UNIVAC I


The UNIVAC I was the first general-purpose electronic digital computer for business applications produced in the United States. It was designed principally by J. Presper Eckert and John Mauchly, the inventors of the ENIAC. Design work was started 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 accepted by the United States Census Bureau on March 31, 1951, and was dedicated on June 14 that year. The fifth machine was used by CBS to predict the result of the 1952 presidential election. With a sample of a mere 5.5% of the voter turnout, it famously predicted an Eisenhower landslide.

History

Development and design

In early 1946, months after the completion of ENIAC, the University of Pennsylvania adopted a new patent policy, which would've required Eckert and Mauchly to assign all their patents to the university if they stayed beyond spring of that year. Unable to reach an agreement with the university, the duo left the Moore School of Electrical Engineering in March 1946, along with much of the senior engineering staff. Simultaneously, the duo founded the Electronic Control Company in Philadelphia. When the duo was given a $300,000 deposit for research by the United States Census Bureau, the conception of the UNIVAC I began in April 1946, a month after they founded their company. Later in August of that year, during the last of the Moore School Lectures, the Moore School team members were proposing new technological designs for the EDVAC computer and its stored program concept. They were also simultaneously conceiving ideas for a potential successor model to the EDVAC, which were under the working titles of "Parallel-Type EDVAC," "Statistical EDVAC," and simply, "EDVAC II."
In April 1947, Eckert and Mauchly created the tentative instruction code, C-1, for their potential successor model to the EDVAC, which was the earliest document on the programming of an electronic digital computer intended for commercial use. A month later, they renamed their next project to "the UNIVAC." Later in October of that year, the duo drafted, which was a mercury acoustic delay-line electronic memory system. The patent was eventually accepted in February 1953 as the "first device to gain widespread acceptance as a reliable computer memory system." Meanwhile, in November 1947, the Electronic Control Company began advertising the UNIVAC I. In 1948, the company, renamed the Eckert-Mauchly Computer Corporation, secured a contract with the United States Census Bureau to begin construction on the UNIVAC I. At the same time, Harry Straus, impressed with the development of the duo's next invention, convinced the directors of American Totalisator to invest $500,000 to shore up the financially troubled Eckert-Mauchly Computer Corporation.
In early 1949, Betty Holberton, one of the developers of the project, made the UNIVAC Instructions Code C-10, the first software to allow a computer to be operated by keyboarded commands rather than dials and switches. At the same time, Grace Hopper left the Harvard Computation Laboratory to join the EMCC as a senior mathematician and programmer to help develop the UNIVAC I. Later in June of that year, Mauchly conceived Short Code—the first high-level programming language for an electronic computer—to be used with the BINAC. The Short Code was later tested on the UNIVAC I in early 1950. Meanwhile, in September 1949, by the time the BINAC was delivered to Northrop Aircraft, Eckert and Mauchly received six new orders for the UNIVAC I, so they decided to focus on finishing the UNIVAC I. Unfortunately for them, a month later, Harry Straus was killed when his twin-engine airplane crashed, causing American Totalisator to withdraw their promise of financial support. This was quickly undone when Remington Rand bought the duo's company in February 1950 to help finish construction on the UNIVAC I. The company then became Remington Rand's "Eckert-Mauchly Division." Construction of the UNIVAC I was completed by December 1950, and it was later delivered to the United States Census Bureau in March 1951 so data could be processed more quickly and accurately.

Market positioning

The UNIVAC I was the first American computer designed at the outset for business and administrative use with fast execution of relatively simple arithmetic and data transport operations, as opposed to the complex numerical calculations required of scientific computers. As such, the UNIVAC competed directly against punch-card machines, though the UNIVAC originally could neither read nor punch cards. That shortcoming hindered sales to companies concerned about the high cost of manually converting large quantities of existing data stored on cards. This was corrected by adding offline card processing equipment, the UNIVAC Tape to Card converter, to transfer data between cards and UNIVAC magnetic tapes. However, the early market share of the UNIVAC I was lower than the Remington Rand Company wished.
To promote sales, the company partnered with CBS to have UNIVAC I predict the result of the 1952 United States presidential election live on television. The machine predicted that Dwight D. Eisenhower would win in a landslide over Adlai Stevenson at a chance of 100 to 1, receive 32,915,949 votes and win the Electoral College 438–93. It was opposed to the final Gallup Poll, which had predicted that Eisenhower would win in a close contest. The CBS crew was so certain that UNIVAC was wrong that they believed it was not working, so they changed a certain "national trend factor" from 40% to 4% to obtain what appeared more correct 268–263, and released that for the television. It was soon noticed that the prediction assuming 40% was closer to truth, so they changed it back.
On election night, Eisenhower received 34,075,029 votes in a 442–89 Electoral College victory. UNIVAC had a margin of error of 3.5% of Eisenhower's popular vote tally and was within four votes of his electoral vote total. The prediction and its use in CBS's election coverage gave rise to a greater public awareness of computing technology, while computerized predictions became a widely used part of election night broadcasts.

Installations

The first contracts were with government agencies such as the Census Bureau, the U.S. Air Force, and the U.S. Army Map Service. Contracts were also signed by the ACNielsen Company, and the Prudential Insurance Company. Following the sale of Eckert–Mauchly Computer Corporation to Remington Rand in 1950, due to the cost overruns on the project, Remington Rand convinced Nielsen and Prudential to cancel their contracts.
The first sale, to the Census Bureau, was marked with a formal ceremony on March 31, 1951, at the Eckert–Mauchly Division's factory at 3747 Ridge Avenue, Philadelphia. The machine was not actually shipped until the following December, because, as the sole fully set-up model, it was needed for demonstration purposes, and the company was apprehensive about the difficulties of dismantling, transporting, and reassembling the delicate machine. As a result, the first installation was with the second computer, delivered to the Pentagon in June 1952.

UNIVAC installations, 1951–1954

Originally priced at US$159,000, the UNIVAC I rose in price until they were between $1,250,000 and $1,500,000. A total of 46 systems were eventually built and delivered.
The UNIVAC I was too expensive for most universities, and Sperry Rand, unlike companies such as IBM, was not strong enough financially to afford to give many away. However, Sperry Rand donated UNIVAC I systems to Harvard University, the University of Pennsylvania, and Case Institute of Technology in Cleveland, Ohio. The UNIVAC I at Case was still operable in 1965 but had been supplanted by a UNIVAC 1107.
A few UNIVAC I systems stayed in service long after they were made obsolete by advancing technology. The Census Bureau used its two systems until 1963, amounting to 12 and 9 years of service, respectively. Sperry Rand itself used two systems in Buffalo, New York until 1968. The insurance company Life and Casualty of Tennessee used its system until 1970, totalling over 13 years of service.

Technical description

Major physical features

UNIVAC I used 6,103 vacuum tubes, weighed, consumed 125 kW, and could perform about 1,905 operations per second running on a 2.25 MHz clock. The Central Complex alone 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.

Main memory details

The main memory consisted of 1000 words of 12 characters each. When representing numbers, they were written as 11 decimal digits plus sign. The 1000 words of memory consisted of 100 channels of 10-word mercury delay-line registers. The input/output buffers were 60 words each, consisting of 12 channels of 10-word mercury delay-line registers. There are six channels of 10-word mercury delay-line registers as spares. With modified circuitry, seven more channels control the temperature of the seven mercury tanks, and one more channel is used for the 10-word "Y" register. The total of 126 mercury channels is contained in the seven mercury tanks mounted on the backs of sections MT, MV, MX, NT, NV, NX, and GV. Each mercury tank is divided into 18 mercury channels.
Each 10-word mercury delay-line channel is made up of three sections:
  1. A channel in a column of mercury, with receiving and transmitting quartz piezo-electric crystals mounted at opposite ends.
  2. An intermediate frequency chassis, connected to the receiving crystal, containing amplifiers, detector, and compensating delay, mounted on the shell of the mercury tank.
  3. A recirculation chassis, containing cathode follower, pulse former and retimer, modulator, which drives the transmitting crystal, and input, clear, and memory-switch gates, mounted in the sections adjacent to the mercury tanks.