Re: Memory Emulator (was ASBX code is AMXY)

["John S. Gwynne" <jsg@jsgpc.mrcday.com>]

|   4. Replace the EPROM on the MemCal with NVRAM (Dallas chip?)

not likely without adding more logic or modifying the board to send
the Memcal read/write/enable control. There was a big discussion of
this back when the list first started... along with other emulation
technologies... worth read once the archives are backup on the website.

The '730 had provisions for an extra RAM chip that makes adding NVRAM
in place of the EPROM easy... on the main PCB not the MEMCAL. I
started out with wanting to do it on the MEMCAL too, but it didn't
take long ohming out traces to see the board modification was much
easier. My ECM has only two visible external modifications; two
switches... one two disable NVRAM writes, the other to switch between
EPROM and NVRAM. On the PCB, I stood-off the NVRAM chip in the extra
RAM's location.... All but 6-8 pins aligned. A few wires, and it was
done.  Ok... maybe not that easy... but close...


| So, that's the theory! Now I'm off to modify my ASBX/AMXY, etc. code

I've been running my '730 that way for about a year now without
failure. The axxc bin that I have made available
<ftp://jsgpc.mrcday.com/pub/gmecm/axxc.S_032000> has my ALDL
modifications; ALDL mode 11. This modification will let you modify any
address with the engine running or not. I would hope that this is a
good starting point for other bins with similar ECM boards.

john gwynne
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