Evolution & History of Computer-2

In this part 2 of evolution and history of computer, we are going to learn about Mark-I,ABC,ENIAC,EDSAC,EDCVAC,UNIVAC and PDP computers.


Howard Aiken of Harvard University, in collaboration with engineers at IBM, undertook construction of a large automatic digital computer based on standard IBM electromechanical part called MARK-I in 1937. The Mark I became operational in 1944 and was used until 1959.


The Mark-I was officially known as the IBM Automatic Sequence Controlled Calculator (ASCC). This machine was complex in design and huge in size. It measured 51 ft long, 8 ft tall and 3 ft wide having 18000 vacuum tubes. It contained 7 lakhs 50 thousand parts and was strung with 500 miles of wires. It weighed approximately 32 tons.

This machine used instruction stored in paper tapes and punched cards, handling 23-decimal-place numbers (words) and could add or subtract two of these numbers in three-tenths of a second, multiply them in four seconds, and divide them in ten seconds.

Atanasoff-Berry Computer (ABC)

The earliest attempt to build an electronic computer was by John Vincent Atanasoff, a professor of physics and mathematics at lowa State College (now called lowa State University) in 1937.

Atanasoff-Berry Computer

Atanasoff set out to build a machine that would help his graduate students to solve systems of partial differential equations. Atanasoff teamed up with his graduate student, Clifford Berry, to build the first electronic computer. Their creation was termed the Atanasoff- Berry Computer, or nicknamed the ABC. This machine weighed 750 lbs. and had a memory storage of 3,000 bits (0.4K).

Electronic Numerical Integrator and Calculator (ENIAC)

Electronic Numerical Integrator and Calculator was the first electronic general purpose computer invented by John Mauchly and J.P.Eckert in 1946 at the Moore School of Electrical Engineering of University of Pennsylvania.

 ENIAC Computer

This machine was built to meet the needs of the US Armed Forces. It was 10 feet tall, occupied 1,000 square feet of floor-space, weighed in at approximately 30 tons, and used more than 70,000 resistors, 10,000 capacitors, 6,000 switches, and 18,000 vacuum tubes. The final machine required 150 kilowatts of power.

 ENIAC used a word of 10 decimal digits instead of binary digits. It could perform many complex arithmetic operations in less than a second. The ENIAC was designed to generate ballistic firing tables for the artillery, an extremely complex task.

Electronic Delay Storage Automatic Computer

Electronic Delay Storage Automatic Calculator (EDSAC) is an early British computer that is considered to be the first stored program electronic computer that was created at the University of Cambridge in England. The computer performed its first calculation on May 6, 1949 and was the computer that ran the first graphical computer game, nicknamed “Baby”. It was made by Maurice Wilkes and his team at the University of Cambridge Mathematical Laboratory in England.


EDSAC was the first stored-program electronic computer. It was also the first to run a computer game. Later the project was supported by J. Lyons & Co. Ltd., a British company. They were rewarded with the first commercial computer, LEO I. LEO I was based on the EDSAC design. EDSAC is used to calculate a table of square numbers and a list of prime numbers.

Electronic Discrete Variable Automatic


Electronic Discrete Variable Computer (EDVAC) was designed by John Mauchly and J.PEckert in 1952. It was the second stored program computer. It included a stored- program, a central processor and a memory for both data and programs. It contained approximately 4000 vacuum tubes and 10,000 crystal diodes when it was finally completed.

Universal Automatic Computer-l

UNIVAC-I (UNIVersal Automatic Computer I) was the second commercial computer produced in the United States. It was designed principally by J. Presper Eckert and John Mauchly. It was also based on the EDVAC design. It was 8 ft high, 15 feet long and weighed 5 tons.


It became operational at the Census Bureau in early 1951 for use in census taking. This computer consisted of magnetic tape for data input and output. The UNIVAC-I had an add time of 120 microseconds, multiply time of 1,800 microseconds, and divide time of 3,600 microseconds.

Programmed Data Processor-1


The PDP-1 (Programmed Data Processor-1) was the first computer in Digital Equipment Corporation’s PDP series and was first produced in 1959. It had five-megacycle circuits, a magnetic core memory, and fully parallel processing with a computation rate of 100,000 additions per second. It was also the original hardware for playing history’s first game on a minicomputer, Steve Russell’s Spacewar!

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