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The Third Generation of Computers

Third Generation - Computer Generations

third generation of computers

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Third Generation of Computer

Many people enjoy a misconception that all larger computers are from older generations and small computers are the fourth generation computers. Remember, computers are classified into different generations NOT based on their sizes. Though it is true that the old computers were compelled to be of bigger size (larger components and lack of advanced technology).

The vacuum tubes used in first generation were replaced by transistors in second and which in turn were replaced by ICs (Integrated Circuits) in third generation computers. So, first of all, let’s look at those ICs.

Integrated Circuits

Integrated Circuit (IC) is a small electronic device made out of semiconductor material. The first integrated circuit was developed in the 1950s by Jack Kilby of Texas Instruments and Robert Noyce of Fairchild Semiconductor. – WeboPedia

Types of Integrated Circuits

It is amusing to know that two people thought about the same solution but independently. There is the interesting story about how Robert Noyce got the patent.

Please check R.C. Khanal’s ‘Computer Concept‘ book. He has nicely explained how these IC Chips are manufactured in ‘Computer Generations’ chapter. Notice the terms silicon, wafers, and photolithography.

So, after the invention of IC Chips, it is possible to integrate thousands of registers, diodes, capacitors and many other electronic components and circuitry in a tiny chip.

Integrated circuits are referred with different names like Chips, ICs, Microchips, and so on.

A tiny chip contains the whole electronic network that performs complex tasks.

Types of Integrated Circuits

  • SSI (small-scale integration):
    Up to 100 electronic components per chip
  • MSI (medium-scale integration):
    From 100 to 3,000 electronic components per chip
  • LSI (large-scale integration):
    From 3,000 to 100,000 electronic components per chip
  • VLSI (very large-scale integration):
    From 100,000 to 1,000,000 electronic components per chip
  • ULSI (ultra large-scale integration):
    More than 1 million electronic components per chip
Third Generation of Computers Presentation

Third G​​​​​eneration Computers (1964-1971)

The computers using small scale integration circuits (SSI)and medium scale integration circuits (MSI) are under this class. The invention of IC Chips made it possible to greatly reduce the size of computers with improvement in operation speed (nanoseconds) and reliability.

The most noticeable achievement of third generation is the development of operating systems. The operating systems allowed the machines to run many different applications. These applications were monitored and coordinated by the computer’s memory.

In 1969 AT&T Bell Laboratories programmers Kenneth Thompson and Dennis Ritchie developed the UNIX operating system on a spare DEC minicomputer. UNIX was the first modern operating system that provided a sound intermediary between software and hardware. UNIX provided the user with the means to allocate resources on the fly, rather than requiring the resources be allocated in the design stages. The UNIX operating system quickly secured a wide following, particularly among engineers and scientists at universities and other computer science organizations.

(Source: http://campus.udayton.edu)

User interface devices such as Keyboards and Monitors started from this generation. Similarly, GUI also was started from third generation. These are important development of third generation of computers.

Characteristics of Third Generation Computers

  • Third Generation Computers were based on integrated circuit (IC) technology.
  • Third Generation Computers were able to reduce computational time from microseconds to nanoseconds
  • Third Generation Computers utilized operating systems to centrally control and made it possible for multiple programs to run on a computer
  • Users interacted with computers through keyboards and mouse rather than traditional punched cards and printers.
  • Third Generation Computers devices consumed less power and generated less heat. In some cases, air conditioning was still required.
  • The size of Third Generation Computers was smaller as compared to previous computers
  • Since hardware of the Third Generation Computers rarely failed, the maintenance cost was quite low.
  • Extensive use of high-level language became possible in Third Generation Computers.
  • Manual assembling of individual components was not required for Third Generation Computers, so it reduced the large requirement of labor & cost. However, for the manufacture of IC chips, highly sophisticated technologies were required
  • Commercial production became easier and cheaper.

Examples of Third Generation Computers

IBM 360 - Third Generation Computer

IBM 360

PDP 8 - Third Generation Computer


HP_2115 - Third Generation Computer

HP 2115


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