The IBM 702 was IBM's response to the UNIVAC—the first mainframe computer using magnetic tapes. Because these machines had less computational power than the IBM 701 and ERA 1103, which were favored for scientific computing, the 702 was aimed at business computing.
Fourteen 702s were built. The first one was used at IBM. Due to problems with the Williams tubes, the decision was made to switch to magnetic-core memory instead. The fourteenth 702 was built using magnetic-core memory, and the others were retrofitted with magnetic-core memory.
The 702 was designed for business data processing. Therefore the memory of the computer was oriented toward storing characters. The system used electrostatic storage, consisting of 14, 28, 42, 56, or 70 Williams tubes with a capacity of 1000 bits each for the main memory, giving a memory of 2,000 to 10,000 characters of seven bits each (in increments of 2,000 characters), and 14 Williams tubes with a capacity of 512 bits each for the two 512-character accumulators.
A complete system included the following units:
- IBM 702 Central Processing Unit
- IBM 712 Card Reader
- IBM 756 Card Reader Control Unit
- IBM 717 Printer
- IBM 757 Printer Control Unit
- IBM 722 Card Punch
- IBM 758 Card Punch Control Unit
- IBM 727 Magnetic Tape Unit
- IBM 752 Tape Control Unit
- IBM 732 Magnetic Drum Storage Unit
Total weight (depending on configuration): about 24,645 pounds (12.3 short tons; 11.2 t).
- Pugh, Emerson W.; Johnson, Lyle R.; Palmer, John H. (1991). IBM's 360 and Early 370 Systems. MIT Press. pp. 26–27. ISBN 0-262-16123-0.
- Yates, JoAnne (May 17, 2005). Structuring the Information Age: Life Insurance and Technology in the Twentieth Century. JHU Press. p. 161. ISBN 9780801880865.
- Bashe, Charles J.; Johnson, Lyle R.; Palmer, John H.; Pugh, Emerson W. (1985). IBM's Early Computers. MIT Press. pp. 176–178. ISBN 0-262-02225-7.
- Pugh, Emerson W.; Johnson, Lyle R.; Palmer, John H. (1991). IBM's 360 and Early 370 Systems. MIT Press. pp. 25–26. ISBN 0-262-16123-0.
- Weight with only one tape unit:
32,844 lbs - 9,110 lbs + (9,110 lbs / 10) = 23734 + 911 = 24645 lbs
32,844 pounds (16.4 short tons; 14.9 t)
- Weik, Martin H. (March 1961). "IBM 702". ed-thelen.org. A Third Survey of Domestic Electronic Digital Computing Systems.