MOS 6509 Replacement Update

From: Jim Brain <brain_at_jbrain.com>
Date: Sun, 7 Oct 2018 23:44:56 -0500
Message-ID: <39849bf1-bfd8-652f-2ae8-d4959aeb05b1@jbrain.com>
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
      o upper 4 bits are exposed on pads/pins on the unit.
      o 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)
      o $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

-- 
Jim Brain
brain@jbrain.com
www.jbrain.com
Received on 2018-10-08 07:00:05

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