I found my problem. A bug in my routine garbled parts of the ROM image as I
loaded it into memory. With that corrected, I can now see the routines
that access the 5710.
My earlier experiments with the drive memory are confirmed. The FDC has 2
extra registers at 2004-2005. The 6526 CIA is reduced to a serial port at
400C-400E, and there is an interface at 4010-4017. This interface appears
to be a floppy controller for the CP/M mode, based on the section of the
ROM that is different. Anyone want to try and figure out this interface
from the ROM routines? I think I'll pass on that one.
Notice that there are RAM shadows at 6000-7FFF. It takes extra logic
gates to make that happen. It is not due to incomplete address decoding.
Why is it there???
1571 C128D Drive
0000-07FF RAM 0000-07FF RAM
1800-180F 6522 VIA1 1800-180F 6522 VIA1
1C00-1COF 6522 VIA2 1C00-1COF 6522 VIA2
2000-2003 WD1770 FDC 2000-2005 5710 FDC
4000-400F 6526 CIA 400C-400E 5710 CIA Serial Port
4010-4017 5710 Unknown Interface
6000-7FFF RAM shadows
8000-FFFF ROM 8000-FFFF ROM
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