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    840AV boot issue

    Thanks! @Arbee do you know where to find the detailed IO mapping? the only thing I was able to find is the generic Apple documentation that says "reserved to Apple" for that segment (and the replicas). BTW: last night I had a look at the data bus during the repeated read cycles and found...
  2. G

    840AV boot issue

    probed address and control signals on the 68040. CPU keeps reading at address 0x50F2A100 now. based on PST0-3 (traces below together with /TS and /TA) it keeps running the same instructions in supervisor mode (PST3=1, PST2=0). Probably the program does not like what it is reading. It will be...
  3. G

    840AV boot issue

    Typo, address is actually 0x52F22106, so in the I/O space.
  4. G

    840AV boot issue

    I decided to go back to my old 840AV after ~20years. Similar to other stories I read on this site: powers up, no chime, checkerboard video, no boot. Re-capped, probed supplies: all fine, probed some of the '040 pins. It seems the CPU runs for ~30" (see R/W trace below) then stops. The address on...
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