Univac History & Commentary
Queen City Software
423 Walnut Street
Harrisburg, Pennsylvania 17101-1908
If you thought SkyGlobe (one of the world's top public domain
downloads) was spectacular, wait until you get a load of PC/1100!
We KNOW most of you downloaded SkyGlobe simply because it was an
excellent realtime graphics program that filled your hi-
resolution screen with lots of pretty dots. How many of you
actually USED SkyGlobe for skywatching or astronomy?
Well, PC/1100 is equally useless and twice as spectacular. You
can program it. You can actually use it to do 36-bit and 72-bit
computations. You can learn how to program in genuine Univac
1100 Series assembly language with it (if anyone cares anymore).
It is a true-to-life mainframe emulator that gives you a
fullscreen high-resolution color graphics display of a REAL
Univac 1100/40 console -- the most spectacular CPU console ever
designed. It fills the screen with more than a dozen ever-
changing 41-bit registers (36 data bits; 5 parity bits) and
numerous system registers, not to mention backlit pushbutton
controls. (Don't forget to press F4 to start the light show!)
The measurements for each individual console component were
obtained from actual photographs and are faithfully translated to
your PC's screen as well as today's video technology allows.
Actually, PC/1100 was designed for use in teaching and learning
Univac 1100/2200 Series assembly language, which is a rather
esoteric field. Unisys' USIS Education Division thumbed their
noses at it when it was offered to them for sale, so now you're
getting it for FREE, just to spite them. Their official reply
was, "...we believe we have sufficient tools in our suite of
teaching aids.". Yeah. Sufficiently BORING tools...enough to
dissuade anyone from learning and using assembly language.
Have any of you actually SEEN an IBM System/360 or System/370
console in operation? Well, Sperry/Univac put them all to shame
with the Univac 1100/40 IOAU/CAU console, which is depicted in
all its glory by PC/1100.
Most people have never even heard of the Univac 1100 Series of
large-scale mainframe computers. This is because IBM stole the
commercial limelight, whereas Univac is quietly -- but
extensively -- used by governments worldwide. (The New Zealand
Navy has a Univac, of all people.) Few commercial enterprises
have had a need for the large-scale data processing power
available from a Univac 1100 or Unisys 2200. IBMs suit their
miniscule needs quite well, although a mid-size Unisys 2200 could
do so much better. There is no such thing as a small-scale
A Univac 1108 (2nd generation transistorized circuitry) EASILY
outperformed the entire line of IBM System/360s (3rd generation
integrated circuitry) -- with the sole exception of the 360/95
(only two of which were ever built, and one of which was utilized
by NASA at Goddard Space Flight Center to control the Apollo
space flight missions).
To many government data processing employees, Univac is
synonymous with pride, pleasure, and nostalgia. After all, the
alternative of *I*B*M* is too much to stomach.
IBM = Incredibly Big Monopoly
UNIVAC = UNIversal VACuum tube corporation of america
UNISYS = UNited Insolvent SYStems, inc.
Another favorite of mine is UNIBLAB -- the tattle-tale robot from
"The Jetsons" cartoon series. I frequently refer to Univacs as
Uniblabs, because virtually every system and user activity on a
Univac is logged to disk or tape for security reasons. (Univac
was doing this long before "WarGames" hit the silver screen or
security-lax IBM ever bothered.)
Back in the 1940s, when the ENIAC was built, computers were a
chaos of rack-mounted circuitry. Then, Eckert & Mauchly designed
and built the neatly-packaged Univac I for the U.S. Census Bureau
(presently on display in the Smithsonian Institution's Museum of
Science and Technology). Incidentally, the Census Bureau STILL
uses Univac/Unisys equipment quite extensively.
The Univac I looks like a cross between something from a Wyle E.
Coyote blueprint and a 1950s ad depicting a 21st Century "Washing
Machine of the Future". BUT IT IS BEAUTIFUL! (See UNIVAC-I.DOC
for information on our plans for a Univac I emulator to
complement PC/1100.) I wish I could see one in full operation.
Around 1965, IBM came out with the most commercially successful
mainframe to-date -- the 3rd generation System/360. The higher
the model number, the more buttons, switches, and flashing lights
it had. Very impressive, especially considering the source.
Then, IBM spoiled the light show with its high-end System/370
consoles. Plain old monochrome CRTs with light pens. The main
console for a System 370/158 had only 4 measley buttons!
Never again will we see rows and rows of fascinating colored
lights that flicker on and off so fast that no human can possibly
know what they signify. (Remember the movie "Colossus: The
Button and light dissipation has even taken its toll in the PC
world. The good ole Altairs -- and especially the IMSAI 8080
(the "WarGames" PC that Matthew Broderick had in his bedroom) --
at least had 2 or 3 full 8-bit LED register displays on the front
panel. Now, we're lucky to have a power indicator and functional
hard disk access LED!
Many of you (including long-term Univac veterans and users) may
wonder what ever prompted Univac's 36-bit word (instead of the
more intuitive 32-bit word). The reasoning is based upon archaic
compass-needle thinking (360 degrees) rather than pure binary
logic. It has to do with even word divisibility:
36 = 36*1 (whole-word)
36 = 18*2 (half-word)
36 = 12*3 (third-word)
36 = 9*4 (quarter-word)
36 = 6*6 (sixth-word)
Univac characters were (and still are, in some places) 6 bits
each. The 6-bit Univac character set is officially called
"Fieldata". With it, you can represent the entire alphanumeric
character set [A..Z,0..9] and still have room left over for 27
symbols and the
field communications use, hence the term Fieldata.
This made great sense in the old days when nobody cared about
upper vs. lower case, especially when one considers that ancient
FORTRAN utilized 6-character identifiers and labels. Thus, the
Univac can fetch and do comparisons on FORTRAN identifiers in a
single machine instruction.
Unisys STILL uses a single 36-bit instruction word. There is no
such thing as a variable-length instruction in the Univac world.
One instruction -- one word -- one fetch. Period. This makes
dump-busting infinitely easier than in the IBM 360/370 world, and
accounts for the major reason that I hate IBM and to this day
still haven't been able to figure out how to program in BAL
(Basic Assembly Language)!
Sadly, all of the Univac 1100/40s have apparently been scrapped
by now. I spoke with several mainframe computer salvage experts,
all of whom said they haven't even seen one at the scrap yards
for many years now.
There are still numerous Univac 1100/80s (the last of the
spectacular Univac mainframe dinosaurs) in service, including at
least 6 at the IRS Service Center in Martinsburg, WV. The
1100/80 panel, however, was dedicated to multiprocessor hardware
partitioning, so there wasn't much in the way of blinking lights
on it, except for the F0 register, which was for some reason
So, now we are left with mainframes that don't even have a single
backlit power switch. The light show is over, and the only place
left that you can see one is here in PC/1100.
This version of PC/1100 is hereby dedicated to the public domain
in an effort to preserve and add to our nation's rich computing
David William Nixon
Queen City Software