Generations of Computer 1st to 5th Difference and Characteristics

The earliest computers were large in size. These computers occupied large floor space. They consumed lot of electricity. Their cost was also higher.During last fifty years, the technological improvements have been aimed at reducing the size and electricity consumption. The aim is to reduce cost and at the same time improve the performance and speed.

The computer technology has been aimed at making smaller, cheaper and efficient computers. The development of computers has been very rapid in the last fifty years. The development has been in five distinct stages. Each of these stages is called a generation.

There are five generations

First Generation Computer (1946-1955) ENIAC

The first general purpose computer was designed to meet the requirement of World War II.

The ENIAC (Electronic Numerical Integrator and Calculator) was designed in 1945 at the University of Pennsylvania to calculate figure for thousands of gunnery tables required by the U.S. army for accuracy in artillery firing. It could perform 5000 additions or 500 multiplications per minute. It was a giant machine and needed a great amount of electricity and emitted excessive heat. ENIAC used 18,500 vacuum tubes. The main features of ENIAC can be summarized as:

• ENIAC was a general purpose computing machine in which vaccum tube technology was used. 
• ENIAC was based on decimal arithmetic rather than binary arithmetic.
• ENIAC needed to be programmed manually by setting switches and plugging or unplugging. Thus, to pass a set of instructions to computer was cumbersome and time consuming. This was considered to be the major deficiency of ENIAC.             

    A major breakthrough occurred in the logical design of computers when the concept of a stored program was proposed by Professor John Von Neumann in 1946. His idea was to store machine instructions in the memory of the computer along with data. These instructions could themselves be modified as required by other instructions. This allowed easy implementation of program loops.

 The first use of this principle was designed and commissioned at Cambridge University, U.K. under the guidance of Professor Maurice Wilkies. This computer called ED-SAC (Electronic Delay Storage Automatic Calculator) was completed in 1949 and used mercury delay lines for storage.

In 1951, Eckert and Mauchley, developed the UNI-VAC –I. This computer also used vacuum tubes. With the advent of UNI-VAC, the  prospects of commercial application were perceived. 

Characteristics of First Generation Computers

The main characteristics of first generation computers are following :-

• Vacuum tubes like diodes, triodes and resistors were used for storing data and as capacitors. Since vacuum tubes needed time to be heated, the startup time was very long and the power consumption was very high.
• An excessive amount of heat was generated and therefore these computers had to be  heavily water cooled to avoid overheating.
• They had a limited memory and programming capabilities offered by them were very limited.
• Vacuum tubes got burnt out frequently and needed to be replaced very often.
• Use of ferrite core main memory was started during this time.
• Punched cards were used as input device.
• Binary code or machine language was used for programming.
• Magnetic tapes and magnetic drums were used as secondary memory.
• Towards the end due to difficulties  encountered in use of machine language as programming language, the use of symbolic language which is now called as assembly language started. Assembler, a program which translates assembly language programs to machine language, was made.

SECOND GENERATION COMPUTERS (1955-1964)

The second generation computers with the advent of transistor replacing Vacuum Tubes. A transistor is a two state device made from silicon. It is cheaper, smaller and dissipates less heat than vacuum tube but can be utilized in a similar way as that of vacuum tubes. Unlike vacuum tubes, a glass capsule and vacuum, therefore is called a solid state device. The transistors were invented in 1947 and had launched the electronic revolution in 1950.

One of the main computer series during this time was the IBM 700 series. Each successful number of this series showed increased performance, capacity and reduced cost. In these series, two main concepts I/O channels, an independent processor for input/output and multiplexer, a useful routing device were used.

2nd generation transistor

CHARACTERISTICS OF SECOND GENERATION COMPUTERS

transistors

                The main characteristics of second generation computers are following:

Second generation computers were more advanced in terms of arithmetic and logic Unit and control  Unit than their counterparts of first generation.

• A major event during this period was the invention of magnetic cores for storage  Magnetic cores are tiny rings ( .02 inch diameter) made of fer-rite and can be magnetized in either clockwise or anti-clock wise direction. Magnetic cores were used to construct large random access memories.
• Magnetic disk storage was also developed during this period.
• The higher reliability of computers and large memory availability led to the development of high level languages. FORTRAN, COBOL , Algol were developed during this generation.

With higher speed CPU’s and the advent of magnetic tape and disk storage, operating systems were developed . Good batch operating systems, particularly the ones on IBM 7000 series computers emerged during second generation.

Commercial applications rapidly developed during this period and dominated computer use by mid 1960’s . Payroll, inventory control, marketing, production planning and general ledger systems were developed. A number of applications of operation research such as Linear Programming., Engineering applications increased rapidly.

THIRD GENERATION COMPUTERS (1965-1970)

 Transistor’s and magnetic cores were replaced by Integrated Circuits (IC’s) or Chips.In an Integrated Circuit, the components such as transistors, resistors and conductors are fabricated on semiconductor material such as silicon. Thus, a desired circuit can be fabricated in a tiny piece of silicon rather than assembling several discrete components into the same circuit. Hundreds or even thousands of transistors could be fabricated on a single wafer of silicon. In addition, these fabricated transistors can be connected with a  process of localisation to form logic circuits on the same chip they have been produced.

An integrated circuit is constructed on a thin wafer of silicon which is divided into a matrix of small areas. An identical circuit pattern is fabricated on each of these chips consists of several gates, a useful logic component, and a number of input and output in a housing to protect it. In addition, this housing provides a number of pins for connecting this chip with other devices or circuits.

Some of the examples of third generation computers are IBM system/360 Family and DEC-PDP/8 Systems.

Integrated Circuit

CHARACTERISTICS FEATURES OF THIRD GENERATION COMPUTERS 

The main characteristics features of third generation computers are following:

3rd generation integrated circuit

• IC circuits were started to find their application in the computer hardware replacing the discrete transistor component circuits. This resulted in reduction in the cost and the physical size of the computer.
• Semiconductor (Integrated circuit) memories were started to augment ferrite core memory as main memory.
• The CPU design was made simple and CPU were made more flexible using a technique called micro programming a scheme where programs control the generation of central signals.
• Certain new techniques were introduced to increase the effective speed of program execution. These techniques were pipe lining and multiprocessing.
• The operating systems of computers were incorporated with the efficient methods of sharing the facilities or resources such as processor and memory space automatically.

FOURTH GENERATION COMPUTERS (1976-1998)

With the growth in micro-electronics the IC technology evolved rapidly. One of the major milestone in this technology was the Very Large Scale Integration (VLSI)  where thousands of transistors could be integrated on a single chip. The main impact of VLSI was that, it was possible to produce a complete CPU or main memory or other similar devices on a single IC chip. This implied that mass production of CPU, memory etc. could  be done at a very low cost.

Important Breakthrough in VLSI Technology
Semiconductor Memories

Initially the IC technology was used for constructing processor but soon it was realized that the same technology could be used for construction of memory also. Therefore, the magnetic core memories were replaced by semiconductor memories.

Microprocessors

Intel in 1971 achieved the breakthrough of putting all the components on a single chip. The single chip processor is known as a microprocessor. Intel 4004 was the first microprocessor.  It was a primitive microprocessor designed for a specific application. Intel 8080 which came in 1974 was the first general purpose microprocessor. It was an 8-bit microprocessor.At present, there are 32 and 64 bit general purpose microprocessors available in the market. For example, Intel 486 is a 32 bit processor. Pentium announced by Intel can process 64 bit data at a time. VLSI technology has led to the development of Microcomputers.

VLSI technolody

CHARACTERISTICS FEATURES OF FOURTH GENERATION COMPUTERS

VLSI technolody

The main characteristics features of fourth generation computers are following:

• Medium scale integrated circuits yielded large and very large scale integrated circuits (VLSI) packing about 50,000 transistors in a chip.
• Magnetic core memories were replaced by semiconductor memories.
• Emergence of microprocessors led to the emergence of extremely powerful personal computers. Computer cost came down so rapidly that professionals had their own computer to be used in their offices and homes.
• Hard  disks provided a low cost, high capacity secondary memory.
• A major development was the decentralization of computer organization. Individual microprocessor controls for terminals and peripheral devices allowed the CPU to concentrate on processing the main program.

FIFTH GENERATION COMPUTERS (YET TO COME)

The fifth generation computers (Tomorrow’s computers) are still under research and developmental stage.

            These computers would have artificial intelligence. 

FACE RECOGNITION

They will use ULSI (Ultra Large Scale Integration) chips in place of VLSI chips.

ulsi chip technology

One ULSI chip contains millions of components on a single IC. The most important feature of fifth generation computers is that they will use an intelligence software.

THUMB IMPRESSION

 This software will enable the user to tell computer ‘what to do and what not to do’ and ‘how to do’ by using intelligence programming and knowledge based problem solving techniques.

Example: 

robots 

• ROBOTS have few features of fifth generation computers , 
• today we uses finger print sensors in our mobile phones,
• face unlock system ,  infrared are also may be the examples of fifth generation examples.

COMPARISON BETWEEN THE GENERATIONS OF COMPUTER

The comparative features of computers of various generations are shown below:

COMPARISON BTW. GENERATIONS OF COMPUTER