Amstrad diagnostics in fodos eprom question.

[solidhit]

Hello, I have built a fodos card and I have a 27256 EPROM which I want to populate with amstrad diagnostics. The questions are, which file do I put in the rom? Do I need to modify that file in any way? The eprom is 32K and diagnostics are 16K. Do I have to use something like DOS "copy /b file1.rom+file1.rom eprom.rom" and finally burn eprom.rom?

Would be grateful if I could receive some help.

[darkhalf]

Not familiar with that card, but AmstradDiagUpper.rom is needed
https://github.com/llopis/amstrad-diagnostics/releases

Normally 16K uses 27C128 EPROM but for 27C256 location of the ROM depends on A14 line, if connected to GND (lower bank) or VCC (upper bank)

Copying to both banks will work fine in either case like what you have written (or using a hex editor and copy/paste the image and save as 32K file)

[solidhit]

Thank you darkhalf for your quick response. I couldn't wait for an answer and did the obvious. Copied twice AmstradDiagLower.rom to a new rom file, programmed my EPROM and it worked first time! You see, FODOS was created years ago (before Amstrad Diagnostics) for a completely different reason, but since it activates the ROMDIS signal on the expansion port, it allows a specially made ROM like diagnostics to be the first piece of code the CPC will read upon boot. This makes it an indispensable tool to diagnose cases where the system ROMS or the first 64KB of RAM could be the issue! Anyway, thanks again, now perhaps I can diagnose a friend's CPC which doesn't boot properly.