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 IIIcite book
title = UNIVAC 1219 Macro Assembler - Operating Instructions
edition =
last = Neissen
first = C.W.
coauthors =
year = 1966
publisher =
id = M.I.T. Lincoln Laboratory report MIT-LIN-62L-0097
pages = ] 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::"Format I" - common Load, Store, and Arithmetic operations
*f - Function code (6 bits)
*u - Operand address (12 bits):"Format II" - Constant arithmetic and Boolean functions
*f - Function code (6 bits)
*z - Operand address or value (12 bits):"Format III" - Input/Output
*f - Function code (6 bits)
*m - Minor function code (6 bits)
*k - Designator (6 bits) used for channel number, shift count, etc. [ [http://www.cc.gatech.edu/~randy/folklore/v4n2.html The UNIVAC 418 Computer, Unisys History Newsletter Volume 4, Number 2 August 2000, by George Gray] ]

Numbers were represented in one's complement, single and double precision. The TRIM assembly source code used octal numbers as opposed to more common hexadecimalFact|date=January 2008 because the 18-bit words are evenly divisible by 3, but not by 4.

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), also designated the "B-register"
*SR - Register ("Special Register", 4 bits), a paging register allowing direct access to memory banks other than the executing ("P" register) bank
*P - Register (Program address, 15 bits)

All register values were displayed in real time on the front panel of the computer in binary, with the ability of the user to enter new values via push button (a function that was safe to perform only when the computer was not in "run" mode).

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.

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.

UNIVAC 418-II

The first UNIVAC 418-II was delivered in November 1964. It was available with 4,096 to 65,536 (18-bit) words of memory. Memory cycle time was reduced to 2 microseconds. The militarized version was called the UNIVAC 1219 (known as the "Mk 152 Fire Control Computer.") [http://www.usfamily.net/web/labenson/SystemsInternational.htm "Japanese Navy Projects"] cite book
title = Liberty Call
edition =
last = Haynes
first = Mark S.
coauthors =
year = 1991
publisher =
id =
pages = ] It was part of the Navy's Mk 76 missile fire control system, used to control the AN/SPG-55 radar system.

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.

References

External links

* [http://www.cc.gatech.edu/~randy/folklore/v4n2.html The UNIVAC 418 Computer] Unisys History Newsletter Volume 4, Number 2 August 2000 by George Gray
* [http://www.bitsavers.org/pdf/univac/418/ UNIVAC 418 documents on bitsavers.org]
* [http://ed-thelen.org/comp-hist/BRL64-u.html#UNIVAC-1218 UNIVAC 1218 Military Computer] 1964 BRL report from Aberdeen Proving Grounds
* [http://www.channelzilch.com/jack/dadwriting/coldfronts/cf_ch6.html "The Automated Weather Network" The USAF creates a real-time network of UNIVAC 418s]
* [http://vipclubmn.org/cp18bit.aspx 18-bit Computers - Computer Unit Tester, 1218 (CP-789), AN/UYK-5 Moonbeam, 1219B-CP-848/UYK , CP-914, ILAAS, 1819, AN/UYK-11(V)]
* [http://mccworkshop.com/computers/comphistory1.htm Article about the Univac 1219 and it's use in the Navy's Tartar Missile System]

Footnotes