UNIVAC was the first commercial computer produced in the United States

Diego García Garijo

UNIVACUniversal Automatic Computer,was designed by the company Remington Rand in the 1950s, it is the very first commercial computer produced in the United States. It was designed principally by John W. Mauchly and John P. Eckert,Eckert for business purpose in public or private companies, the reason was its high cost and installation requirements. This computer was used not only to compile the population census in 1951, but also to predict the result of the 1952 presidential election.UNIVAC I became famous, and it proved to be fast and effective.

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General view of UNIVACs installation

On the left we have Mauchly controlling UNIVAC together with two machine operators.


UNIVAC used 5.000 vacuum tubes, in contrast to ENIAC,which used almost 18.000, this made it possible to reduce the size of its predecessor. It was 3,00 x 4,20 x 2,70 meters, quite smaller than its competitors at this time. John P. Eckert and John W. Mauchlywere the creators of this innovative machine.

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UNIVACs creators studding their new machine

On the left John Presper Eckert and on the right John William Mauchly

This machine was designed using the stored-program principle,this concept came up during ENIACs design development. This device was also designed by Eckert y Mauchly and formalized by the famous physicist and mathematician John von Neumann. The computer architecture consists of a control unit connected to the storage, this storage is also connected with an input device, one output device and with an arithmetic logic unit,The last one execute operations that will be stored in the memory and received by the input device. Both devices, input and output, consisted of magnetic tapes.

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UNIVACs architecture

Punch-card to Tape Converter

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Input and Output Devices

UNIVAC had a delay line memory,which was capable of storing data taking advance of the propagation time of a signal through a physical mean. It was constituted by a tube filled with mercury with a piezoelectric transductor at each end.

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UNIVACs Memory

The image shows the difference in the size of the current memory devices and the complexity of this one.

The magnetic tapedata storage is recorded onto the tape in tracks, over the plastic strip with a magnetized material as iron oxide or chromate.The information stored onto magnetic tapes can be video, audio and data.

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UNIVAC used magnetic tapes.

The storage of all types of data was very new at that time.

Regarding its programming language, UNIVACs memory basic unit is the word. A word always consists of 12 digits or characters. . There are 63 possible characters available, and every 12 digits’ combination is a word. UNIVAC can store 1000 words, displayed into boxes for better comprehension, and each box contains a single word with their respective 12 characters. To refer to each box, a memory addressis used, every location is a box and they are numbered from 000 to 999.

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UNIVACs Memory Boxes

As we can see, both letters and numbers could be stored, up to a total of 1000 words (from 000 to 999).

Using a UNIVAC simulator we have developed a programme which calculates the factorial of a given number. In the lower pics we can see the code of this programme in UNIVAC language (left image). Line [000] contains the command to charge number 1 and starting the multiplication thanks to the command L00 011. The second part of the command from this cell is only a jump. Line [001], contains multiplication command by the stored number in [012] (which will be used as accumulator to multiply it by +1 at a time) and it stores the result of [013], which is the cell where the factorial result will be stored. Then, we charge in rL [012] cell’s content and in rA [010] cell’s content (where the number we are calculating the factorial is located) by means of the commands L m y B m , on the next line, we will compare these registers through the command Q00 009,if both registers are equals, there will be a line break [009] which has to print the result via screen and stop the programme execution. Otherwise, the programme will operate normally on line [005], charge cell [012] one more time and add 1 in order to multiply by the next number once the loop will be complete. In addition, we charge cell [013] to keep the register rL updated. Finally, line [006] has an empty command and an unconditional jump, which redirects the code to line [001], in this way the code is recursively executed until the comparison between [012] and [010] will be complete.You can see all the steps of the execution on the right image, where we can see the simulator debug.

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UNIVACs design and construction had a significant social impact. Of course, how the machine predicted the United States’ presidential election of 1952 played an important role. Policy experts of the time were sure about Democratic candidate‘s success,and during the election an especial programme was performed, Remington Rand‘s new machine would be tested in order to show its full potential to the public. They entered a lot of data from past election to the UNIVAC and only with 7% of the registered voters, a Republican landslide victory was predicted. After the scandal, producers asked Remington Rand to manipulate UNIVACs programmes to change the results in favour of Democratic candidate. At the end, UNIVACs reliability was proved and Republican candidate won the election,The had to apologize to the audience and acknowledge the manipulation of UNIVACs results. It was the start of the fear of computers,because people said that such an accurate prediction with so little data only could be done by beings from other planets.

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Charles Collingwood, Eckert and a UNIVACs I workman the night of the election.

TV presenter of the cannel which the result of United States of America election was announced couldn’t believe UNIVACs prediction.

They were concerned about the way the machine could be commercially viable, it was an important issue into Remington Rand during UNIVACs elaboration Its size and its price were huge, so the chances to make a profit became slight.. This video shows how the machine was advertised and a prove of its potential in New York.

UNIVACs Advertising Video

Thank you very much for your time, we hope you enjoyed UNIVAC.