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Old June 29th 03, 05:24 AM
Grant Edwards
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In article , Everett M. Greene wrote:

IIRC, the Navy's UYK-44 processor (probably UYK-20 as well,
though I'm not sure it did FP) also used base 16 for the
exponent, so increasing the exponent by 1 shifted the mantissa
by 4. I dare anybody to claim that's a useful bit of
information to have retained for 15+ years....

I think I've actually read about this, once. Been a while,
though. And... I'm glad I was able to forget it. Now, you've
gone and forced those poor brain cells to re-align on this and
I'm probably going to forget something else important.


Could be worse, I could've explained what BAM variables were...


BAM is neat!

BTW: Wasn't it AYK-20?

-20 didn't have any FP. I've never been hear a -44.


I _think_ it was UYK, since everybody prounouced it "yuck".

The 44 was a small version of the same architecture that was
done by, um, Sperry (I think). Originally it was designed for
use on submarines (A 44 chassis would fit (barely) through a
submarine's loading hatch). A '20, OTOH, was more of a
standard computer-room VAX-sized thing -- you'd have to build a
sub hull around it.

A '44 consisted of a backplane full of very expensive little
boards (about 3x6 inches). It took several of the boards for
the CPU, and then there were memory and I/O modules. The whole
thing, including power supply was the size of a small suitcase.
The CPU was built out of AM2901 bit-slice processors, and
executed a superset of the 20's instruction set.

The '44 was "standardized" as the Navy's official embedded
computer. It was about as powerful as decent 8086
single-board-computer, only 100X larger and 1000X more
expensive. It did have plug in cards for all the oddball
USN-specific serial/parallel interfaces, which gave it a leg-up
on commercial stuff. The '44 had FP, and the ones I played with
used EEPROM/RAM instead of core (though core memory was
available for it, IIRC). It was sort of cool that it could do
polar-rectangular coordinate transforms in a single machine
instruction.

For the project I worked on, we would have embedded a couple
8086's and done C programs given our 'druthers, but NAVSEA
insisted that we use '44s and write in CMS/2 or CMS-2 or
whatever it was called. The also wanted us to use some OS or
other from the '20. But, there was no way it could deal with
the real-time requirements we had, so they let us write out own
simple kernel.

The whole project was cancelled after a couple years (never
even got a prototype working). A few years later it was revived
and redesigned using "commercial" processors before being
cancelled again.

Sure glad I'm out of defense work...

--
Grant Edwards grante Yow! My forehead feels
at like a PACKAGE of moist
visi.com CRANBERRIES in a remote
FRENCH OUTPOST!!