History Generations & Classification of Computers

History Generations & Classification of Computers

History of Computer:

The discovered of numbers, which is considered as the greatest achievement of making led to the development of all kinds of calculating devices. Today we can’t imagine a work without numbers. It took thousands of years to get the present system of numbers. Its development passed through several stages.

— The Stone Age (पाषाण युग) man used pebbles (कंकड़) for counting people or animals.

— Stone was replaced by sticks on a rope (रस्सी).

— All these computing techniques required some physical effort from man.

— A lot of work was required for large calculations and the process was very slow.

— Later these scratches and symbols were replaced by the present number system. Number system found its use in astronomy, building temples & churches and calculating areas.

— The discovery of zero by Indian mathematician laid the foundation stone for numeric system.

THE ABACUS:

The earliest and the simplest device that was used for calculations was the Abacus. Simple Abacus has been in used since 3000 B.C. Abacus was first developed in China and later its use spread to all parts of the world. Even today, it is still used in many countries in far-east. It was the first device to introduce the concept of data-storage.

Abacus is a clay board with number of beads that are placed on roads (or) wires. The beads are moved from one side to another for counting.

NAIPERS LOGS AND BONES:

The next manual calculating device logarithms was invented by John Napier in (1550-1617). The use of logarithms enabled him to transform multiplication and division problems into problems of addition and subtraction. The word logarithms is a combination of two Greek words, loges (means ratios) and arithms (means numbers).

PASCAL'S ADDING MACHINE:

The first mechanical adding machine was invented by Blaise Pascal in 1642. He developed it to help his father who was a tax officer in France. The second machine was a more effective calculator produced by Gottfried Leibnitz in 1684 which performed multiplication and division.

CHARLES BABBAGE:

Charles Babbage, a nineteenth century professor at Cambridge University is considered to be the father of modern digital computer. He designed his "Differential Engine" in 1822 and his "Analytical Engine “ in 1833 which was designed later, is generally recognized as the milestone signifying the start of the computer age.

HOLLERITH'S MACHINE:

In 1885, Herman Hollerith, a census statistician with U.S. Census Bureau, developed a machine run on electricity for the first time for calculating and recording data. Hollerith's machine was capable of reading both numbers and letters, processing and giving out letters and numbers in the desired form. The input was in the form of punched cards and the combinations of holes. He invented a machine that punched holes on cards which was called 'Tabulator'.

This machine solved the information of 60 million people of 1890 U.S. census just in three years. In 1896, Hollerith established his own company called Tabulating Machine Company (TMC). The same company is today known as "INTERNATIONAL BUSINESS MACHINES" (IBM). This research in computers which has been going on for years is generally described as series of Generations.

GENERATIONS OF COMPUTER:

The term "generation" refers to major development in electronic data processing. 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. It has been in five distinct stages. Each of these stages is called a Generation. There are five generations:

The development of this device led to the formation of generation which can be classified as under :

Generation

Year

Components used

Memory

Speed (in thousand)

1st Generation

1946-55

Vacuum Tubes

20 KB

30 Instructions per second (IPS)

2nd Generation

1956-65

Transistors

128 KB

300 IPS

3rd Generation

1966-75

Integrated Circuits (IC Chip) with SSI & MSI Technology

1 MB

1 KIPS

(1*10 IPS)

4th Generation

1976-85

Micro Processor with LSI & VLSI technology

16 MB

8 Mips (1*10 IPS)

5th Generation

1986- till date

Micro processor with ULSI Technolgy

152 MB

20 logical instructions Per second (LIPS)

ADVANTAGES AND DISADVANTAGES OF EACH GENERATION

Generation

Advantages

Disadvantages

1st Generation

Vacuum Tubes made possible the designing of digital computers.

Too bulky in size, too much heat generated, limited use.

2nd Generation

Smaller in size, Faster Processing.

Frequent maintenance required, expensive.

3rd Generation

Smaller in size, Low maintenance cost, More Fast, More compact.

Air Conditioning required in most cases, highly advanced technology required to; IC Chips.

4th Generation

Smaller in size, Faster in computation cheapest among all, minimum maintenance required, and used totally for general purpose.

Highly sophisticated technology required for the LSI and VLSI Chips.

5th Generation

Very small in size, Very fast in computation, cheap, minimum maintenance required and used for general purpose or special purpose.

Very highly sophisticated technology required for the VLSI chips.

CLASSIFICATION OF COMPUTER:

Computers, that is more reliable (विश्वसनीय) but a bit confusing to new comers. To give the to detail in most brief manner, important topics are given as under.

        Computers can be classified broadly into three categories:

• Digital

• Analog

• Hybrid

DIGITAL:

These computers converts the data into digits and then counts the numbers (or digits) that represents numbers, letters or other special symbols. Mostly these computers are used for business and scientific purpose. Ex : PC (Personal Computer), PC-XT (Extended Technology), PC-AT (Advanced Technology) etc.

ANALOG:

A computer designed to respond (प्रतिक्रिया) to an infinite number of variations and signals. It operates by measuring (मापना) rather than counting. These computers are used mostly in Engineering and Scientific calculations. Ex : Thermometer, Speedometer etc.

CLASSIFICATION OF DIGITAL COMPUTERS :

When people speak about computers, they mean only digital computers and we also will be dealing only about digital Computers. Digital computers can be classified according to their purpose and size.

The speed of a computer can be measured in milli seconds, micro seconds, nano seconds and Pico seconds.

Milli-Seconds - One thousand of second

Micro-Seconds - 1 Millionth of a second (Ms)

Nano-Seconds - 1000 Millionth of a second (Ns)

Pico-Seconds - 1000 x 1000 millionth of a Second

Classified according to purpose, Computers are of two types computers:

Special Purpose computers:

A special purpose computer is designed to perform only one specific task. The program or instructions set is permanently stored in such a machine, although it lacks versatility, it does its single task quickly and efficiently.

General Purpose Computers:

A general purpose computer is the one which has the capability of storing different programs and can thus be used in numerous applications.

Classified according to size, Computers are of four types:

1. Super Computers:
   

These are basically designed for complex scientific application processing needs. The processing speed of this computer is very high compared to Mini and Micro. The speed is measured in Pico seconds. It is a multi-user system. It is six times faster than largest mainframe computer. These are very large and very expensive too. The storage capacity of these computers is in the range between 64 MB to 4 GB. The word length is from 64 to 128 bits. High speed laser printers, disks, tapes etc., are used as peripherals.

  Examples : CRAY, CRAY-2, NEX SX-2.

The best example of Super Computer's creation is ROBOT.

1. Mainframe Computers:

These are also multiuser systems. They are generally used in a centralized computer centre, Different departments will be having different terminals and these are connected to the mainframe computers. Mainframe computers provide large storage capacity and faster C.P.U. speed. It is not based on single chip processor, several Math and Logic Processor's are used. Its speed is measured in nano-seconds. A maximum of 200 users can work at a time. A few application areas where these computers are mostly used are for engineering designs, line application with large data base etc.,

Examples : DEC 1090, Cyber 170,IBM-3601370,IBM 1390, UNIVAC 1100160, IBM 4300 Series.

1. Mini Computers:

It is also a multiuser system. It allows 50 users to work at time. The storage capacity ranges from 2 MB to 16 MB. The minicomputer offers the advantage of a Mainframe computer at lower costs. The first popular minicomputer was named as PDP-8, which was launched in 1965. It is used mainly for railway reservations and banking.

Examples : PDP•8, PDP-II, VAX-7500, HCL-Daysis.

1. Micro Computers:
   

These types of computers are called as personal computers as it is a single user system, i.e., only a single person can work at a time. These computers are very popular in the market because of its low rate. Micro computers use Micro Processor i.e, a single chip that contains a processor, register and a control unit. The speed of the CPU is only about 100 KIPS (Kilo instructions per second). The maximum word length ranges from 8, 16,32 bit. The number of peripherals attached to these computer are very few.