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UNIVAC 1103 & 1103A

The UNIVAC 1103 or ERA 1103, a successor to the UNIVAC 1101, was a computer system designed by Engineering Research Associates and built by the Remington Rand corporation in October, 1953.

The system used electrostatic storage, consisting of 36 Williams tubes with a capacity of 1024 bits each, giving a total random access memory of 1024 words of 36 bits each. Each of the 36 Williams tubes was five inches in diameter. A magnetic drum memory provided 16,384 words. Both the electrostatic and drum memories were directly addressable: addresses 0 through 01777 (Octal) were in electrostatic memory and 040000 through 077777 (Octal) were on the drum.

Fixed-point numbers had a 1-bit sign and a 35-bit value, with negative values represented in one's complement format.

Instructions had a 6-bit operation code and two 15-bit operand addresses.

Programming systems for the machine included the RECO regional coding assembler by Remington-Rand, the RAWOOP one-pass assembler and SNAP floating point interpretive system authored by the Ramo-Wooldridge Corporation of Los Angeles, the FLIP floating point interpretive system by Consolidated Vultee Aircraft of San Diego, and the CHIP floating point interpretive system by Wright Field in Ohio

The UNIVAC 1103A or Univac Scientific was an upgraded version of the UNIVAC 1103 introduced by Sperry Rand in March, 1956.

The UNIVAC 1103A had up to 12,288 words of 36 bit magnetic core memory, in one to three banks of 4,096 words each.

Fixed-point numbers had a 1 bit sign and a 35 bit value, with negative values represented in one's complement format.

Floating-point numbers had a 1 bit sign, an 8 bit characteristic, and a 27 bit mantissa.

Instructions had a 6 bit operation code and two 15-bit operand addresses.

The 1103A was contemporary to the IBM 704, which also employed vacuum tube logic, magnetic core memory, and hardware floating point.