MOS 6509 Replacement Update

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MOS 6509 Replacement Update

Jim Brain

My apologies for the delay, but getting the B128 out for testing is arduous.

However, I have tested v4 of the PCB, with the following features:

  • Support for NMOS 6502, CMOS 65C02S, and CMOS 65C816S
  • Support for 4 or 8 bit PORT values
    • upper 4 bits are exposed on pads/pins on the unit.
    • system defaults to upper 4 bits masked to 0.  Sending special values to $0001 will enable/disable functionality
  • PORT reflects '816 bank in '816 native mode (currently untested, as I don't have sample '816 native mode code)
    • $0000/$0001 registers disappear in native mode
  • System passes test suite.

I have tested 3 CPUs here ('02, 'C02, and 'C816S) and all work, at least in emulation mode.  Rockwell 'C02 continues to not work, but I will leave that as an exercise for others.

Next steps:

  • Branch the code on github and put new HDL code up
  • Send working unit to Michal for additional testing/research.

If there is enough interest, I'll have a batch made.  Let me know off list.


Jim Brain
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