Denton Gentry wrote:

>   I have a few questions:

I can only attempt an answer at one. :-)

> 1) Is that upper bit (0x8000) some kind of flag bit rather than
>    part of the offset?

Most likely. The older ROMs (up through the IIcx, I think) used
several (2 or 3?) of the high bits as locking and purgeable bits,
I believe. The "32-bit clean" ROMs don't do this. Of course, I
would expect that this would cause some cards to fail on the Mac 
II, IIx and IIcx. Perhaps it's only for SE/30 internal video.

	--John