UNIVAC 418
| Industry | Computer hardware |
|---|---|
| Products | UNIVAC 418 computer system |
The UNIVAC 418 was a transistor-based computer system created by Sperry Univac, utilizing 18-bit word lengths and magnetic-core memory. Its designation originated from the combination of an 18-bit word size and a 4-microsecond memory cycle time. The assembly languages designed for this family were known as TRIM III and ART418.
Across three different versions, the production exceeded 392 units. The system’s architecture was derived from the Control Unit Tester (CUT), a device initially developed for testing peripherals in more extensive computer systems.
Architecture
The instruction word was structured into three distinct formats:
- Format I - utilized for standard operations such as Load, Store, and Arithmetic
- f - Function field (6 bits)
- u - Operand address field (12 bits)
- Format II - used for constant arithmetic and Boolean operations
- f - Function field (6 bits)
- z - Operand address or immediate value (12 bits)
- Format III - dedicated to Input/Output instructions
- f - Function field (6 bits)
- m - Minor function field (6 bits)
- k - Designator field (6 bits), applied for channel numbers, shift counts, and similar purposes
The numeric representation employed ones' complement, supporting both single and double precision floating-point formats. Due to the 18-bit word length being divisible by three rather than four, TRIM assembly language source code utilized octal notation.
Registers accessible by the system included:
- A - Double precision Accumulator consisting of 36 bits, subdivided into:
- AU - Upper Accumulator segment (18 bits)
- AL - Lower Accumulator segment (18 bits)
- ICR - Index Control Register, also called the "B-register" (3 bits)
- SR - Special Register (4 bits), functioning as a paging register to access memory banks beyond the current one
- P - Program address register holding 15 bits
Register contents were displayed live on the system’s front panel in binary form. User interaction with registers was possible through push buttons, but only while the machine was stopped.
UNIVAC 418-I
The initial model, UNIVAC 418-I, was delivered starting June 1963, offering memory sizes ranging between 4,096 and 16,384 words.
UNIVAC 1218 Military Computer
A military adaptation of the 418-I was known as the UNIVAC 1218. This version stood nearly six feet tall and weighed . It required dual power inputs: 115VAC single-phase at 60 Hz and 115VAC three-phase at 400 Hz.
| System/component | Price |
|---|---|
| Minimum configuration: 1218 computer with 4,096-word memory and 4 I/O channels | $96,000 |
| Most typical configuration: 1218 computer with 16,384-word memory and 8 I/O channels | $127,000 |
| Militarized magnetic tape system including two handlers | $80,500 |
| Paper tape subsystem equipped with keyboard and printer | $25,000 |
| High-speed printer system | $77,500 |
| 80-column card system | $83,250 |
| ———— | |
| Total cost for minimum configuration of the 1218 system | $362,250 |
| Total cost for most common configuration of the 1218 system | $393,250 |
UNIVAC 418-II
Introduced in November 1964, the UNIVAC 418-II provided memory options from 4,096 up to 65,536 words of 18 bits each and improved performance with a shortened memory cycle time of 2 microseconds. Its military counterpart was designated as the UNIVAC 1219 ("Mk 152 Fire Control Computer") and was incorporated into the Navy’s Mk 76 missile fire control apparatus to manage the AN/SPG-55 radar system.
UNIVAC 418-III
Introduced in 1969, the UNIVAC 418-III featured memory sizes ranging from 32,768 to 131,072 words and operated with an improved cycle time of 750 nanoseconds. This model incorporated new instruction sets for floating-point calculations, binary-decimal conversions, and supported block transfers of up to 64 words. The SR register was enhanced to six bits in length. Distinctive hardware capabilities, such as buffer overflow interrupts and hardware-enabled buffer chaining, facilitated efficient processing of high-speed serial character streams.
Although the original 418 hardware was phased out by the 1990s, the California Department of Water Resources maintained UNIVAC 418 emulation running on a UNIVAC 1100/60 system. Among its prominent users was London's Royal London Hospital, which deployed a UNIVAC 418-III in 1973.