Early development of computers

Early development of computers is divided into two part

Electromechanical computers.

Electronic Computers

Under electromechanical computers:

Mark-I : In 1937, Howard Aiken developed first elect mechanical computer Mark-I. It is also called first computer. It was also based on the principle of Charles Babbage. It was huge in size (51ft*81ft*3ft), consumed a lot of electricity, generated high heat. It was milestone in the history o f the computers. It contained 18000 vacuum tubes (valves) and weighed 32 tonnes approximately. Again, he modified his computer and called Mark-II computer in 1944. This computer contained 19000 vacuum tubes as well.

ABC: Atanasoff Berry Computer computer was invented by J.V. Atanasoff and his student Clifford Berry in 1937 to 1942 A.D. It used 18,000 valves & 45 valves for internal logic and capacitors for storage of electrical charge. It used punched cards as secondary storage media.

Under Electronic Computer

ENIAC (Electronic Numerical Integrator And Calculator)

EDVAC (Electronic Discrete Variable Automatic Computer)

EDSAC ( Electronic Delay Storage Automatic computer)

UNIVAC (UNIVersal Automatic Computer)

ENIAC: Dr. John W. Mauchly & J. Presper Eckert developed ENIAC at Moore school of Electrical Engineering of the University of Pennsylvania in 1946 and was the first electronic computer. This had no moving parts except the input and output devices. It was developed for military purposes and was used for many years to solve ballistic problems. The addition of two numbers was achieved in 200 microseconds and multiplication in 2000 microseconds. It occupied the room measuring 9m*15m and contained 17,468 vacuum tubes, more than 70,000 registers, 10,000 capacitors, 60,000 switches and weighed 30tonnes.the ENIAC performed 5000 additions per second and consumed 150KV of electric power. Programs were coded into the machine by a system of changing wired plug boards and using the series of manual switches.

Drawbacks:

Its programs were wired plug on boards which made difficult to change programs. Cooling problem because of high heat generated by vacuum tubes.

EDVAC: Between 1946 and 1950, John Von Neumann, the Hungarian mathematician developed a computer called EDVAC. Neumann was the first to introduce the stored program concept in computer. The storage capacity of was 1024c words of 44-bits. It also had a auxiliary storage of 20,000 words. The access time of primary storage varied between 0.48 to 384.0 microseconds.

EDSAC (Electronic Delay Storage Automatic Calculator) was an early British computer (one of the first computers to be created). The machine, having been inspired by John von Neumann's seminal EDVAC report, was constructed by Professor Sir Maurice Wilkes and his team at the University of Cambridge Mathematical Laboratory in England.

EDSAC : EDSAC was the world's first practical stored program electronic computer, althougnot the first stored program computer (that honor goes to the Small-Scale Experimental Machine).The project was supported by J. Lyons & Co. Ltd., a British firm, who were rewarded with the first commercially applied computer, LEO I, based on the EDSAC design. EDSAC ran its first programs on May 6, 1949, calculating a table of squares and a list of prime numbers.

As soon as EDSAC was constructed, it began serving the University's research needs. None of its components were experimental. It used mercury delay lines for memory, and derated vacuum tubes for logic. Input was via 5-hole punched tape and output was via a teleprinter.

Initially, registers were limited to an accumulator and a multiplier register. In 1953, David Wheeler, returning from a stay at the University of Illinois, designed an index register as an extension to the original EDSAC hardware.

UNIVAC: The UNIVAC I (UNIVersal Automatic Computer I) was the first commercial computer produced in the United States. It was designed principally by J. Presper Eckert and John Mauchly, the inventors of the ENIAC. Design work was begun by their company, Eckert-Mauchly Computer Corporation, and was completed after the company had been acquired by Remington Rand. (In the years before successor models of the UNIVAC I appeared, the machine was simply known as "the UNIVAC".)The first UNIVAC was delivered to the United States Census Bureau on March 31, 1951, and was dedicated on June 14 that year. The fifth machine (built for the U.S. Atomic Energy Commission) was used by CBS to predict the result of the 1952 presidential election. With a sample of just 1% of the voting population it correctly predicted that Dwight Eisenhower would win. The UNIVAC I computers were built by Remington Rand's UNIVAC division (successor of the Eckert-Mauchly Computer Corporation, bought by Rand in 1950).

Major physical features

UNIVAC I used 5,200 vacuum tubes, weighed 29,000 pounds (13 metric tons), consumed 125 kW, and could perform about 1,905 operations per second running on a 2.25 MHz clock. The Central Complex alone (i.e. the processor and memory unit) was 4.3 m by 2.4 m by 2.6 m high. The complete system occupied more than 35.5 m² of floor space.