Issues with C128DCR - will not load games in C128 mode

[retrobecanes]

I recently acquired a C128DCR. It will boot any C64 games in C64 mode but freezes when trying to load C128 games in C128 mode. Sometimes I will hear the music of the game but nothing on the screen.
It will also freeze when trying to load CP/M for instance (will not get to a prompt).
Note that, for these tests, I am using an Ultimate II Plus cartridge set up as drive 8 (internal 1571 drive is disconnected).
I suspect a memory issue.
I typed the SRAM test program that I found on Ray Carlsen's page and it completed the test without reporting any error.
I have tried to make a C128DCR ROM that I found on World of Jani (modified C-128 DCR Integral Diag 1.0 (325109-01)), characters flash a few times on the screen and then nothing happens. Not sure that it is working correctly.
I am looking for advice on what to try next.

Thanks!

 

[ClassicHasClass]

Actually, this sounds more like a timing problem with the U2+. My 128DCR was more stable with setting Address valid after phi2 to at least 100. Obviously make sure the firmware is current as well.

 

[retrobecanes]

Actually, this sounds more like a timing problem with the U2+. My 128DCR was more stable with setting Address valid after phi2 to at least 100. Obviously make sure the firmware is current as well.

I will try that! That would be great news!

 

[retrobecanes]

@ClassicHasClass unfortunately none of the setting combinations worked on the U2+. The system is definitely sensitive to the Phi2 values, in some cases it would try to boot while with other values it would get stuck earlier. But in the end, I could not find a value combination that would make it boot a game in C128 mode. I keep trying to make one of those 128DCR diagnostic ROMs on either a 27128 or 27256 EPROM but none of them seem to work (a few flashing screens and then that's it). I also notice that none of the diag roms work in U36, I have to remove the ROM from U34 and place it there to see any effect. That doesn't seem to match anything I have read about those diag ROMs so far.

 

[retrobecanes]

Well problem resolved. All is actually working correctly. Although I disconnected all the wires from the internal 1571 drive in the C128DCR, it was still interfering with the UII+ set up as drive 8.
The system basically believed that it had two "8" devices and was getting confused when loading programs.
I ended up installing a hardware switch to swap the internal drive between devices 8 and 9 and now all is working well.