Computer Generation

The First Generation (1951 – 1958)

•         The Vacuum Tube

 A sealed glass or metal container, withdraw from to a high degree of vacuum, through which controlled by flow of electrons is directed. The first computer used vacuum tubes as on/off switches to indicate the 0s and 1s in digital computations

          The first generation computer used vacuum tubes as CPU components. It used   

          Machine language or assembly language for programming. Magnetic tape / Drum

         Were used as secondary memory. Punched cards paper tape were invented to

        Feed programs and data and to get results.

The ENIAC (Electronic Numerical Integrator and Computer), developed by John Mauchly and J.Presper Eckert in 1946

ENIAC contained approximately 18,000 light-bulb size electronic vacuum tubes that controlled the flow of electric current and weight 30 tones with 1500 square ft.

During this generation, the language used in programming was Machine language

The UNIVAC (universal automatic computer) was installed in 1951.

The EDVAC (Electronic Discrete variable Automation Computer)

Disadvantages of vacuum tubes:-

1.    Large in size

2.    Slow

3.    High maintenance

4.    Produces lots of heat

5.    Very unreliable

6.    Requires bulky power supplies

7.    High voltages can present an electric shock hazard

 Second Generation (1959 – 1964):-

•     The Transistor

 Developed by three scientist (J.Bardeen, H.W.Brattain and W.Shockley), a small device that transfer electronic signals across a resistor

Is an electronic switch that alternatively allows electronic signals to pass

Able to alternate between “ON” and “OFF” many millions times per second

·       Importance : -

1.    Transistors were used in computers in place of vacuum tubes.

2.    Magnetic ferrite –core memory was used as main memory, which is a random –access non-volatile memory.  The memory capacity of the second –generation computer was about 1K bytes.  Magnetic disks and magnetic tapes were used as secondary memory. 

3.    Machine dependent high-level languages like FORTRAN, COBOL, and ALGOL, were developed used as programming language. During this generation, the language is used in programming was Assembly language, also called Symbolic language. Assembly languages use abbreviations for instructions (e.g L for Load) rather than numbers.

4.     Example of second generation of computers are:-

IBM 1620 (1960) IBM 7090 (1960) PDP 5 (1963), PDP 8 (1965),

5.    Application  :- industry and commercial organizations :- preparation of pay roll , inventory control, marketing, product planning, general- ledger system, research, scientific and engineering analysis, design. Etc.

        Advantages:

1. Smaller in size than vacuum tubes
2. Needed no warm-up time
3. More reliable
4. Consumes less energy
5. Faster

Third Generation (1965 – 1974):-

•         The Integrated Circuit (IC)

•     Is a complete electronic circuit on a small chip of silicon that comprising many miniature transistors and other electronic components

•     Are made of silicon because it is a semiconductor

•     It has dozens, hundreds or millions of electronic components

•     In the beginning the third –generation computers used magnetic core memory as main memory. It memory capacity size is 4 megabytes, magnetic disks were used as secondary memory, magnetic tapes were used as back-up memory . 100 M BYTES DISK drives were available. Semiconductor memory (RAM & ROM) replaced magnetic core type main memory.

•     Example of third- generation computers are: IBM/370 series (1970), CDC 7600(1969), PDP 11 (1970, 16 bit computer) etc.

•     Application: --- Database management, multi-user application, on-line systems, like closed –loop process control, airline reservation, automatic industrial control etc.

    Desirable characteristics:-

1. Reliability
2. Compactness
3. Low cost

The Fourth Generation (1971 – Present): - 

•          The Microprocessor

·         Is a unit of packaged computer circuitry (an entire CPU, complete with memory, logic and control circuits), on a single chip that is manufactured from a material called silicon at a very small scale

·         Contains thousands of micro miniature electronic of components, mainly transistors on a tiny chip

·         Are 100 times smaller than first generation computers

·         The fourth generation computers use microprocessor (s) as CPU. Memory chips of 256 M BITS CAPACITY ARE AVAILABLE. DISK DRIVE 2 gb to 75 GB, speed up to 15,000 r.p.m are available. Optical disks, CD-ROMs which stores much more data as compared to magnetic disks are used in computers as read – only memory.

·         Example of fourth generation of computers:-

·         Gray’s CSO-16 Gflops (1991), T3E-90, 1.8

·         Teraflops (1998).

·         Application:  -industrial, control,

·         Instrumentation, consumer, application, research, work, analysis, and design, games, banking services, office, military, equipment, education, communication etc.

The Fifth Generation: Present & Beyond

v Fifth generation computing devices, based on Artificial Intelligence (AI), are still in development, though there are some applications, such as voice recognition and robotics, that are being used today

v The goal of fifth generation computing is to develop devices that respond to Natural language input and are capable of learning and self-organisation