UNIVAC III
| Company type | Computer system |
|---|---|
| Industry | Computing |
| Founded | 1958 |
| Headquarters | Philadelphia , United States |
| Products | Mainframe computer |
| Parent | Remington Rand UNIVAC |
The UNIVAC III was created by the Philadelphia branch of Remington Rand UNIVAC beginning in 1958 as a transistor-based follow-up to the earlier vacuum tube models UNIVAC I and II. Although it was announced in 1960, deliveries did not commence until June 1962, primarily because the division concentrated on the UNIVAC LARC initiative. From June 1962 onward, Westinghouse collaborated on programming and marketing efforts for the system. Its architecture was designed to accommodate all data formats; however, the unique word length and instruction set necessitated complete rewriting of existing software, which led many clients to opt for alternative suppliers instead of upgrading.
The machine weighed approximately , and its design aimed to reduce reliance on expensive core memory. The memory was organized with a width of 25 bits and could be configured between 8,192 and 32,768 words. This memory was constructed in stacks comprising 29 planes, which included planes dedicated to data storage, error detection, and spare capacity. Each cabinet could contain up to four such stacks, totaling 16,384 words.
Supported data types included:
- Signed binary numbers represented in 25 bits
- Six-digit signed decimal numbers encoded using excess-3 binary-coded decimal
- Six-bit alphanumeric characters enabling four-character signed values
Instructions were encoded in 25-bit words. The central processing unit incorporated four accumulators selected via a four-bit field (ar), allowing operations on data ranging from one to four words. Two accumulators could hold a 12-digit decimal number, while three accumulators could represent a 12-character alphanumeric string. In combined operations, the sign bit of the highest-order accumulator was utilized.
Fifteen index registers were available, with selection controlled by a four-bit field (x) acting as the base register for addressing. Operand addresses were computed by adding the base register's contents to a 10-bit displacement value. Another four-bit field (xo) was used to choose index registers for modification or storage purposes.
Addressing modes featured indirect addressing and field selection governed by a single-bit field (i/a), which allowed flexible combinations of indirect addressing and base register usage depending on the instruction context.
Sperry Rand delivered a total of 96 UNIVAC III units. The operating systems provided included CHIEF and BOSS, while assembly programming was performed using SALT. Most installations were equipped with magnetic tape drives that stored system images followed by user data and job control records. The systems supported up to 32 tape drives; some later models incorporated random-access FASTRAND drum storage devices.
See also
External links
- UNIVAC III Data Processing System "A Third Survey of Domestic Electronic Digital Computing Systems" Report No. 1115, March 1961 by Martin H. Weik, Ballistic Research Laboratories (system not yet available; 25 units ordered with 18-month delivery)
- The UNIVAC III Computer (archived)
- UNIVAC III Photos
- UNIVAC III Installations (serial numbers)
- UNIVAC III Documentation (PDF) on bitsavers.org
- YouTube Video: "UNIVAC III Origin and History"