CMT 64Kb RAM module for HP-71b question

[mfleming]

(10-12-2021 05:17 PM)Sylvain Cote Wrote:  Note: at each module insertion and removal, the cycle ON+MEM+OFF were done twice to see if memory was stable and with the memory lost exception who happened once, it was.

Thanks for the test, I'll note this in some way for others who experience the same problem with stock configuration and application code.

Failure to remove the ROMs was the cause of the problem after all, just as J-F surmised. Turns out I failed to disable interrupts at the beginning of the RESETX handler. As a result, in the middle of RESETX processing, another command asserted on the bus caused control to be vectored to the command dispatch routine. And the band played on...

So by immediately disabling interrupts in the RESETX handler, RESETX code can finish. ROMs will be disabled and the MultiMod will go back to waiting for another configuration pass.

Timing is everything in this sort of control system!
~Mark