[Coco] Re: NitrOS9 on MESS?

[tim lindner]

Nathan Woods <npwoods at cybercom.net> wrote:

> Roger Taylor writes: 
> 
> > At least you know that it's occuring while RBF is writing out to a
> > storage device.  So if this does not happen on a real CoCo, and the code
> > is  exactly the same, then it's M.E.S.S... probably a timing issue or the
> > index hole signal code.  ??
> 
> Truthfully, I do not know.  This particular bug defied almost all of my
> assumptions.  At first, I assumed that it was either a FDC timing bug or a
> 6309 core bug.  However in my investigations, it seems that the orders to
> write to the bad sector come from outside cc3disk.  The fact that the bug
> occurs when used with a VHD - thus bypassing cc3disk - confirms this 
> observation.  Since this bug also occurs with NitrOS-9 6809, the 6309 core
> is not to blame. 
> 
> Generally any bug that appears in MESS but not the real hardware is by
> definition, a MESS bug.  Probably the only bugs for which this is not the
> case is if some CoCo code was relying on something totally whacked out, such
> as reading from undefined IO memory or the contents of memory when power is
> turned on.  I'm inclined to believe that the latter is not the case.  It
> could be a timing bug, but what kind of timing bug would cause this bug.  As
> for "index hole signal code", can you elaborate on what that is?

I have not been able to reproduce this bug under MacMESS.

Maybe it is a compiler bug. MacMESS compiled with Metrowerks Codewarrior
6.2 or 6.3 has this bug:

http://bugzilla.mess.org/show_bug.cgi?id=316

But when it is compiled with GCC/Project Builder it runs fine.

Also, why hasen't this bug made it into Bugzilla?

-- 
tim lindner
tlindner at ix.netcom.com                                        Bright