From Computer History Wiki
Revision as of 16:27, 8 April 2021 by Tor (talk | contribs) (Re - microcode)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search

Another meaning

"Microprocessor" also meant "microcoded processor" in some circles. I have seen it used about the Alto and MAXC processors, so maybe it was a PARC thing. If those two examples are all I can find, I will not bring it up any more. Larsbrinkhoff (talk) 20:56, 7 April 2021 (CEST)

Hunh. I have never heard that one; I've always heard the term 'microcoded' for that. I wouldn't mind listing it as 'rare second meaning', if you think it's desirable. Jnc (talk) 21:57, 7 April 2021 (CEST)
Thanks. I think I'd like to see at least one occurrence outside Xerox PARC for it to be worthwhile. Larsbrinkhoff (talk) 07:39, 8 April 2021 (CEST)
The term "microprocessor" was sometimes used to describe the unit that decoded the microcode in CPUs designed before the arrival of the "microprocessor" as we know it. I had a look on a couple of manuals for the NORD-10 (1973) and the term is occasionally used there (and that's presumably why it's also used in the page linked here on the Wiki, which was originally from Wikipedia in its earliest form). The concept of using microcode for a processor was something I believe the designers of the NORD-10 brought over from the US, and presumably they brought the terminology as well. When I checked the documentation for the later ND-100 (1979), a compatible, slightly larger system with newer technology, the term 'microprocessor' was only used to describe the bit-slice units used, not the microcode decoder. This was of course after the "modern" microprocessor CPU had been introduced. Tor (talk) 09:52, 8 April 2021 (CEST)
Ok, that counts as one more occurrence! Larsbrinkhoff (talk) 10:19, 8 April 2021 (CEST)
You say "brought over from the US"? Did one of the designers of the NORD-10 have some contact with a US project which used microcode? I ask because the concept of microcode is generally attributed to Wilkes (in "The Best Way to Design an Automatic Calculating Machine", 1951, re-printed in The Early British Computer Conferences, MIT Press, 1989); although he used the term "micro-operation" and "micro-programming", the term 'microcode' seems to have been a later (albeit obvious) formulation. Although Whirlwind used an early form of microcode - without the conditional branching (which seems to have been Wilkes' idea; he mentioned it in the 1951 note). Jnc (talk) 13:27, 8 April 2021 (CEST)
That was only speculation on my part. One of the engineers at ND visited MIT as a student, and brought ideas back - although the most important part was probably about always looking for the latest semiconductor technology). But the first ND, the NORD-1, was not microcoded. The second major revision, the NORD-10, was (but otherwise the architecture was quite similar, and compatible). Tor (talk) 16:27, 8 April 2021 (CEST)