UNIVAC 1105

UNIVAC 1105 operator console, in front of the cabinets containing the CPU and memory.
The U.S. Census Bureau used 1105s to process the 1960 census.

The UNIVAC 1105 was a follow-on computer to the UNIVAC 1103A introduced by Sperry Rand in September 1958. [1] The UNIVAC 1105 used 21 types of vacuum tubes, 11 types of diodes, 10 types of transistors, and three core types.

The UNIVAC 1105 had either 8,192 or 12,288 words of 36-bit magnetic core memory, in two or three banks of 4,096 words each.[2] Magnetic drum memory provided either 16,384 or 32,768 words, in one or two drums with 16,384 words each. Sixteen to twenty-four UNISERVO II tape drives were connected, with a maximum capacity (not counting block overhead) of 1,200,000 words per tape. Major differences from the 1103A were in the addition of a buffered Input/Output system consisting of two 120-word buffers which allowed for overlapping of magnetic tape reading with writing at the same time.[1][2][3]

Fixed-point numbers had a one-bit sign and a 35-bit value, with negative values represented in ones' complement format. Floating-point numbers had a one-bit sign, an eight-bit characteristic, and a 27-bit mantissa. Instructions had a six-bit operation code and two 15-bit operand addresses.[4]

A complete UNIVAC 1105 computer system required 160 kW of power (175 KVA, 0.9 power factor) and an air conditioning unit with a power of at least 35 tons (123 kW) for cooling input water. The computer system weighed about 57,089 pounds (28.5 short tons; 25.9 t) with a floor loading of 47 lb/ft2 (230 kg/m2) and required a room 49 x 64 x 10 ft (15 x 20 x 3 m). The floor space for the computer was approximately 3,752 ft2 (350 m2). The power, refrigeration and equipment room was approximately 2,450 ft2 (230 m2).[4]

  1. ^ a b Gray, G.; Smith, R. (July 1998). "Sperry Rand's transistor computers". IEEE Annals of the History of Computing. 20 (3): 16–26. doi:10.1109/85.707571. Retrieved 17 June 2024.
  2. ^ a b Petschauer, Richard J (1990). History and Evolution of 1100/2200 Mainframe Technology (PDF). USE Conference. Bladensburg, MD: USE User Group.
  3. ^ "Report "S"" (PDF). BitSavers.org. RCA Product Planning. Retrieved 17 June 2024.
  4. ^ a b Weik, Martin (1961). "A THIRD SURVEY OF DOMESTIC ELECTRONIC DIGITAL COMPUTING SYSTEMS". www.ed-thelen.org. Retrieved 2020-03-20.