On Sun, 21 Aug 2022 at 16:04, Stephen Adolph <[email protected]> wrote:
> I guess I got the polarity wrong regarding A*. > > Well, > > I guess try what you like. In my tests, A* seems durable to output > shorting. I think I read the buffer datasheet to see what the output short > current is. Anyhow you see the issues. > > I think the only way you see that there is a PSU discontinuity coming is > by monitoring /RAMRST. Which makes it hard if you are back driving it. > One could do it with a current monitor of some kind, maybe > > in M100 CP/M, the BIOS makes extensive use of the M100 main ROM. If you > disable and replace with RAM, you'd need to replicate all of that ROMware > to support CP/M. > > Doable for sure. Why not just replace the optrom with RAM? leave the > main ROM alone. > > The scenarios that drive the need for ram protection > 1) battery runs out (or any other discontinuity) and PSU shuts down via > TRAP > 2) user hits reset > 3) program inadvertently shuts off the PSU (kinda the same as 1) > Thanks for your insights, Stephen! I'll play with the options. It might take a while (too many projects :)), but if I run into issues or have progress to show, I'll report back to the list. Cheers, Henner.
