THE GENERATION OF MODERN COMPUTER

Fig. 1. Types of Computers

Each phase of computer development is called a separate generation of computers. Each phase of development is characterized by type of switching circuits it utilizes.

Most computers today use the idea of ‘stored program computer’ that was proposed by Dr. John Von Neumann in 1945. The Von Neumann architecture is based on three key concept that are:

(i)                Data and instructions (program) are stored in a single read-write memory.

(ii)              The memory contents are addressable by locations.

(iii)            Execution takes place in a sequential fashion i.e. from one instruction to the next unless modified explicitly.

1.     The First-Generation Computers (1945-55)

Fig.1 First Generation Of Computer

   The first generation computers used thermonic valves (vacuum tubes) and machine language was used for giving instructions. The first generation computers used the concept of ‘stored program’. The computers of this generation were very large in size and their programming was a difficult task. Some computers of this generation are being given below:

(a)  ENIAC – This was the first electronic computer developed in 1946 by a term lead by prof. Eckert and Mauchly at the University of Pennsylvania in U.S.A. This computer called Electronic Numerical Integrator And Calculator, used high speed vacuum tube switching devices. It has a very small memory and it was used for calculating the trajectories of missiles. It took 200 microseconds for addition and about 2800 microseconds for additions for multiplication. This gaint machine was 30 x 50 feet long, weighed 30 tons, contained 18000 vacuum tubes, 70,000 resistors, 10,000 capacitors, 6000 switches, used 150,000 watt of electricity. When ENIAC was built, it was 5000 times faster than the closest competitor, the Harvard MARK-I

(b)  EDVAC - The binary arithemetic was used in the construction of a computer called the Electronic Discrete Variable Automatic Computer (EDVAC), completed in 1950. The Von Neumann concept of stored programs was also applied in EDVAC.With this the operation becames faster since the computer could rapidly access both the program and data.

(c)   EDSAC – The EDSAC short for Electronic Delay Storage Automatic Computer was built by Prof. M.V. Wikes at Cambridge University in 1949 and used mercury delayed lines for storage. It also used Neumann concept ‘stored programs’. This allowed easy implementation of program loops

(d)  UNIVAC-I- Commercial production of strored program electronic computers began in the early 50’s. One such computer was UNIVAC-I built by Univac division of Remington Rand and Delivered in 1951. This computer also used vacuum tubes.

Though the first generation computers were welcomed by government and universities as they greatly helped them in these tasks, however, the first generation computers suffered from some big limitations like slow operating speed, restricted computing capacity, high power consumption, short mean time between failures. Further researchers in this line aimed at removal of these limitations.

2.     SECOND GENERATION COMPUTERS (1956-65)

A big revolution in electronics took place with the invention of transistors by Bardeen, Brattain and Shockley in 1946. Transistors were highly reliable compared to tubes. They occupied less space and required only 1/10 of power required by tubes. Also they took 1/10 time needed by tubes and were ten times cheaper than those using tubes.

Fig. 2. Second Generation Of  Computer

Another major event during this period was the invention of magnetic cores for storage. These are tiny ferrite rings (0.02 inch diameter) that can be magnetized in either clockwise or anti-clockwise direction. The two directions represents 0 and 1. Magnetic cores were used to construct large random access memories.

The second generation computers began with the advent of transistorized circuitry, invention of magnetic cores and development of magnetic disk storage devices. These new devlopments made these computers much more reliable.

 The increased reliability and availability of large memories saved the way for the development of high level language such as FORTRAN, COBOL, Algol and Snobol etc. With speedy CPU’s and the advent of magnetic tape and disk storage operating systems came into being. Batch operating systems ruled the second generation computers.

Commercial applications rapidly developed during this period and more than 80% of these computers were used in business and industries in the applications like payroll, inventory control, marketing, production planning etc.

Table of some second generation computers along with their area of application   

MODEL	SIZE	AREA OF APPLICATION
IBM 1401	Small to medium	business
IBM 1620	small	scientific
IBM 7094	large	Scientific and business
CDC 1604	Medium to large	scientific
CDC 3600	large	scientific
RCA 501	Medium	business
UNIVAC 1108	large	Scientific and business

THIRD GENERATION COMPUTERS (1966-75)

The third generation replaced transistors with Integrated Circuits called popularity as chips. The Integrated Circuit or I.C was invented by Jack Kilby at Texas instruments in 1958.

An I.C is wafer thin slice of extremely purified silicon crystals. A single I.C has many transistors, resisitors and capacitors along with the associated circuitry encapsulated in a small package with many leads.

Fig. 3. Third Generation Of Computer

The third generation computers using integrated circuits proved to be highly reliable, relatively inexpensive and faster. Less human labour was required at assembly stage. Examples of some main frame computers developed during this generation are : IBM-360 series, ICL-1900 series, IBM-370/168, Honeywell model 316

Some mini computers developed during this phase are:

ICL-2903 manufactured by international computers limited, CDC-1700 manufactured by control data corporation and PDP11/45.

Computers these days found place in other areas also like education, survey, small businesses, estimation analysis etc. along with their previous usage areas i.e. scientific and business.

FOURTH GENERATION COMPUTERS (1976-1985)

Fig. 4. Fourth Generation Of Computer

The advent of the microprocessor chip marked the beginning of the fourth generation computers medium scale integrated circuit yielded to large and very large scale integrated circuits packing about 50000 transistors in a chip. Semi conductor memories replaced magnetic core memories. The emergence of the microprocessor led to the emergence of extremely powerful personal computers. computer cost came down so rapidly that these found places in most offices and homes. The faster assessing and processing speeds and increased memory capacity helped in development of much more powerful operating systems.

The hard disk are also available of the sizes upto 80 GB. For larger disk RAID technology gives storage upto hundreds of GB. The CDROM are also becoming popular day by day. The CDROMs of today can store upto 650 MBs information.

FIFTH GENERATION COMPUTERS 

Fig. 5. Fifth Generation Of Computer

             

Fifth generation computing device based on artificial intelligence are still in development though there are some applications such as voice recognition that are being used today. The use of parallel processing and superconductors is helping to make artificial intelligence a reality. The goal of fifth generation computing is to develop  devices that respond to natural language input and are capable of learning and self organization.

Computers will have to be able to classify information search large databases rapidly, plan apply the rules which humans regard as clear thinking, make decisions and learn from their mistakes. Input devices for fifth generation computers could also include speech and visual recognition .

APPLICATION OF FIFTH GENERATION COMPUTERS

1.     Intelligent system that could control the route of a missile and defence system that could fend off attacks.

2.     Word processors that could be controlled by means of speech recognition.

3.     Programs that could translate documents from one language to another.