Re: What Apple II cards used the $c800 ROM address space

[Rich <rich@dreher.NOSPAM.net>]

In article <f33567e7.0405191038.4ec6a81e@posting.google.com>, 
rdoerr@bizserve.com says...
> With the help of some others it appears that some of the trouble is
> that the SuperSerial card uses some ROM space at $c800 which from what
> I have been reading is bank switched and may also share that space
> with other I/O cards.  What other cards would use this area?  Does
> this sound correct or might I be looking in the wrong direction?
> 

Robert,

I am not sure I have the just of your question. But keep in mind that
many different cards use that space, including, for example, my CFFA 
card. The thing to keep in mind is that each card will have its $C800 to 
$CFFE address space enabled when any access to $Cn00 to $CnFF (PR#n code 
area) occurs, where n=slot number. That "Aux ROM" space will then stay 
active until either an access to $CFFF occurs or a system reset. Many 
card will actually decode the entire memory range, CF00 to CFFF as the 
Aux ROM reset area, to simplify the logic. Often you will see the 
instruction:
bit $CFFF
This disables the Aux ROM from the memory map.
When you do a Pr#n the system jumps to $Cn00 and begin execution. The
very first read is from Cn00, thereby enabling the Aux ROM space at 
$C800 if the card has one. Other example of cards with Aux ROM include:
SSC, most 80 columnc cards, most HD card including CFFA, etc.

I will leave it to others to speak about the emulator side of this 
question...

Rich Dreher