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UNIVersal Automatic Computer

USA 1951

under construction

eckert and mauchly
Eckert & Mauchly creators of Univac

papers & manuals



The UNIVAC I was the world's first commercially available computer.

picture Smithsonian: the information age


The first UNIVAC I was delivered on June 14, 1951. From 1951 to 1958 a total of 46 UNIVAC I computers were delivered, all of which have since been phased out.

In 1947, John Mauchly chose the name "UNIVAC" (Universal Automatic Computer) for his company's product.

univac 1
Scanned from the Annuals of the History of Computing,  Vol. 3  #4  October  1981

UNIVAC was designed by J. Presper Eckert and John Mauchly (designers of the ENIAC). Their company, the Eckert-Mauchly Computer Company, was purchased by Sperry-Rand.

The UNIVAC handled both numbers and alphabetic characters equally well. The UNIVAC I was unique in that it separated the complex problems of input and output from the actual computation facility. Mercury delay lines were used to store the computer's program. The program circulated within the lines in the form of acoustical pulses that could be read from the line and written into it.

The first UNIVAC came on line for the U.S. Government's Census Bureau. The first commercial customer to purchase a UNIVAC was the Prudential Insurance Company.

In 1952, the UNIVAC I successfully predicted the outcome of the 1952 presidential election, during a televised news broadcast.

General Electric's Appliance Division created the first successful industrial payroll application for the UNIVAC I in 1954.

In 1956, Westinghouse Electric Company installed a UNIVAC computer in its East Pittsburgh plant. The UNIVAC was used to calculate company payrolls, sales records, analysis of sales performance and other company business. The UNIVAC could perform 90,000 transactions per month.

With Walter Cronkite anchoring the CBS 1952 Presidential Election Returns, on nationwide broadcast television, UNIVAC was used to predict who would win the election and become the next President of the United States.

The Computer Debuts on Television

CBS fed the incoming Presidential election results into the UNIVAC which was using one of the first computer databases.  Early in the evening, UNIVAC issused its computational prediction that Eisenhower would win.  Conventional pundits overwhelmingly thought Adlai E. Stevenson would win and that the "computer made an error."  So, CBS withheld its predictions from the air, but as the night went on, Walter Cronkite announced UNIVAC was right and Eisenhower had won. (1)

At the time of General Eisenhower's election in November 1952, the first UNIVAC I was still operating at the Eckert-Mauchly facility in Philadelphia. Shortly thereafter, it was removed to the Census Bureau in Suitland, Maryland USA.(2)


The machine was 25 feet by 50 feet in length, contained 5,600 tubes, 18,000 crystal diodes, and 300 relays. It utilized serial circuitry, 2.25 MHz bit rate, and had an internal storage capacity 1,000 words or 12,000 characters.

univac inside
inside Univac 1

It utilized a Mercury delay line, magnetic tape, and typewriter output.

univac tape
picture courtesy DigiDome: Paul Stuijt

The UNIVAC was used for general purpose computing with large amounts of input and output.

univac mercury delay line
UNIVAC Mercury Delay Line from Univac brochure

Power consumption was about 120 kva. Its reported processing speed was 0.525 milliseconds for arithmetic functions, 2.15 milliseconds for multiplication and 3.9 Milliseconds for division.

The UNIVAC I was also the first computer to come equipped with a magnetic tape unit and was the first computer to use buffer memory.

univac census
univac at the census bureau

Each Univac I was equipped with ten magnetic tape drives each and all were compatible, that is, tapes generated on one drive could be used on any drive. In addition, since input and output operations on magnetic tapes were buffered, they could proceed independent of other central processing tasks which greatly increased throughput. These two characteristics made Univac I uniquely suited for large data-processing tasks. This second computer (installed in 1954) was operated jointly with the Internal Revenue Service, UNIVAC had duplicate arithmetic units, so all errors were immediately detected. Many pioneering software programs for sorting and processing large data files were created on these computers by the Census bureau staff. (2)




The first UNIVAC I was delivered on June 14, 1951 to the census bureau.


It made its star-studded public debut in November 1952 on the CBS television network.

3 UNIVACs were installed and in operation


The first successful industrial payroll application by General Electric.

A second UNIVAC 1, installed literally alongside serial #1, at the Census Bureau. The second computer was identical except that instead of being cooled by recirculating air, it was water-cooled by two 52 ton air-conditioners located in the basement of the building. Since all computer memory was volaitie, programs as well as files were loaded before each run, so the computers were essentially interchangeable. (2)

8 UNIVACs were installed and in operation:

    1. Bureau of the Census, Commerce Dept., Suitland, Maryland
    2. Office of the Air Comptroller, USAF, Washington, D.C.
    3. Army Map Service, U.S. Army, Washington, D.C.
    4. New York University (for Atomic Energy Commission), NY, NY
    5. University of Cal., Radiation Laboratory, Livermore, California
    6. David Taylor Model Basin, U.S.N. Bureau of Ships, Maryland
    7. Prudential Insurance Company
    8. General Electric Company


Westinghouse Electric Company installed a UNIVAC to calculate company payrolls, sales records, analysis of sales performance and other company business.


A total of 46 UNIVAC I computers were delivered



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