[Coco] Need help with 3.5" drives and NitrOS-9

Gene Heskett gheskett at wdtv.com
Tue Dec 3 20:55:19 EST 2013


On Tuesday 03 December 2013 20:53:49 Robert Gault did opine:

> If anyone has a 3.5" drive attached to a Coco system please respond to
> this message.
> 
> Currently NitrOS-9 sets all descriptors for 80-track disks as 3.5" types
> with typ=$21. When such a disk is formatted, it is stated to be set to
> 135tpi.

This is wrong, in this case the descriptor portion of the makefile neds 
fixed, or the rbf.d(efs).
 
> Now if I try to read such a disk on my Coco3  with either a Tandy
> controller or a Disto SCII it will read correctly. However all writes
> to such a disk corrupt each byte usually forcing the msb high.
> If I use dmode to set typ=$20 for such a disk, format makes it a 48tpi
> disk and there are still 80 tracks. This type disk both reads and
> writes correctly on my system.
> 
> Clearly something is wrong. It does not seem to be my controllers and I
> don't see how it can be the 3.5" drive. The first question is does
> anyone else with 3.5" drives see a similar behavior. The second
> question is how should this be fixed? Is a Coco system just too slow to
> write 135tpi disks? Is perhaps the 3.5" drive on my Coco (MITSUMI model
> D35M3D) not capable of 135tpi writes? But then how can it read such a
> disk?
> 
> Apparently 3.5" disks can be formatted at 48tpi for 80tracks "double
> sided" and perhaps they should be for Coco systems. If that is the
> case, there should be some changes to one or all of rbf.d,
> rb1773desc.asm, and rb1773.asm in NitrOS-9.

Also correct.
> 
> Robert
> 
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Cheers, Gene
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