I made a PCB for Grant Searle's Z80 CP/M computer.
https://github.com/profdc9/Z80SBCI have had a problem I can not figure out. When I turn on and reset the computer from a cold start after not having applied the power for awhile, the computer seems to operate just fine. I can boot up CP/M and use it for about 2 or 3 minutes. However, after 2 or 3 minutes, CP/M starts to show BDos errors and directories appear with duplicated filenames. Shortly afterwards, the computer stops accepting serial input, though if I reset serial output occurs (it displays the "Press [SPACE] to activate console").
I have removed the compactflash card and all of the chips I added to the design and the problem still happens. I thought it might be that I was using the Z80A DART, so I bought a Z80B DART, but that did not help.
If I unplug the computer and allow it to stay unplugged for a few minutes, the computer is fine again for a few minutes. Maybe its a heat problem, but none of the chips get more than slightly warm.
If anyone could provide advice on how to track down such an intermittent problem I would appreciate it. The schematic for the Z80 computer is in the github project.
Thanks!