Applicard: the bug that came in from the cold

[Alex Freed <alex_news@mirrow.com>]

Those of you who replaced the RAM chip on my z80 board
with a 512K version need to know one important thing.

Steven already posted a message here describing a RAMDISK
bug he found. We were investigating it from both ends -
he was looking at the code and I tried to trace it with
my hardware toys.

Steve found that setting the size of extra memory to just
256K with a patch solves the problem. I have kind of traced
the code execution when there is no patch.

Looks like a logic error somewhere in code that never had
to deal with more than 256K of RAM. So the bug was dormant
for 20 years till I carelessly unleashed it upon mankind.

Bottom line: wait till Steve finds a real cure or do a
patch to limit the visible memory size.

Steve: could you please post the procedure here or even
better a disk image with the patch applied?

-Alex.