UNIVAC 418
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The UNIVAC 418 was an 18-bit word core memory machine made by UNIVAC. The name came from its 4 microsecond memory cycle time and 18-bit word. 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.
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[edit] Architecture
The instruction word had three formats:
- Format I
- f - Function code (6 bits)
- u - Operand address (12 bits)
- Format II
- f - Function code (6 bits)
- z - Operand value (12 bits)
- Format III
- f - Function code (6 bits)
- m - Minor function code (6 bits)
- k - Designator (6 bits) used for channel number, shift count, etc.
Numbers were represented in one's complement, single and double precision.
The machine had the following addressable registers:
- A - Register (Double precision Accumulator, 36 bits) composed of:
- AU - Register (Upper Accumulator, 18 bits)
- AL - Register (Lower Accumulator, 18 bits)
- ICR - Register (Index Control Register, 3 bits)
- SR - Register (Special, 4 bits)
- P - Register (Program address, 15 bits)
[edit] UNIVAC 418-I
The first UNIVAC 418-I was delivered in June 1963. It was available with 4,096 to 16,384 words of memory.
[edit] UNIVAC 1218 Military Computer
The 418-I was also available in a militarized version as the UNIVAC 1218. It was almost 6 feet tall and weighted 775 lb. It required both 115VAC, 1-phase, 60 Hz and 115VAC, 3-phase, 400 Hz power.
| Basic System/Component | Purchase Price |
|---|---|
| Minimum 1218 Computer: 4,096 word memory, 4 I/0 | $ 96,000 |
| Most common 1218 Computer: 16,384 word memory, 8 I/0 | $ 127,000 |
| Militarized Mag Tape System (2 handlers) | 80,500 |
| Paper Tape Subsystem including keyboard & printer | 25,000 |
| High speed printer system | 77,500 |
| 80 column card system | 83,250 |
| —————— | |
| Grand Total Minimum 1218 Computer System | $ 362,250 |
| Grand Total Most common 1218 Computer System | $ 393,250 |
[edit] UNIVAC 418-II
The first UNIVAC 418-II was delivered in November 1964. It was available with 4,096 to 65,536 words of memory. Memory cycle time was reduced to 2 microseconds.
[edit] UNIVAC 418-III
The first UNIVAC 418-III was delivered in 1969. It was available with 32,768 to 131,072 words of memory. Memory cycle time was reduced to 750 nanoseconds. New instructions were added for floating-point arithmetic, binary-to-decimal and decimal-to-binary conversions, and block transfers up to 64 words. The SR register was expanded to 6 bits.
By the 1990s, all the 418 hardware was gone, but the California Department of Water Resources was still running 418 emulation on a UNIVAC 1100/60.
[edit] External links
- The UNIVAC 418 Computer Unisys History Newsletter Volume 4, Number 2 August 2000 by George Gray
- UNIVAC 418 documents on bitsavers.org
- UNIVAC 1218 Military Computer 1964 BRL report from Aberdeen Proving Grounds
- The Automated Weather Network The USAF creates a real-time network of UNIVAC 418s
