From: Spiro Trikaliotis (ml-cbmhackers_at_trikaliotis.net)
Date: 2004-07-03 18:40:03
Hello,
sorry for the late reply.
* On Wed, Jun 23, 2004 at 11:57:51AM -0400 Greg King wrote:
> From: Spiro Trikaliotis; on Date: Monday, June 21, 2004, at 01:00 PM
> > I modified the UNLISTEN routine (c64) in the following way:
[...]
> > One remark: The C64 crashed after this test, but I don't think this
> > is very important here.
>
> That is because you put RTS in the place of PLA, so the stack was
> "unbalanced."
Yes, obviously. Thanks for pointing this out.
> I have an idea: change the command-code (the $3F at $EDFF) that
> UNLISTEN sends. The C64 will do everything else normally. The drive
> will see something, but it will not think, "I must stop listenning."
To what should this be changed? This byte will be sent with active ATN,
thus the floppy will interpret it. Regardless which command you sent
(other than LISTEN itself), the floppy will perform an UNLISTEN
afterwards (at least, the 1541 behaves this way. Look at the ROM code).
Regards,
Spiro.
--
Spiro R. Trikaliotis
http://www.trikaliotis.net/
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