From: Ullrich von Bassewitz (uz_at_musoftware.de)
Date: 2002-11-20 14:05:44
Hi!
On Wed, Nov 20, 2002 at 12:23:49AM +0100, Andre Fachat wrote:
> yes indeed the PET kernal jump table at the end of kernal space is
> quite underdeveloped. In fact many useful jumps are missing as you
> state.
[...]
Thanks for all the help with this topic. In addition to the information
already posted here, I found out, that none of the routines in the kernal sets
the carry flag on error as the later models do. So if your code does something
like
jsr BSOUT
bcs error
you have a problem. My solution was to use full replacement routines that
read/write into the zeropage for
RDTIM
READST
SETLFS
SETNAM
Read $FFFB to detect the ROM version, then jump directly into the kernal for
OPEN
CLOSE
and add short wrappers that evaluate the status byte and set the carry flag
for
BSOUT
CHKIN
CKOUT
OPEN
CLOSE
According to the tests using VICE, my file routines work on all 3/4/8000 PETs
with these changes (the 2001 PET is not supported by cc65 anyway).
Regards
Uz
--
Ullrich von Bassewitz uz@musoftware.de
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