[Coco] noswiz doesn't work for me...

[gene heskett]

On Tuesday, February 14, 2012 05:23:20 PM Ciaran Anscomb did opine:

> Brett Gordon wrote:
> > CoCoBoot (and BASIC) is hanging on xroar anytime it writes to the
> > 0xff50-0xff57 region of the io space.  CoCoBoot is trying to find an
> > IDE harddrive there.   Xroar reports a "WD2793  bad command error".
> > I'm assuming xroar is putting a FDC controller there (rather than at
> > 0xff40 ?)
> 
> For RSDOS, I have A3 set = FDC IO, A3 clear = latches (drive select,
> etc.), with A0/A1 selecting the FDC register.  But I worked purely from
> schematics found on the web, I can't see anything to indicate that A4
> is used for addressing (so 0xff50-0xff5f will shadow 0xff40-0xff4f).
> 
> > It beleive this is the problem as CoCoBoot boots with
> > no problems without an IDE controller on a real CoCo2 or CoCo3, and on
> > Mess.   I'll keep dabbling an see if there's a work-around.
> 
> This implies there must be something going on though I'm not aware
> of - hmm!  Let us know if you find anything...
> 
This can happen I think, if the disk controller has a clock chip in the 
$ff50-5f area.  Of the packs I've had, Disto put theirs there, and I don't 
recall now where the B&B controllers put it but ISTR it was in the next 4 
address block above the controller itself.  It may be possible to set the 
TC^3 clock to that area too, so A4 is being used, but not well documented 
except in the individual controllers own documentation.

In fact, if ANY aftermarket stuff is in the system, assume A4 is being used 
since 95%  did a full decode, ignoring the broken (I'd like to break them & 
would have fun doing it) tandy decoding that wastes 8 times the i/o address 
space each device actually needs.

> ..ciaran
> 
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Cheers, Gene
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