UNIVAC III
The UNIVAC III, designed as an improved transistorized replacement for the vacuum tube UNIVAC I and UNIVAC II computers, was introduced in June 1962, with Westinghouse agreeing to furnish system programing & marketing on June 1, 1962. It was designed to be compatible for all data formats. However the word size and instruction set were completely different; this presented significant difficulty as all programs had to be rewritten, so many customers switched to different vendors instead of upgrading existing UNIVACs.
The system was engineered to use as little core memory as possible, as it was a very expensive item. They used a memory system which had 25 bits width, and could be configured with from 8,192 words to 32,768 words of memory. Memory was built in stacks of 29 planes of 4,096 cores: 25 for the data word, 2 for "modulo-3 check" bits, and 2 for spares. Each memory cabinet held up to four stacks (16,384 words).
It supported the following data formats:
UNIVAC 418
The UNIVAC 418 was a transistorized, 18-bit word core memory machine made by Sperry Univac. The name came from its 4-microsecond memory cycle time and 18-bit word. The assembly language for this class of computers was TRIM III and ART418.
Over the three different models, more than 392 systems were manufactured. It evolved from the Control Unit Tester (CUT), a device used in the factory to test peripherals for larger systems.
Architecture
The instruction word had three formats:
Numbers were represented in ones' complement, single and double precision. The TRIM assembly source code used octal numbers as opposed to more common hexadecimal because the 18-bit words are evenly divisible by 3, but not by 4.
The machine had the following addressable registers:
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