From: Marko Mäkelä (marko.makela_at_hut.fi)
Date: 2004-05-26 18:24:18
On Wed, May 26, 2004 at 09:14:00AM -0500, Jim Brain wrote:
> True, my command can be repeated:
>
> LISTEN 4
> LISTEN 5
> LISTEN 8
> etc.
True. I confused your LISTEN directive with the LISTEN command of the
serial bus. But I still think that it's cleaner to list all device numbers
in a single atomic command.
> I'm still trying to decipher your protocol. How does it deal with a
> resynchronization of the serial line (to prevent interpreting commands
> as data or vice versa?
In my protocol, $00 is the escape command. A $00 data byte is escaped
as $00 $00. If an ATN interrupt arrives, it'll send some $00 xx escape
(see the comments). There are also $00 xx responses for indicating EOI,
end of ATN transmission, or talk-attention turn around.
> I also want to support higher level commands (get file, let the AVR deal
> with the IEC commands)
I didn't want to do that, because I thought you would need a custom
application on the other end of the serial line anyway. Besides, the
Flash ROM of the 2313 was getting a little tight (especially if support
for burst mode transfers or JiffyDOS is going to be added later). It
would be a different matter if all protocols for the cassette port were
removed. Of course, as you have a bigger controller, the design constraints
are different.
> I've got routines working, and I have a state diagram (had to generate
> one for my state machine in the AVR.
Could you represent the diagram in an easily editable format? I'd start
with the input language of GraphViz, but maybe someone knows a better
approach that has been implemented in an open source or free software tool.
Marko
Message was sent through the cbm-hackers mailing list
Archive generated by hypermail pre-2.1.8.