The Atanasoff-Berry Computer

It was generally believed that the first electronic digital computers were the Colossus, built in England in 1943, and the ENIAC, built in the United States in 1945. However, the first special-purpose electronic computer may actually have been invented by John Vincent Atanasoff, a physicist and mathematician at Iowa State College (now Iowa State University), during 1937–42. Together with his graduate assistant Clifford E. Berry, Atanasoff built a successful small prototype in 1939 for the purpose of testing two ideas central to his design: capacitors to store data in binary form and electronic logic circuits to perform addition and subtraction. They then began the design and construction of a larger, more general-purpose computer, known as the Atanasoff-Berry Computer, or ABC.

Various components of the ABC were designed and built from 1939 to 1942, but development was discontinued with the onset of World War II. The ABC featured about 300 vacuum tubes for control and arithmetic calculations, use of binary numbers, logic operations (instead of direct counting), memory capacitors, and punched cards as input/output units. At Atanasoff's invitation, another early computer pioneer, John Mauchly, stayed at his home and was freely shown his work for several days in June 1941.

Howard Aiken's digital calculators

While Bush was working on analog computing at MIT, across town Harvard professor Howard Aiken was working with digital devices for calculation. He had begun to realize in hardware something like Babbage's Analytical Engine, which he had read about. Starting in 1937, he laid out detailed plans for a series of four calculating machines of increasing sophistication, based on different technologies, from the largely mechanical Mark I to the electronic Mark IV.

Aiken was methodically exploring the technological advances made since the mechanical assembly and steam power available to Babbage. Electromagnetic relay circuits were already being used in business machines, and the vacuum tube—a switch with no moving parts, very high speed action, and greater reliability than electromechanical relays—was quickly put to use in the early experimental machines.

The business machines of the time used plugboards (something like telephone switchboards) to route data manually, and Aiken chose not to use them for the specification of instructions. This turned out to make his machine much easier to program than the more famous ENIAC, designed somewhat later, which had to be manually rewired for each program.

From 1939 to 1944 Aiken, in collaboration with IBM, developed his first fully functional computer, known as the Harvard Mark I. The machine, like Babbage's, was huge: more than 50 feet (15 metres) long, weighing five tons, and consisting of about 750,000 separate parts, it was mostly mechanical. For input and output it used three paper tape readers, two card readers, a card punch, and two typewriters. It took between three and six seconds to add two numbers. Aiken developed three more such machines (Mark II–IV) over the next few years and is credited with developing the first fully automatic large-scale calculator.

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№ 4. ENIAC

ENIAC (Electronic Numerical Integrator And Computer), the first large-scale, general purpose, digital computer. ENIAC was initially built for the United States military to calculate the paths of artillery shells. It was later used to make calculations for nuclear weapons research, weather prediction, and wind tunnel design. ENIAC was introduced to the public in February 1946 and was used until October 1955.

ENIAC was built by American physicist John W. Mauchly and American electrical engineer John Presper Eckert, Jr., at the Moore School of Electrical Engineering, University of Pennsylvania. Eckert and Mauchly successfully demonstrated ENIAC less than three years after the Army commissioned its construction. In 1947 ENIAC was moved from the University of Pennsylvania to its permanent home at the Aberdeen Proving Ground in Maryland. Only one system of its type was ever built, but it operated continuously until October 1955.

Unlike modern computers, which use microprocessors composed of thousands or millions of transistors, ENIAC used vacuum tubes to process data. It had about 18,000 tubes, each the size of a small light bulb. The computer was composed of 30 separate units with additional power supplies and cooling units. It weighed more than 30 tons, occupied 1800 sq ft and consumed 175 kw of power.

ENIAC contained 20 special storage registers called accumulators that stored intermediate and final calculations. Each accumulator held a ten-digit number. ENIAC used decimal arithmetic in its operations rather than the binary arithmetic common in today’s computers (see Number Systems). ENIAC could perform about 5000 calculations per second—more than 10,000 times slower than modern personal computers. It took ENIAC about 20 seconds to solve problems that had taken one or two days to complete manually. Initially, scientists programmed and entered data into ENIAC by manually setting switches and rewiring the machine. Later, a more efficient IBM punch-card reading machine was used to input data, while another IBM punch-card machine was used to store data. When ENIAC completed a calculation, it would notify operators by turning on a sequence of lights or punching certain sequences of cards.

ENIAC was designed to calculate continuously, day and night. However, because its circuitry was composed of a vast number of vacuum tubes that tended to burn out, ENIAC had to be constantly serviced. This continual servicing considerably reduced ENIAC’s net operating time. During a typical week, ENIAC was down for maintenance about one-third of the time. As soon as they completed the ENIAC design, Eckert and Mauchly signed a contract to build a successor, which they called EDVAC for Electronic Discrete Variable Automatic Computer. This more efficient design reduced the number of vacuum tubes in the EDVAC to about 4000.

Although it was the first large-scale machine to do routine calculations in a production environment, the ENIAC was not the first electronic computer. Between 1939 and 1942, John Atanasoff, a physics and mathematics professor at Iowa State University, and his graduate student Clifford Berry, assembled the Atanasoff-Berry Computer, which incorporated many digital circuit design innovations. Their system used the binary arithmetic system of 1s and 0s commonly used in today’s computers as well as a memory drum that stored data in a method similar to the storage technique used in modern memory chips.

After Eckert and Mauchly were granted a patent for the ENIAC, a long court battle began over who actually created the first modern electronic computer. Finally, in 1973, a federal judge invalidated the ENIAC patent and awarded recognition to Atanasoff and Berry, more than 30 years after their pioneering accomplishments.

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№ 5. UNIVAC

UNIVAC, (UNIVersal Automatic Computer), the first electronic computer designed and sold to solve commercial problems. The UNIVAC contained about 5000 vacuum tubes, occupied 943 cubic feet, and weighed 8 tons. From 1951 to 1957 a variety of governmental and commercial customers bought a total of 48 UNIVAC computers.

The UNIVAC was a successor to the first general-purpose electronic computer, the ENIAC (Electronic Numerical Integrator And Calculator). The ENIAC was built for the United States armed services by American physicist John Presper Eckert, Jr., and American electrical engineer John Mauchly between 1943 and 1946. It was the first large-scale, general-purpose electronic computer. In 1947 and 1948 Eckert and Mauchly built an improved machine called the EDVAC (Electronic Discrete Variable Automatic Computer), which incorporated some important design innovations by Hungarian American mathematician John von Neumann. In December 1948 Eckert and Mauchly left the University of Pennsylvania, where they had worked, and formally organized the Eckert-Mauchly Computer Corporation. In August 1949 they delivered a computer for (onboard) missile control to the Northrup Corporation, which they called BINAC (BINary Automatic Computer). BINAC was to be the prototype for the commercial UNIVAC system.

In March 1951 Eckert and Mauchly delivered the first UNIVAC to the U.S. Census Bureau. The UNIVAC gained national attention in 1952 when General Dwight D. Eisenhower was running against Adlai E. Stevenson for the presidency of the United States. A UNIVAC was used to predict the results of the election on national television. Using an early ballot count of only a few percent of the votes, UNIVAC predicted a landslide win for Eisenhower. The television networks delayed announcement of the predicted margin until a greater percentage of election returns could be counted. When a large enough percentage of the votes was finally counted, it was found that UNIVAC had been correct in its predictions. This successful demonstration contributed greatly to the popularity of the UNIVAC as well as to the public’s opinion of computers.

The UNIVAC contained many improvements over the earlier ENIAC. The number of vacuum tubes in the UNIVAC was reduced to about 5000 from ENIAC’s 19,000. UNIVAC’s 943 cubic feet of cabinets took up less floor space than ENIAC, but it still would have filled a single-car garage. The UNIVAC weighed 8 tons instead of the ENIAC’s 30 tons, and it consumed about 100 kilowatts of power instead of the 175 kilowatts of power that the ENIAC used. Despite the major improvements of the UNIVAC over the ENIAC, it was still extremely inefficient by today’s standards.

UNIVAC, like its predecessor ENIAC, used decimal arithmetic with vacuum tube logic, counting serially up and down to ten with each string of vacuum tubes in the arithmetic storage registers. UNIVAC’s memory, holding both the data and program, was built from mercury delay-line tubes. These large horizontal cylinders contained liquid mercury that circulated acoustic vibrations representing stored data and instruction values. Each memory line could accommodate 1024 words, with each word holding one 12-digit data value or two 6-digit instruction values. External data could be read from and written to magnetic tape, as well as from punch cards and to printers. The UNIVAC could perform up to 1905 operations per second. Primarily designed for business applications, the UNIVAC worked well with both fixed-precision decimal digits and text character data. Early UNIVAC customers included government agencies, the A. C. Nielsen Company, the Prudential Insurance Company, and the General Electric Appliance Division. UNIVAC computers were used for many different purposes, including accounting, data processing, and record keeping.

Before Eckert and Mauchly began production of the UNIVAC system, they realized that they would need significant financial support to start the production of multiple systems and to support these systems. This was particularly true since most customers wanted to lease the computers rather than buy them outright, due to their high cost—about $1 million. Because of financial difficulties, Remington Rand bought the Eckert-Mauchly Computer Corporation in 1950 and changed its name to the Univac Division of Remington Rand. In the early 1950s another company, Electronic Research Associates (ERA) of St. Paul, Minnesota, was building computers for scientific applications requiring higher precision arithmetic than the UNIVAC performed. In 1952 Remington Rand bought ERA and the two groups worked together to produce later models of the UNIVAC computer series.

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№ 6. Early Electronic Calculators

Herman Hollerith, an American inventor, used an idea similar to Jacquard’s loom when he combined the use of punched cards with devices that created and electronically read the cards. Hollerith’s tabulator was used for the 1890 U.S. census, and it made the computational time three to four times shorter than the time previously needed for hand counts. Hollerith’s Tabulating Machine Company eventually merged with two companies to form the Computing-Tabulating-Recording Company. In 1924 the company changed its name to International Business Machines (IBM).

In 1936 British mathematician Alan Turing proposed the idea of a machine that could process equations without human direction. The machine (now known as a Turing machine) resembled an automatic typewriter that used symbols for math and logic instead of letters. Turing intended the device to be a “universal machine” that could be used to duplicate or represent the function of any other existing machine. Turing’s machine was the theoretical precursor to the modern digital computer. The Turing machine model is still used by modern computational theorists.

In the 1930s American mathematician Howard Aiken developed the Mark I calculating machine, which was built by IBM. This electronic calculating machine used relays and electromagnetic components to replace mechanical components. In later machines, Aiken used vacuum tubes and solid state transistors (tiny electrical switches) to manipulate the binary numbers. Aiken also introduced computers to universities by establishing the first computer science program at Harvard University in Cambridge, Massachusetts. Aiken obsessively mistrusted the concept of storing a program within the computer, insisting that the integrity of the machine could be maintained only through a strict separation of program instructions from data. His computer had to read instructions from punched cards, which could be stored away from the computer. He also urged the National Bureau of Standards not to support the development of computers, insisting that there would never be a need for more than five or six of them nationwide.

		ENIAC

At the Institute for Advanced Study in Princeton, New Jersey, Hungarian-American mathematician John von Neumann developed one of the first computers used to solve problems in mathematics, meteorology, economics, and hydrodynamics. Von Neumann's 1945 design for the Electronic Discrete Variable Automatic Computer (EDVAC)—in stark contrast to the designs of Aiken, his contemporary—was the first electronic computer design to incorporate a program stored entirely within its memory. This machine led to several others, some with clever names like ILLIAC, JOHNNIAC, and MANIAC.

American physicist John Mauchly proposed the electronic digital computer called ENIAC, the Electronic Numerical Integrator And Computer. He helped build it along with American engineer John Presper Eckert, Jr., at the Moore School of Engineering at the University of Pennsylvania in Philadelphia. ENIAC was operational in 1945 and introduced to the public in 1946. It is regarded as the first successful, general digital computer. It occupied 167 sq m (1,800 sq ft), weighed more than 27,000 kg (60,000 lb), and contained more than 18,000 vacuum tubes. Roughly 2,000 of the computer’s vacuum tubes were replaced each month by a team of six technicians. Many of ENIAC’s first tasks were for military purposes, such as calculating ballistic firing tables and designing atomic weapons. Since ENIAC was initially not a stored program machine, it had to be reprogrammed for each task.

	UNIVAC Computer System
	The first commercially available electronic computer, UNIVAC I, was also the first computer to handle both numeric and textual information. Designed by John Presper Eckert, Jr., and John Mauchly, whose corporation subsequently passed to Remington Rand, the implementation of the machine marked the beginning of the computer era. Here, a UNIVAC computer is shown in action. The central computer is in the background, and in the foreground is the supervisory control panel. Remington Rand delivered the first UNIVAC machine to the U.S. Bureau of Census in 1951.

Eckert and Mauchly eventually formed their own company, which was then bought by the Rand Corporation. They produced the Universal Automatic Computer (UNIVAC), which was used for a broader variety of commercial applications. The first UNIVAC was delivered to the United States Census Bureau in 1951. By 1957, there were 46 UNIVACs in use.

Between 1937 and 1939, while teaching at Iowa State College, American physicist John Vincent Atanasoff built a prototype computing device called the Atanasoff-Berry Computer, or ABC, with the help of his assistant, Clifford Berry. Atanasoff developed the concepts that were later used in the design of the ENIAC. Atanasoff’s device was the first computer to separate data processing from memory, but it is not clear whether a functional version was ever built. Atanasoff did not receive credit for his contributions until 1973, when a lawsuit regarding the patent on ENIAC was settled.

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