tbray@watsol.UUCP (07/19/87)
Roy Smith asked about ' a machine with a 24 bit word '. At one point GE made a line of such computers, called GEPAC. They were aimed at process control applicatins, and they had a couple at a steel company where I worked. They ran off a real live drum. Which reminds me of one of my favorite war stories. The infamous old IBM 1130 was basically a 16-bit machine. For double precision it used this *6-byte* ones-complement datum from *hell*. While I was a hapless young DEC software services type, I had to write a subroutine which would convert such a beast to a VAX double. When you do something like this, you realise you really don't understand anything about bit ordering or excess whatever notation. (Consider what can happen to numbers of the form -1 * (2**n) in a one's complement mantissa). Anyhow, three days of MACRO 32 hacking later, I and the customer were happy. Problem was, the reason we were doing this was to convert 10 zillion numbers from old financials on tape. When the accountants saw that all the historical figures were out by a penny or two for large dollar values, the you know what hit the you know what. (Hey, you go from 6 to 8 bytes, change notation and FP formatting routines and see if the pennies come out right). Never did find out how it ended.
bobw@wdl1.UUCP (Robert Lee Wilson Jr.) (07/22/87)
CDC made a 24 bit machine (I think it was model 924) which was basically one half of a 1604 which used 48 bits and was their first machine. The 924 used the same PC cards, same core planes, etc. It never had much commercial sale, but I believe it was used on some naval craft, possibly nuclear subs of the day. That machine must have come out about 1961 +/- two years. Harris Computer Systems grew out of the old Datacraft, whose machines were all 24 bits. Some contemporary Harris machines are still 24/48 bits (some 48 bit paths, some 24 bit registers and operations.)
mac@uvacs.CS.VIRGINIA.EDU (Alex Colvin) (07/24/87)
Sometime back in the 60s, the Navy spec'd out a machine (a UYK?). They'd figured out exactly how much they needed, and came up with a 19-bit word. Some outfit named DDP designed it, called it the DDP-19. Fortunately, it was never built. Now the reason some of y'all ought to know this is becasue of what became of it. The company was bought by Honeywell. The (least significant) 3 bits were lopped off, and it became the Honeywell 116. Later enhanced into the 316, 516 and 716. All defunct. Some folks ran away with the 516 and formed Pr1me. You can still see it in the instruction set, the one with X and Y and little else.