Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!wuarchive!psuvax1!psuvm!art100
From: ART100@psuvm.psu.edu (Andy Tefft)
Newsgroups: comp.sys.apple2
Subject: Re: Posting a series of questions for a friend.
Message-ID: <90283.163130ART100@psuvm.psu.edu>
Date: 10 Oct 90 20:31:30 GMT
References: <1990Oct10.004614.17496@cbnewsd.att.com>
Organization: Penn State University
Lines: 29

Re: Peripheral card expansion ROM space

This is from my old ][+ ref manual:

The 2k memory range from $c800 to $cfff is reserved for a
2k prom or rom on a peripheral card.

...

A peripheral card's 256-byte PROM can access the expansion ROM space
by referring to location $CFFF in its initialization subroutine.
[This causes all peripheral cards to disable their expansion ROMs.]
Of course, this will also disable the expansion ROM on the card which
is trying to grab the ROM space, but the ROM will be enabled again
when the microprocessor gets another instruction from the 256-byte
driving prom.

So, say you're looking at the card in slot 1. Look through $c100-$c1ff
for an rts (hopefully there will be one). Assume there's one at
$c143. Then just

    bit $cfff
    jmp $c143

and then you can disassemble from $c800-$cfff.

If you can't find an rts, a break will work, or any other instruction
that will cause a break and not a hang. I don't know which card's
PROM will be enabled in that space if you hit reset.