History of computers

By Anne Perera

Abacus•The first man-made computing device is the “Abacus”•The abacus, also called a counting frame.•The Chinese abacus was developed about 5000 years ago.•Addition, subtraction, division and multiplication can be performed on a standard abacus.

Slide Rule•John Napier, a Scotland national, found the Logarithms to the world in 1617.

•Using John Napiar’s logarithm concepts, the slide rule was designed in England in 1632.

Pascaline•Around 1642, a French mathematician called Blaise Pascal invented the adding machine that helped mathematical calculations.

•Additions and subtractions could be done easily by using it. •Pascal’s machine was one of the first mechanical calculating machine.

Difference Engine

•An Englishman called Charles Babbage designed the first model required for a mechanical computer in 1822.

Analytical Engine•Charles Babbage designed the 'Analytical Engine' in 1833.

•Components required for data input, storage, processing and output had been designed inside. •Computers designed later were greatly influenced by these concepts of Babbage and that is why Babbage is considered to be the ‘Father of computers’.

Ada Augusta Lovelace

•A friend of Babbage called Ada Augusta Lovelace was keen on preparing programmes required for his engine.

•Such programmes are considered to be the first attempt of computer programming.

•Ada Augusta Lovelace is considered to be the first computer programmer in the world.

•The computer language which was used later for military purposes was named Ada to pay respect for her.

Punch card•Herman Hollerith adopted the punched card concept.•Early method of data storage used with early computers.•Punch cards also known as Hollerith cards and IBM cards.

Computer classification

A computer can be classified as follows:

1)Based on the generations

2) Size

3) Purpose

4)Design technology / Computational method / Type

Based on generation

Generations of computers

1.First Generation Computers (1939-1958) – Vacuum tubes

First Generation Computers 1939-1958

•Based on Vacuum Tubes

•Used magnetic drums for main memory.

•Can solve one problem at a time.

•Input was based on punched cards and paper tape, and output was displayed on printouts.

•First generation computers based on machine language, the lowest-level programming language understood by computers

DisadvantagesVery large in size.

Consumed a large amount of energy.

They heated very soon due to thousands of vacuum tubes.

DisadvantagesThey were not very reliable.

Constant maintenance was required.

Very slow in speed.

Used magnetic drums which provide very less data storage.

ENIAC (Electronic Numerical Integrator and Computer) - world’s first electronic digital computer in 1946

UNIVAC (Universal Automatic Computer)- The first commercial computer

2. Second Generation Computers (1954-1959) – Transistors

Second Generation 1954-1959

•The second generation of computers used transistors for the internal operations.

•They used magnetic core for the memory

•Still based on punched cards for input and printouts for output.

•The first computers that stored their instructions in their memory, which moved from a magnetic drum to magnetic core technology.

•Used symbolic, or Assembly language, which allowed programmers to specify instructions in words.

•High-level programming languages were also being developed at this time, such as early versions of COBOL and FORTRAN.

Second Generation 1954-1959Advantages:

Smaller in size as compared to the first generation computers.

Computers were more reliable

Used less energy and were not heated.

Second Generation 1954-1959Advantages:Better portability as compared to the first generation computers.

Used faster peripherals like tape drives, magnetic disks, printers etc.

Used Assembly language instead of Machine language.

Accuracy improved.

Second Generation 1954-1959Disadvantages

Cooling system was required

Constant maintenance was required

Commercial production was difficult

Disadvantages

Only used for specific purposes

Expensive

Punch cards were used for input.

3. Third Generation Computers (1959-1971) – Integrated Circuits (IC)

Third Generation1959-1971•These computers used integrated circuits on silicon chips.

•A single IC chip may contain thousands of transistors.

Eg:- IBM 370, IBM System/360, UNIVAC 1108 and UNIVAC AC 9000

Third Generation1959-1971AdvantagesSmaller in size as compared to previous generations.More reliable.Used less energyProduced less heat as compared to the previous two generations.Better speed and could calculate data in nanoseconds.Used fan for heat discharge to prevent damage.

Third Generation1959-1971

AdvantagesTotally general purposeCould be used for high-level languages.Good storage capacity.Less expensiveBetter accuracyCommercial production increased.Used mouse and keyboard for input.

Disadvantages

Air conditioning was required.

High technology required for the manufacturing of IC chips.

4. Fourth Generation Computers (1971- Present) – Microchips Microprocessors

Fourth Generation 1971- Present

•Use microprocessor chips.

•The Microprocessor contains thousands of ICs.

•The technology of integrated circuits improved rapidly. •The LSI (Large Scale Integration) circuit and VLSI (Very Large Scale Integration) circuit was designed.

•Reduced the size of computer.

•The size of modern Microprocessors is usually one square inch.

•It can contain millions of electronic circuits.

•Examples :- Apple Macintosh & IBM PC.

•Can be linked together to form networks, which led to the development of the Internet.

• Introduced GUI’s and hand-held devices.

Fourth Generation 1971- PresentAdvantagesMore powerful and reliable than previous generations.

Small in size

Fast processing power with less power consumption

Fan for heat discharging and to keep cold.

Totally general purpose

AdvantagesCommercial production

Less need of repair.

Cheapest among all generations

All types of High level languages can be used in this type of computers

5. Fifth Generation computers (Present - Beyond) – Artificial Intelligence (AI)

Fifth Generation computers (Present - Beyond)

•Based on the technique of Artificial Intelligence (AI).

•Computers can understand spoken words & imitate the human.

•Can respond to its surroundings using different types of sensors.

Fifth Generation computers (Present - Beyond)

•Scientists are constantly working to increase the processing power of computers.

•IBM Watson computer is one example for a 5th generation computer.

•There are some applications, such as voice recognition, that are being used today.

Based on size

Computers can be classified according to their sizes too. Mainframe computers

Mini computers

Micro computers

Based on size There are different types of Micro computers. Some of them are,

• Personal Computers (PC)

• Laptop Computers

• Palmtop computers

• Workstations

• Server computers

• Super computers

Based on the purposeComputers can be categorized into two types based on their purpose.

1)General Purpose ComputersComputers used for usual and day - to - day

activities.

2) Special Purpose ComputersComputers used for special purposes such as scientific experiments, air traffic control systems etc.

Based on their design technology

1) Digital computers

Computers designed by using the binary /digital number system are called digital computers.

A digital computer can count and accept numbers and letters through various input devices.

2) Analog computers

Computers which are designed considering the physical data such as temperature, sound, and pressure etc.

Analog computers process data input in a continuous form.

2) Analog computers

Data such as voltage, temperature are represented in the computer as a continuous, unbroken flow of information.

Analog computers are used in engineering and scientific applications.

3) Hybrid computers

A combination of the above two types of computers.

Example: In Process Control Computer Systems, the inputs comes from devices like pressure, thermometers etc.

3) Hybrid computers

The inputs from analog devices are sent to a digital computation unit that runs the mathematical model for controlling the process.

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