systems.
Operating System - GUI based e.g. Windows 95, Windows NT.
Size - Very small in size example: Laptop, Note book, Digital Diary, Palm top and Pocket PC.
This generation is started from 1981 and still continued, new technologies are adopted to fabricate IC chips, such as electron beam, X-rays or laser rays. The Very Large Scale Integration
(VLSI) was developed, so the computer became much smaller than ever before. New memory storage device like bubble memory, optical or memory are being designed. the new computer will be controlled by using human voice and will work by giving command in our own language. Future computer will in some way to be intelligent and capable of making decision.

Advantages of Fifth Generation
1. Very large storage capacity.
2. Long bit processor builds.
3. Artificial Intelligence Language developed.


Short Notes

1. Super Computer

These are the largest and fastest machines today where numerical computations are carried out speeds of up to 50 millions operation per second. Super computers are very sophisticated machines designed to perform complex calculations at fastest speeds. Super computers are used to model very large dynamic systems, such as weather patterns national or global weather forecasting, satellite tracking, cold-testing of atomic and nuclear weapon etc. Carry research and Intel are well known producers of Super Computers.


2. Main Frames

A main frame originally meant the cabinet containing the central processor unit of a very large computer. After mini computer became available, the word main-frame comes to refers to the large computer itself.
Mainframes, the biggest and the most productive general purpose systems, that are made to model large dynamic computing need of a big organizations that serve hundreds of terminals all at the same time. A terminal consists of a monitor and keyboard that allow a person to enter information and retrieve it from the computer. These computers are the ultimate in sophistication, flexibility and speed.


3. Mini-Computer

Mini computer are increasingly powerful and do almost any thing that large computers do, only more slowly and at much lower cost than mainframes. This makes it ideal for small companies where capacity and speed of operations in not highly critical. These computers are smaller than mainframe and larger than micro computer in size. A mini computer is a multiprocessing system having terminals attached to it and is capable of supporting 4 to 200 users simultaneously. DEC VAX and IBM AS/400 are commonly used mini-computers.
4. Micro-Computer

Micro-Computers are computers that are powered by microprocessors. Sometimes they are referred as SINGLE CHIP PROCESSOR a SYSTEM-ON-A-CHIP. Micro-computers or personal computers are the smallest computers, designed to be used by individuals for writing, illustrating, budgeting, playing games and communicating with other computers.