Third Generation Of computer

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Third Generation Computer (1964-1975)

The third generation began in 1965 with germanium transistors being replaced by silicon transistors. These computers were designed using IC (Integrated Circuits).In 1958, Jack St. Clair Kilby and Robert Noyce invented the first Integrated Circuit. With advancement in electronic technology with time resulted with the technology of microelectronics. With the help of microelectronic technology it made possible to integrate a large number of circuit components into a single and very small piece of silicon which was known as chips. 

This small chip single Integrated Circuits (IC), circuits consisting of several transistors, resistors, capacitors in it grown on a single chip of silicon, eliminating wired interconnection between components, emerged. From small scale integrated circuits (SSI) which have about 10 transistors per chip, this technology developed to  medium scale integrated (MSI) circuits with 100 transistor per chip. Switching speed of transistors went up by a factor of 10, reliability increased by a factor 10, power dissipation reduced by a factor 10 and the size of transistor switches was also reduced by a factor 10. The effect of this development was the emergence of extremely powerful CPUs with the capacity of carrying out 1 million instructions per second. Several new architectural ideas, such as virtual memory, interrupts, DMA, and base registers, became part of commercial computers and were extensively used.

There were significant improvements in the design of magnetic core memories. The size of the main memories reached about 4 MB. Magnetic disk technology improved rapidly. 100 MB drives became feasible.

Third generation computers are operated on structured programming languages. Structured programming languages are C, FORTRAN AND Pascal. ICs were much smaller, less expensive to produce, more rugged and reliable, faster in operation, dissipated less heat, and consumed much less power than circuits built by wiring electronic components  manually. Hence, third-generation computers were more powerful, more reliable, less expensive, smaller, and cooler to operate than the second generation computers.

Main memory capacities increased to several megabytes and processing speeds jumped to millions of instructions per second (MIPS) as telecommunications capabilities became common. The combined effect of high capacity memory, powerful CPU and large disk memories led to the development of time shared operating systems. Time shared operating systems increased programmer productivity. This  programs to come into widespread use that automated and supervised the activities of many types of peripheral devices and processing by mainframe computers of several programs at the same time, frequently involving networks of users at remote terminals. Integrated circuit technology also made possible the development and widespread use of small computers called minicomputers in the third computer generation.  The remote processing, time-sharing, and multiprogramming operating systems were used in this generation of computer. Users can interact with keyboards, monitors, and interface with an operating system in the third generation of computers.

Parallel advancements in storage technologies allowed the construction of larger magnetic cores based random access memory, and larger capacity magnetic disk and magnetic tapes. Hence, the third-generation computers typically had few megabytes (less than 5 Megabytes) of main memory, and Magnetic disks capable of storing few tens of megabytes of data per disk drive.

Many important on-line systems became feasible. In particular, dynamic production control systems, airline reservation systems, interactive query systems, and real-time, closed-loop process control systems were implemented. Integrated database management systems emerged.

 On software front, high level languages were improved. FORTRAN IV and optimizing FORTRAN compilers were developed. COBOL 68 was standardized by the American National Standards Institute. PL/I of IBM emerged and was quite a powerful  language. Additionally, some more high- level programming languages were introduced during third-generation period. Notably among these were PASCAL and BASIC.

The third generation probably ended by 1975. The improvement in the period 1965-1975 were substantial, but no revolutionary new concept could be identified as heralding the end of the third generation.

Some computers of the third generation which are given below:

• IBM-360 series.
• Honeywell-6000 series.
• PDP (personal data processor).
• IBM 370/168.
• TDC – 316.
• PDP-8.
• PDP-11.
• ICL2900.
• IBM 370.
• VAX

The Characteristics features of third-generation computes are as follows:

1.  They were much powerful than the second- generation computers. They were capable of performing about 1 million instructions per second.

2. They are much smaller than second-generation computers, requiring smaller space.

3.  Although the heat dissipation was much less than second- generation  computers, the rooms/areas in which the third-generation computers were located had to be properly air-conditioned.

4. They consumed much less power than second-generation of computers.

5. They were more reliable and less prone to hardware failures than the second-generation computers.

6. They had faster and larger primary and secondary storage as compared to second-generation computer.

7. They were totally general-purpose machines suitable for both scientific and commercial applications.

8. Their manufacturing did not require manual assembly of individual components into electronic circuits, resulting in reduced human labor and cost involved at assembly stage. Hence, commercial production of these systems was easier and cheaper. However, highly sophisticated technology and expensive setup was required for the manufacture of IC chips.

9.  Standardization of high-level programming languages allowed programs written for one computer to easily ported to another computers and executed on another computer.

10. Timesharing operating system allowed interactive usage and simultaneous use of these systems by a large number of users.

11. Timesharing operating system also made on-line system feasible, resulting in the use of the systems for new on-line applications.

12. Timesharing operating system also made on-line systems feasible, resulting in the use of these systems for new on-line applications.

13. Unbundling of software from hardware gave users of these systems an opportunity to invest only in software of their need and value.

14. The minicomputers of the third generation made computer affordable even by smaller companies.

Advantages of Third Generation Computers

1. With the invention of IC third generation computers are smaller than previous generation computers.
2. They were more reliable than second generation computers.
3. They generate less heat and consume less power than second generation computers.
4. The computation time in this generation was reduced from microsecond to nanosecond.
5. Maintenance cost was low because hardware failure rarely occurred.
6. Third generation computers were portable.
7. They were used widely in various commercial applications all over the world.
8. Manual assembly of individual components was not required in this generation.
9. Commercial production was easier and cheaper.

Disadvantage of Third Generation Computer

1. Air conditioning was still required in many cases.
2. Highly sophisticated technology required for the manufacturing of IC chips.
3. IC chips are not easy to maintain.