Generation of Computer

Third Generation (1964-1971) Integrated Circuits

The development of the integrated circuit was the hallmark of the third generation of computers. Transistors were miniaturized and placed on silicon chips, called semiconductors, which drastically increased the speed and efficiency of computers.

Some of its features are :

• ICs were used
• Small Scale Integration and Medium Scale Integration technology were implemented in CPU.
• Keyboards and monitors as the I/O devices instead of punched card & Printouts.
• Smaller & better performance
• Comparatively lesser cost
• Faster processors
• In the beginning magnetic core memories were used. Later they were replaced by semiconductor memories (RAM & ROM)
• Introduced microprogramming
• Microprogramming, parallel processing (pipelining, multiprocessor system etc), multiprogramming, multi-user system (time shared system) etc were introduced.
• Operating system software were introduced (efficient sharing of a computer system by several user programs)
• Cache and virtual memories were introduced (Cache memory makes the main memory appear faster than it really is. Virtual memory makes it appear larger)
• Database management, multi-user application, online systems like closed loop process control, airline reservation, interactive query systems, automatic industrial control etc emerged during this period.
• High level languages were standardized by ANSI eg. ANSI FORTRAN, ANSI COBOL etc

Fourth Generation (1971-Present) Microprocessors
The microprocessor brought the fourth generation of computers, as thousands of integrated circuits were built onto a single silicon chip. VLSI & ULSI is the major achievement of fourth generation of computer. 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.

Some of its Features are:

• Microprocessors were introduced as CPU– Complete processors and large section of main memory could be implemented in a single chip
• Tens of thousands of transistors can be placed in a single chip (VLSI design implemented)
• CRT screen, laser & ink jet printers, scanners etc were developed.
• Semiconductor memory chips were used as the main memory.
• Secondary memory was composed of hard disks – Floppy disks & magnetic tapes were used for backup memory
• Parallelism, pipelining cache memory and virtual memory were applied in a better way
• LAN and WANS were developed (where desktop work stations interconnected)
• Introduced C language and Unix OS
• Introduced Graphical User Interface
• Less power consumption
• High performance, lower cost and very compact
• Much increase in the speed of operation