Hey,
I accidentally left my CX5MII on and unattended for an hour or two, and when I got back it was in full sunlight and had gotten really hot. So I quickly shut it off.
However when I restarted it a little later, DMS2 no longer worked! It gave weird sounds when booting and crashes. Also when I unloaded DMS2 from the MegaFlashROM SCC+ SD 512k, it seems to work fine at first but booted in MSX-DOS 1 in stead of MSX-DOS 2. And when I tried _MUSIC it gives me a blue screen with full white background and then crashes, and _FMV just crashes without any feedback.
Because MegaFlashROM SD didn’t boot in MSX-DOS 2 mode any more, my first suspect was the memory mapper. And indeed, this is the result of a test:
10 ? PEEK(&H8800) 20 POKE &HC800,47 30 ? PEEK(&H8800) run 255 47 Ok
Also after OUT &HFE,1
or any other value, the result is the same. And when I e.g. do OUT &HFF,3
, it should crash because I swap out the system memory, but nothing happens.
Finally, the result of INP(&HA8)
is 240 (11110000B), so the internal RAM in slot 3 is selected, apparently the CX5MII’s (modified) MSX1 BIOS does not search for RAM otherwise it would’ve picked the RAM in the MegaFlashROM.
So now that we’ve established the internal memory mapper is busted, can someone help me figure out how to find out which component is damaged and how to replace it?
p.s. The CX5MII service manual is here if you need to take a peek.