I'm trying to understand exactly why various chips were designed the way they were at different times, in the service of which I have a rather specific question:

When did MOS Technology upgrade to 5µm process technology?

According to a source quoted from https://en.wikipedia.org/wiki/MOS_Technology_6502 "The first 6502 was fabricated with 8 micron technology"; that would have been in 1975.

According to a comment in Limiting factor on sprite sizes "VIC-II and amiga OCS chipset were both using 5um technology" so they reached that process node no later than 1982.

So presumably it was sometime between 1975 and 1982 they got the upgrade to 5µm, but which year?

  • 1
    Not a particularly useful answer, but 8um to 5um is somewhere between 1 and 2 standard process steps, so Moore's law suggests it should have been before 1978. Although that is, of course, only true on average.
    – Jules
    Commented Aug 28, 2018 at 11:18

1 Answer 1


Having found more datasheets, I’m going to push back the date I originally gave. The first major upgrade to the 650x line, probably representing a process upgrade, was to increase the speed from 1MHz in 1975 to to 2MHz, announced as “Preliminary” in May 1976. MOS made available the 3MHz models of its line no later than March 1980.

This site claims that, in 1984, MOS was manufacturing the 7501 in “HMOS-I” (which would be 3.5µm) and the 8501 in “HMOS-II” (2µm), implying that MOS had gone at least two steps past 5µm by 1984.

Therefore, MOS built its 8µm fab in 1974 and probably upgraded its CPU manufacturing from 8µm to 5µm in late 1976, which was three years after HP and around the same time as Intel. (Or perhaps there was another step along the way?) It apparently then upgraded to a HMOS-I process in 1980 and HMOS-2 in 1984, so approximately once every four years.

  • Interesting data point! Do we know which process node that was an upgrade to? I did not expect the upgrade to 5um to come so late, but it could've been for all I know.
    – rwallace
    Commented Sep 6, 2018 at 3:49
  • 1
    Your link indicates that they were using 5µm for the Amiga chipset in 1982. It does not, however, directly say.
    – Davislor
    Commented Sep 6, 2018 at 3:51
  • 1
    @rwallace You were right; it probably was several years earlier than I initially thought.
    – Davislor
    Commented Sep 6, 2018 at 9:03

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