Now I have to decide whether the Dnepr-1 counts as 26 bits for my list ...
should parity/sign count?? Oh, and I was missing a 29-bit example ... so more
checking to do (you never know, it might have imagined it!)
On Tue, 29 Sep 2026, Paul Koning via cctalk wrote:
That's certainly a start but just the bare beginning. I suspect that, unti
lthe IBM/360, most machines had word lengths not a power of two. For example,
none of the DEC machines before the PDP-11. Older IBM machines had assorted
word sizes; CDC and Burroughs ditto. I worked on a 1970s era Philips machine
with 24 bits, and there were other minicomputer with that word length
(Modcomp?). Electrologica had 27 bit words. The MC research machines had word
lengths of 30 and 34 bits (the 34 bit one, ARMAC, was a successor of the 30 bit
ARRA 2 with a very similar instruction set, two instructions per word, but the
address space grew from 1k to 4k so the word was made 4 bits larger). ENIAC
was 40 bits I think.
I would count the sign since it's part of the data representation, but not the
parity bit. And on Burroughs mainframes the 3 tag bits are usually not
mentioned; if you do include them (sensible, since they carry semantic
information) you end up with a word size of 51 bits. Not often you run into
prime numbers for the word size.
In general, parity is not counted.
5150: 9 chips per row for "8 bit plus parity"
In 1982, I bought a 192K ecc memory board for 5150, from Boulder Creek
Systems (civic auditorium balcony of West coast computer Faire)
THAT was called "8 bit", but used TWELVE chips per row for Hamming ECC)
--
Grumpy Ol' Fred [email protected]
