#### 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.

**Mark-I**

**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 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.

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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