After posting a few inquisitions on practicalmachinist.com and cnczone.com (major cnc related forums), without a single response at all I felt a bit discouraged. But to quote someone special; "When I get sad, I stop being sad and be awesome instead".
So now I have dragged out all the cards from the M1 computer and started probing them for intel (pun intended). It looks as though the card with the reset button at the back, called "R3D415000", or "Datacontroller" is the culprit.
|Unfortunately none of my cameras are operational at the moment, so only a stolen picture.
It features among other things the following IC chips:
- 1 x Intel P8088 L6100335 <-- CPU
- 1 x Intel D8259A L4057497 <-- PIC for 8080 architecture
- 4 x Hitachi HM6264LP-15 <-- 64Kbit Static RAM (battery backed)
- 4 x Intel D27256 <-- 256Kbit UV Erasible NMOS EPROM
- 1 x YUASA Sealed Ni-Cd battery 3-51FT-C 3-5V 50mAh
I have also ordered a cheap eprom programmer that supposedly handles the 27256 chips on this card. The plan is to read them in and look at the code (should be in x86 machine code, which there are lots of tools for). If I want to fiddle with it, I can probably write the possibly updated changes to more modern eeprom chips of the same spec that go into the sockets on the card. If I get anywhere with this, I will try to patch the code so that I can run my own subroutines attached to button clicks on one of the inert buttons in the display (there are at least two buttons with no symbol on them, that I guess are just legacy/future-proofing).