IEEE-488 bugs with BASIC 1 (was Re: PET2001-2316-board with 2532 / 2716 possible?)

classic Classic list List threaded Threaded
3 messages Options
Reply | Threaded
Open this post in threaded view
|

IEEE-488 bugs with BASIC 1 (was Re: PET2001-2316-board with 2532 / 2716 possible?)

Ethan Dicks
On Tue, Apr 18, 2017 at 6:33 PM, William Levak <[hidden email]> wrote:
> 6540-020 is for BASIC 2.  No version of BASIC 1 will use the floppy drive.

I recall all the notice back in the day that the BASIC 1 ROMs worked
with the first dot matrix printer released for the PET (CBM 2022) and
not the 2040 floppy drive, but does anyone know the specific issue?

I'm slightly curious about what it might take to "bake in" replacement
IEEE routines for a program for which one had source to call "fixed"
routines not the buggy ones in ROM.  These routines would look largely
like what's already in the BASIC 2 ROMs, I'd figure, but for now, I
really just want to know what the bug(s) was/were.

If that's covered in Raeto West's book or somewhere equally
accessible, I'm happy to just get pointed at the literature.

Thanks,

-ethan

       Message was sent through the cbm-hackers mailing list
Reply | Threaded
Open this post in threaded view
|

Re: IEEE-488 bugs with BASIC 1 (was Re: PET2001-2316-board with 2532 / 2716 possible?)

André Fachat

Am 19. April 2017 02:57:45 schrieb Ethan Dicks <[hidden email]>:

> like what's already in the BASIC 2 ROMs, I'd figure, but for now, I
> really just want to know what the bug(s) was/were.

> If that's covered in Raeto West's book or somewhere equally
> accessible, I'm happy to just get pointed at the literature.

I don't remember the details, but I once created a "fix" for the BASIC 1
ROMs for the VICE emulator.
The fix is optionally patched into the ROMs to make the IEEE488 disk
routine work - VICE xpet does not use ROM traps but real hardware emulation
for the IEEE488 bus so I could not just move traps around.
A quick look into the xpet directory of the VICE source should suffice to
find it.

For a real machine another mail triggered something deep in my memory I saw
when I designed my replacement board. It might indeed be possible that the
EOF line conflicts with a video line (sync?) on one of the ports. It could
be that for the upgrade you may have to cut a wire too. But maybe someone
with real upgrade experience may chime in here.
And/or having a deeper look at the schematics...

Regards
André

>        Message was sent through the cbm-hackers mailing list



       Message was sent through the cbm-hackers mailing list
Reply | Threaded
Open this post in threaded view
|

Re: IEEE-488 bugs with BASIC 1 (was Re: PET2001-2316-board with 2532 / 2716 possible?)

Rhialto
On Wed 19 Apr 2017 at 07:10:51 +0200, André Fachat wrote:
> It might indeed be possible that the
> EOF line conflicts with a video line (sync?) on one of the ports.

This is what I remember: the screen blanking line interferes with the
EOI line. Which would not be so bad by itself, but the screen is blanked
during scrolling, to prevent the "scrolling snow" because the RAMs are
too slow for concurrent video and CPU access. Later versions wait until
vblank time (or maybe it did that already as well, I now realize), which
slowed scrolling down so much that people start to use the "fast print
poke". The one that was rumoured to be able to damage your hardware.

-Olaf.
--
___ Olaf 'Rhialto' Seibert  -- Wayland: Those who don't understand X
\X/ rhialto/at/xs4all.nl    -- are condemned to reinvent it. Poorly.

signature.asc (465 bytes) Download Attachment