Using Adapt912 as a BDM Pod with Adapt812MAX as a Target:

1. Make sure to reset Adapt812MAX with the jumpers set for single-chip mode (ie. MODA=MODB = 0)
2. Supply power to the target ('MAX) only-- the BDM will get it's power from the target.
3. Note that some register bits follow the rule "write anytime except the first time" in Special mode (ie. BDM active).  This means you have to enter the value again.

device 812a4
mm 0a 0c        (enter 0c againset expanded wide mode with LSTRB and R/W enabled)
0c    (second time to make it "take")
mm 0b f0        (set normal expanded wide mode)
f0    (second time to make it "take")
mm 3c 30    (enble both program and data memory Chip Selects)
mm 3d 10    (data memory covers lower half of memory map)
mm 7777 0    (you will now be able to modify external RAM locations)
bf 7000 7fff 55    (try filling a block of external RAM)

Note that other settings are possible for the registers, but the above are known working settings to get you started.