On 11/26/24 09:16, D. Hugh Redelmeier via talk wrote:
From: David Collier-Brown via talk <talk@gtalug.org>
Apparently at the moment, most RDIMM DDR5 is EC8 ECC which is 80bit. And most UDIMM is EC4 ECC which is 72 bit. I don't believe there is any requirement for it to be that way. Oh my goodness sake (;-))
That /really/ takes me back: I learned B on a DPS-8, which used 72-bit double-words. The DPS-8 surely had parity or ECC on top of the 72 data bits.
Yes, I vaguely remember that the raw data size was 80 bits, for ecc. It used to silently misbehave on misaligned fetches (:-(), but loudly complain about memory problems (:-)).
The DPS-8 was a 36-bit word system. A logical descendant of the IBM 701 (which had 72 Williams Tubes for RAM). Honeywell and UNIVAX hung on to 36-bits much longer than IBM.
(The first 36-bit word machine I used was an IBM 7040/44 but I only used FORTRAN on it.) --- Post to this mailing list talk@gtalug.org Unsubscribe from this mailing list https://gtalug.org/mailman/listinfo/talk
-- David Collier-Brown, | Always do right. This will gratify System Programmer and Author | some people and astonish the rest davecb@spamcop.net | -- Mark Twain