•  History of Computer

Fist Generation (1946-1954): In 1946 the digital computer using electronic valves (Vacuum tubes) are known as first generation computers. The first "computer" to use electronic valves i.e. vacuum tubes. The high cost of vacuum tubes prevented their use for main memory. They stored information in the form of propagating sound waves.

The vacuum tube consumes a lot of power. These computers were large in size and writing programs on them was difficult. Some of the computers of this generation were:

ENIAC: It was the first electronic computer built in 1946 at University of Pennsylvania, USA by  John Eckert and John Mauchy. It was named Electronic Numerical Integrator and calculator 30 tons, contained 18000 vacuum tubes, 70,000 resisters, 10,000 capacitors and required 15,000 watts of electricity. Today computers is many times as powerful as ENIAC, still size is very small.

EDVAC: It stands of Electronic Discrete Variable Automatic Computer and was developed in 1950. The concept of storing data and instructions inside the computer was introduced here, This allowed much faster operation since the computer had rapid access to both data and instructions. The other advantage of storing instruction was that computer could do logical decision internally. The EDVAC was a binary serial computer with automatic addition, subtraction, multiplication, programmed division and automatic checking with an ultrasonic serial memory.

EDSAC : It stands for Electronic Delay Storage Automatic Computer and was developed by M. V. Wilkes at Cambridge University in 1949. The EDSAC performed computations in the three millisecond range. It performed arithmetic and logical operations without human intervention. They key to the success was in the stored instructions which depended upon solely for its operation.

 This  machine marked the beginning of the computer age.

UNIVAC-1: It stands for University Automatic Computer

and it was the First commercial computer developed by United States In 1951. The machine was 2 feet by 50 feet in length, contained, 5,600 tubes, 18,000 crystal diodes, and 300 relays. It utilized serial circuitry, 2.25 MHz bit rate, and an internal storage capacity 1,000 words or 12,000 characters.

The UNIVAC was used for general purpose computing with large amounts of input and output. The UNIVAC was also the first computer to come equipped with a magnetic tape unit and was the first computer to use buffer memory.

Limitations of First Generation Computer 

• Following are the major drawbacks or First Generation computers.
• They used the major drawbacks of First generation computer.
• They used valves or vacuum tubes as their main electronic componet.
• They were large in size, slow in processing and had less storage capacity.
• They consumed lots of electricity and produced lots of heat.
• Their computing capabilities were limited.
• They were not so accurate and reliable.
• They used machine level language for programming.
• They were very expensive

Second Generation (1955-1964) : The second-generation computer used transistors for CPU components and ferrite cores for main memory & magnetic disks for secondary memory. They used high-level languages such as FORTRAN (1956), ALGOL (1960) & COBOL (1960-1961). Input Output (I/O) processor was included to control I/O operations.

Manufacturing cost was also very low. Thus the size of the computer got reduced considerably.

It in the second generation that the concept of Central Processing Unit (CPU), memory, programming language and input and output units were developed. Some of the second generation computers are IBM 1620, IBM 1401, CDC 3600.

Features : 

• Transistors were used instead of Vacuum Tube.
• Processing speed is faster than First Generation Computer (Micro Second)
• Smaller in Size (51 square feet)
• The input and output devices were faster.

Third Generation (1964-1977) : 

By the development of a Small chip consisting of the capacity of  the 300 transistors. These Integrated Circuits (IC)s are popularly known as A single IC has many transistors, registers and capacitors built on a single thin slice of silicon. So it is quite obvious built on a single thin slice of silicon. So it is quite obvious that the size of the computer go further reduced. Some of the computers developed during this period were IBM-360, ICL -1900, IBM-370, and VAX -750. Higher level language such as BASIC (Beginners All purpose Symbolic Instruction Code) was developed during this period.

Computers of this generation were small in size, low cost, large memory and processing speed is very high. Very soon ICS were replaced by LSI (Large Scale Integration), which consisted about 100 components. 

Features :

• They used Integrated Circuit (IC) chips in place of the transistors.
• Semi conductor memory devices were used.
• The size was greatly reduced, the  speed of processing was high, and they were more accurate and reliable.
• Large Scale Integration (LSI) and very Large scale integration (VLSI) were also developed.
• Then mini computers were introduced in this generation.
• They used high level language for programming.

Fourth Generation (1978-present) :

An IC containing about 100 components is called LSI (Large Scale Integration) and the one, which has more than 1000 such components, is called as VLSI ( Very Large Scale Integration)

It uses scale Integrated Circuits (LSIC) built on a single silicon chip called microprocessors. Due to the development of microprocessor it is possible to place computer's centralprocessing unit (CPU) on single chip These computers are called microcomputers.

Later very large scale Integrated Circuits (VLSIC) replaced LSICs. Thus the computer which was occupying a very large room in earlier days can now be placed on a table .The personal computer (PC) that you see in you see in your school is a Fourth Generation Computer Main memory used fast semiconductors chips up to 4 M bits size. Some of the Fourth generation computers are IBM PC, Apple Macintosh, etc.

Features :

• They used Microprocessor (VLSI) as their main switching element.
• They are also called as micro computers or personal computer.
• Their size varies from desktop to laptop or palmtop.

Fifth Generation (PRESENT AND FUTURE) :

5th generation computer use ULSI (Ultra - Large Scale Integration) Chips. Millions of transistors are placed in a single IC in ULSI chip.

64 bit microprocessors have been developed during this period. Memory chips and flash memory up to 1 GB, hard disks up to 600GB & optical disks up 50 GB  have been developed.

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.

Artificial Intelligence is the branch of computer science concerned with making computers bahave like humans. The term was coined in 1956 by john McCarthy at the Massachusetts Institute of Technology. Artificial intelligence

Games Playing:  Programming computers to play games such as chess and checkers

Expert System: Programming computers to make decision in real-life situations (for example, some expert systems help doctors diagnose diseases based on symptoms)

Natural Language: Programming computers to understand natural human language.

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@adiksha bhagat.