Re: Commodore 2031LP and Zoomfloppy

Hi Spiro,

On Mittwoch, 30. Mai 2018 23:19:42 CEST Spiro Trikaliotis wrote:
> Hello André,
> 
> * On Tue, May 29, 2018 at 10:18:21PM +0200 afachat@gmx.de wrote:
> > The converted 1541 would give, after reset, a correct status, but a detect
> > command would result in a message like
> > 
> >   8: *unknown*, footprint=<F@NJ>
> > 
> > however the footprint number is actually changing from detect to detect.
> 
> The "unknown" is to be expected (as the footprint is not known).
> However, the footprint should be stable. As it is not, it is a sign that
> there is a communication problem.

Indeed this seems to be the case.

.... 
> That's interesting, because this results in some (simple) text-like
> answer. Perhaps, the floppy answers with some error message? "0,"
> indicates that it might be an output like on the error channel,

This is exactly what seems to be happening. I added some debug output to 
xum1541.c, to see what data is actually transferred on the host side, and saw 
that the result always looked like part of a status message, sometimes even 
just from the 00, OK,00,00
 
> Thus, it seems we have a severe communication problem. As the 2031 is so
> similar to the 154x, I am sure that the commands must be interpreted the
> same as there. Thus, I can rule out command differences, and it must be
> a communication problem.

I am currently looking at the transition from SecListen to Bsout - it seems to 
me that there is something going horribly wrong.

> Especially the C@BL --> "0," is interesting, it might be part of a
> "30,SYNTAX ERROR..." message from the floppy!
> 
> I see that Ethan had to DOB@ more oftern, which indicates "O " text, but
> also the C@BL which indicates the "0,".
> 
> > The 2031LP also was giving strange errors on detection. After drive power
> > up, status gives the correct message, but detect also returns a similar
> > message to the one above.
> 
> That's interesting. "status" does not perform much communication from ZF
> to the floppy. It justs send a TALK, and then the floppy has to talk.

This side of the communication seems to work reliably. 
 
> The detect, on the other hand, has to send a M-R command to the floppy
> in order to operate.
> 
> That might be an indication that the communication from the 2031 to the
> ZF works, but the other way, there are problems.
> 
> Can you execute the following commands:
> 
> cbmctrl reset; sleep 5; for ((I=1; I<20; I++)); do cbmctrl status; done
> 
> Does the status look good in all cases? Does the communication stop at
> some point of time?

The command you wrote executes completely as expected. It just shows the drive 
status 20 times, from the first "73,cbm dos v2.6 2031,00,00" to 19 following 
"00, ok,00,00".

> > Interesting. It seems either the 2031 has a problem with the IEEE488
> > protocol of the zoomfloppy, or something is different with I guess M-R
> > with which the ROM is read (and the drive type detected?)
> 
> Exactly, it is M-R that is read. However, looking at the ROM code, the
> 2031 does not differ at all in the implementation of M-R from the 154x.
> If there were problems, I would have expected them for the 1001, as the
> implementation might differ.

Yes, I currently also suspect the IEEE 488 communication.

Regards,
André