Fourth Generation (1971-1990) dedicated to Microprocessors
The microprocessor brought the fourth generation of computers, 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 Intel 4004 chip, developed in 1971, located all the components of the computer—from the central processing unit and memory to input/output controls—on a single chip.
In 1981 IBM introduced its first computer for the home user, and in 1984 Apple introduced the Macintosh. Microprocessors also moved out of the realm of desktop computers and into many areas of life as more and more everyday products began to use microprocessors.
As these small computers became more powerful, they could be linked together to form networks, which eventually led to the development of the Internet. Fourth generation computers also saw the development of GUIs, the mouse and handheld devices.
An IC containing about 100 components is called LSI (Large Scale Integration) and the one, which has more than 1000 such components, is called as VLSI (Very Large Scale Integration). It uses large scale Integrated Circuits (LSIC) built on a single silicon chip called microprocessors. Due to the development of microprocessor it is possible to place computer’s central processing unit (CPU) on single chip. These computers are called microcomputers. Later very large scale Integrated Circuits (VLSIC) replaced LSICs. Thus the computer which was occupying a very large room in earlier days can now be placed on a table. The personal computer (PC) that you see in your school is a Fourth Generation Computer Main memory used fast semiconductors chips up to 4 M bits size. Hard disks were used as secondary memory. Keyboards, dot matrix printers etc. were developed. OS-such as MS-DOS, UNIX, Apple’s Macintosh were available. Object oriented language, C++ etc were developed.
1. They used Microprocessor (VLSI) as their main switching element.
2. They are also called as micro computers or personal computers.
3. Their size varies from desktop to laptop or palmtop.
4. They have very high speed of processing; they are 100% accurate, reliable, diligent and versatile.
5. They have very large storage capacity.
Example: IBM PC, Apple-Macintosh etc.
Microprocessor chip emerged .
Very Large Scale Integrated circuits ( VLSI ) packing about 50000 transistors in a chip.
Magnetic Core memories replaced by semiconductor memories. Semiconductor memory sizes of 16 MB with a cycle of 200 nsecs were in use.
Extremely powerful PCs came. Computer cost came down resulted in their availability inside home and offices. Hard disks cost came down considerably . High capacity secondary storage available .
Networks of computers and distributed computers emerged . Considerable development in Computer Graphics.
Unix OS came resulted in time shared interactive system . Speed of microprocessors and the size of main memory and hard disk went up by a factor of 4 every 3 years.
Powerful chips of various company like IBM, Apple, Intel came in market.
Optical disks emerged for mass storage for read only files .
Availability of Optical disks at low cost saw emergence for multimedia applications.
Fibre optical network which could transmit 100 MB/sec to 1 GB/sec makes it Computer Network’s Age too.
C,C++, PROLOG languages emerged.