Development of computer: Generations and classification of computers

Development of computer

Computer is a man-made electronic machine that changes the way we work, live, and play. A machine that has done all this and more, now exists in nearly every business and one out of every two households. This incredible invention is the computer.

The computer is one of the most powerful innovations in human history. The electronic computer has been around for over a half-century, but its ancestor abacus has been around for 2000 years.

However, only in the last 40 years it has changed the our lifestyle. From the first wooden abacus to the latest high-speed microprocessor, the computer has changed nearly every aspect of people’s lives for the better. With the use of computers, people are suddenly able to perform a large amount of computations at dazzling speed. Information can be crunched, organized, and displayed in the blink of an eye. Things that were only dreams a few years ago are now possible due to computers.

  1. Evolution of Computers
  2. Computer Generations
  3. Classification of Computers
  4. Classification By Size And Shapes

Development of computer from Abacus to Microsoft Surface

Evolution of computers

Development Approximate Date Important Feature
Abacus 3000-1000 B.C. First mechanical calculator.
Pascal’s Calculator 1645 First adding machine capable of counting, adding and subtracting.
Jacquard’s weaving loom 1801 Utilized metal plates with punched holes to control weaving patterns.
Babbage Analytical Engine 1834-1871 Intended to be the First general purpose computer. The engine was never constructed in Babbage’s lifetime.
Herman Tabulating Machine 1887-1896 Designed a code and device to punch data into card and tabulate collected data. Used in automating the Census of 1980.
Howard Aiken Mark I 1937-1944 The largest electro-mechanical computer ever built. Utilized punch paper tape to store data.
ENIAK 1943-1950 First electronic computing devices in which program wired into a permanent panel. No significant storage capability.
John Von Neumann’s Stored Program Concept 1945-1952 Developed the concept of storing program instructions and data in the memory of the computer. Credited with introducing the idea of coding data and instructions in binary.
EDSAC 1946-1952 First computer capable of storing instructions and data in memory.
UNIVAC 1 1951-1954 First computer that was commercially available and produced in quantity.

1. Abacus

Abacus: First Calculator

The abacus is one of the earliest known computation devices. It is a tool that helped in calculating answers of arithmetic problems. It is simply a wooden rack holding parallel wires on which beads are strung. Calculations are done by manipulating the beads. The abacus was developed in China about 5000 years ago. The abacus was so successful that its use spread form China to many other Countries.

2. Pascal calculator

Pascal Computer

The first real mechanical calculator was invented by a French scientist and mathematician Blaise Pascal, around 1645. The device was constructed by interlocking gears representing the number 0 to 9. It was only able to do addition and subtraction, so it is called adding machine.

3. Analytical Engine

Analytical Engine

In 1801, Joseph Marie Jacquard perfected the idea of the automated weaving loom. Using holes punched into a series of connected cards, Jacquard was able to control the weaving of fabrics. The Jacquard loom not only cut back on the amount of human labor, but also allowed for patterns to be stored now on cards and to be utilized over and over again to achieve the same product.

In 1820 Charles Babbage, a British mathematician and inventor, designed and built the mechanical calculator and the Difference Engine on principles that anticipated the modern electronic computer. The concept Babbage put forward was eventually used by engineers in the development of the first computer prototype. For this reason Charles Babbage is known as father of computing.

Despite ten years of work, Babbage failed to built a fully operational model of Difference or Analytical Engine. In 1842 Lady Lovelace wrote a demonstration program and her contribution to binary arithmetic was later used by John Von Neumann in developing the modern computer. So she (Lady Lovelace) is often regarded as the “first computer programmer“.

4. Herman Hollerith and Punch cards

Herman Hollerith and Punch cards: IBM

In 1890 the United States Census Bureau asked Herman Hollerith to find a way to speed up the processing a census data. Herman Hollerith created punch cards that resemble today’s computers cards. He also invented Hollerith-80 column code and tabulating machine.

5. First Electronic Computer: ENIAC

Howard Aiken, with his colleagues at Harvard and with some assistance from International Business Machines he had built by 1942 the Mark 1, the world’s first program-controlled calculator, an early form of a digital computer.

First Electronic Computer: ENIAC

In 1944 John Mauchley, an American physicist, and J. Presper Eckert, an American engineer, proposed an electronic digital computer, called the Electronic Numerical Integrator And Computer (ENIAC), and completed it in 1946 which is regarded as the first successful general digital computer.

6. Stored Program concept: EDSAC

According to John Von Neumann‘s concept, the operating instructions and data used in processing should be stored inside the computer. Whenever necessary the computer would have the capability to modify these program instructions, during their execution.

This concept was incorporated into the EDSAC computer (Electronic Delay Storage Automatic Computer), which was developed at Cambridge University. This computer was capable of storing a sequence of instructions, the equivalent of the first computer program.



It is the short form of Universal Automatic Computer. In 1951 it was introduced and became the first commercially available computer. The UNIVAC 1 was characteristic of the first generation of computers.

Computer Generation

The history of the development of computer is often referred to in tracing the different generations of computing devices. Each generation of computer is characterized by a major technological development that fundamentally changed the way computers operate, resulting in increasingly smaller, cheaper, more powerful and efficient and reliable devices.

Generation Characteristics
First Generation 1. Use of vacuum tubes in circuits.

2. Use of magnetic drum as primary internal storage medium.

3. Limited main storage capacity.

4. Slow input/output.

5. Low-level symbolic language programming

6. Heat and maintenance problem.

Applications: Payroll processing and record keeping

Example: ENIAC, IBM 650, UNIVAC 1

Second Generation 1. Use of transistors at the place of vacuum tubes.

2. Use of magnetic core as primary internal storage medium.

3. Increased main storage capacity.

4. Faster input/ output.

5. Great reduction in size and heat generation.

6. Increased speed and reliability.

7. High level programming language (COBOL and FORTRAN).

Applications: Batch oriented (Billing, Payroll processing and Updating inventory files.

Example: IBM 1401, Honeywell 200, CDC 1604.

Third Generation 1. Use of IC (Integrated circuit).

2. Use of magnetic core as primary storage medium.

3. More flexible input/ output.

4. Smaller size, better performance and reliability.

5. Increased speed and better performance.

6. Extensive use of high level programming languages.

7. Emergence of minicomputers. Remote processing and time sharing through communication.

8. Availability of operating system software to control input/output.

Applications: Airline reservation system, market forecasting and credit card billing.

Example: 1BM System/360, NCR 395, Burroughs B6500.

Fourth Generation 1. Use of large scale integrated circuit.

2. Increased storage capacity and speed.

3. Modular design and compatibility between hardware provided by different manufacturers.

4. Greater versatility of Input/output devices.

5. Introduction of microprocessors and microcomputers.

6. Increased use of microcomputers.

Applications: Electronic fund transfer, computer-aided instruction, home computers and mathematical modeling and simulation.

Example: BM PC-XT (microcomputer), Honeywell 6080 series., Apple II.

First Generation (1942-1955)

The first generation computers were entirely electronic. They used vacuum tubes to store instructions. Magnetic drums were used for memory. They were often enormous, taking up entire rooms. They were very expensive to operate and, in addition to using a great deal of electricity, generated a lot of heat which often needed expansive air-conditioning.


First generation computers relied on machine language (1s and 0s), the lowest-level programming language understood by computers, to perform operations, and they could solve only one problem at a time.

The UNIVAC 1, ENIAC and Mark 1 computers are examples of the first-generation computing devices. The UNIVAC was the first commercial electronic computer. This machine was developed specially for scientific and military purposes but it was dedicated to a business client, the U.S. Census Bureau in 1951.

Second Generation (1955-1964)

In second generation of computers solid state transistors replaced vacuum tubes in computers. It was invented in Bell Laboratories. The transistor was far superior than the vacuum tube, allowing computers to become smaller, taster, cheaper, more energy-efficient and more reliable. To represent data a magnetic core is used in computer. At about the same time magnetic tape and disks began to be widely used as an auxiliary storage. Magnetic disk was layered by iron oxide. Magnetic disks made possible direct access of data.

SECOND Generation Computers 1955-1964

As a result of these developments, a significant increase in the speed and processing capability of computers was achieved. Businessmen began to use computers in increasing numbers and new high-level programming languages also developed at this time, such as early versions of COBOL and FORTRAN.

Third Generation (1965-1974)

Further development in electronics brought further reduction in size, greater reliability, speed and lower costs computer. Integrated circuits (IC) replaced the transistors, which was developed by J.S.Kilbi. This was the hallmark of the third generation of computers.


This development is known as LSI (Large Scale Integration) and it refers to the ability to compress large number of integrated circuits on a single silicon chip.

There is also VLSI (Very Large Scale Integration). Another development that changed the way people use computers was time sharing. A time-shared computer allows many users, each working at a separate input/ output terminal, to use it at the same time.

Users interacted with third generation computers through keyboards and monitors and interfaced with an operating system, which allowed the device to run many different applications at one time with a central program that monitored the memory.

Computers for the first time became accessible to mass users because they were smaller and cheaper than their predecessors. Users could use software according to their need because Software and hardware were available separately.

Fourth Generation (1975- Up till now)

Fourth Generation computer continued to be characterized by chips that can contain increasing numbers of items. This further miniaturization of components, referred to as ULSI(Ultra Large Scale Integration), resulted in increased speed, greater reliability, and enormous storage capacities for current computers.


By using LSI technology. microprocessor was produced. This microprocessor brought the fourth generation of computers, as thousands of integrated circuits were built onto a single silicon chip. Computer of the first generation that filled an entire room could now fit in the palm of the hand.

The Intel 4004 chip, developed in 1971, located all the components of the computer from the CPU and memory to input/output controls on a single chip.

In 1981 IBM introduced its first computer for the home user, and in 1984 Apple introduced the Macintosh.

Microprocessors also moved out of the realm of desktop computers and into many areas of life. Everyday products such as vehicles, microwave oven and electronic games etc. began to use microprocessors more and more.

As these small computers became more powerful, they could be linked together to form a network, which eventually led to the development of the Internet. Fourth generation computers also saw the development of GUIIs, the mouse and handhold devices.

Fifth Generation (Present and Beyond)

Unlike all other generation computers, present generation of computers characterized by the use of the technique used to reduce complex Programming. This technique is known as Artificial intelligence (AI).

Fifth generation computing devices, based on artificial intelligence, are still in development, though there are some applications, such as voice recognition, that are being used today.

Classification of computer by the purpose which they design

1. Special Purpose Computers

The special purpose computers are used to solve a single and dedicated type of problem. For their specialized use, they are extremely efficient and economical. Example- automatic aircraft landing, computerized traffic control systems.

2. General Purpose Computers

The general purpose computers are flexible and versatile. They can be used to solve a variety of problems by changing the program or instructions. Example- Accounting, Simulation and forecasting.

Classification of computer by the types of data which they are capable of manipulating

1. Digital computer

In digital computers data are represented as discrete units or electrical pulse, which can be counted and switched. In modern digital computer binary system is used. Digital clock is its good example Due to fast speed and large storage capacity digital computers are used for business and scientific data processing.

2. Analog computer

In analog computers data are represented as physical quantities. Physical quantities are best measured in a continuous fashion and thus are ideally suited for analog computation. Analog computer is a machine that works on data which is always changeable. Analog form of electricity is used by us. Speed of this kind of computers are slow. Voltmeter, thermometer and barometer are the examples of analog device. Analog computers are most often used for scientific and engineering purposes.

3. Hybrid computer

Hybrid computers have combined features of both digital and analog computers with the input and output in analog form and the processing in digital form. This involves analog to digital converter at the input end and digital to analog converter at the output end.

Classification of computer by the types of data: Hybrid computer

Classification of computers on the basis of Price, Size and Capabilities

1. Super Computers

Supercomputers are the most powerful computers as of now. These computers are large in size and memory compared to all other computers. They work with multi-processing and parallel processing facilities.

At present, specially in computing speed, these are very fast. So, these are the fastest, biggest and most expansive computers. These machines are special high capacity computers used by very large organizations. They contain thousands of microprocessors.

First super computer of world was CRAY-1 which was developed by Cray research company in 1976.

First super computer of India was PARAM which was developed by C-DAC in 1991. It was designed for ultra high performance task such as creating animation, weather forecasting, nuclear energy research, encryption cracking and designing.

Examples are CRAY-1 and IBM’s Deep Blue.

2. Mainframe Computer

Mainframes are characterized by large internal memory storage and comprehensive range of software and peripheral equipment that might be connected. Mainframe computers occupy specially wired, air-conditioned rooms. Although not nearly as powerful as supercomputers, mainframe computers are capable of great processing speeds and data storage.

Mainframe Computer IBM

In these computers processing capacity and speed are very fast and more than one user works at a time. Multics was a mainframe time sharing operating system which was developed at Bell Laboratories. A typical super computer the CRAY-1 costs about $20 million. These computers are used in scientific and business application. For example, insurance companies use mainframes to process information about millions of policy holders.

Examples are IBM-370, IBM-S/390, DEC VAX 8800 and UNIVAC – 1110.

3. Mini Computer

Minicomputers are smaller in size, faster, cost lower than mainframes and higher than Personal Computer. They are designed for real time dedicated multi user application. Minicomputer converts into super minicomputer by using the 80386 super chip.


Super minicomputer processes 5 lac process per second. These computers are used in company, passenger reservation and research etc.

Examples are IBM-17, DEC PDP 11, HP- 9000, AS 400 and BULL HN- DPX2.

4. Micro Computer

Microcomputers are computers whose central processing unit consists of a microprocessor. A microprocessor is an integrated circuit. Microcomputers are the least powerful, yet the most widely used and fastest growing type of computers.

There are four types of microcomputer : desktop, notebook, tablet PC and handheld computers.

Desktop computers are small enough to fit on top of or alongside a desk yet are too big to carry around.

Notebook computers, also known as laptop computers, are portable, lightweight, and fit into most briefcases.

A tablet PC is a type of notebook computer that accepts your handwriting. This input is digitized and converted to standard text that can be further processed by programs such as a word processor.

Handheld computers are the smallest and are designed to fit into the palm of one hand. Also known as palm computers.

Hardware for a microcomputer system consists of a variety of different devices such as system unit, input/output, secondary storage, and communication. The main media of input into a microcomputers a a keyboard and a mouse and output is the monitor.

The processing speed of microcomputer is 1 lac process per second. These computers are used for business application, entertainment, at home and the field of medicine.

Examples are APPLE MAC, I Mac, IBM PS/2, IBM compatible and PS 386, 486.

5. Personal Computer

A small, relatively inexpensive computer designed for an individual user. It is based on the microprocessor technology that enables manufacturers to put an entire CPU on one chip.

Personal Computer

Businesses use personal computers for word processing, accounting, desktop publishing and for spreadsheet and database management application. At home, the most popular use of personal computers is for playing games, email, chatting etc.

Examples are Apple II, IBM PC, Lenovo and HP etc.

6. Laptop

A laptop is a personal computer designed for mobile use. It is small enough to sit on one’s lap and fits in to a briefcase. It integrates most of the components of a desktop computer, including a monitor, a keyboard, a pointing device (also known as a track pad), speakers, and other drives.

It includes rechargeable battery, so it works anywhere. By using blue-tooth and wi-fi we can access the Internet.

7. Notebook Computer

An extremely lightweight personal computer. It is generally thinner and smaller than laptop.

Notebook: Microsoft Surface

8. Workstations

Workstations are special single user computers having the same features as personal computer but have the processing speed equivalent to minicomputer or mainframe computer. A workstation computer can be fitted on a desktop. Scientists, engineers, architects and graphic designers mostly use these computers.

Workstation computers are expensive and powerful computers. These have advanced processor, more RAM and storage capacity than personal computers. These are usually used as single-user application but are used as servers on computer network and web servers as well.

9. Palmtop

A small computer that literally fits in our palm. Compared to full-size computers, palmtops are severely limited, but they are practical for certain functions such as phone books and calendars. Palmtops that use a pen rather than a keyboard for input. Because of their small size, most palmtop computers do not include disk drives.

However, many contain PCMCIA (Personal Computer Memory Card International Association) slots in which we can insert disk drives, modems, memory and other devices.

Palmtops are also called PDAs, hand-held computers and pocket computers. Example: Modern Tablets.

Development of computer: Evolution of Computers, Computer Generations and Classification of Computers

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