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

[Luis Antoniosi (CoCoDemus)]

I,ve been using 1.44 drives without problems formatting to 720k. But it's
hell slow to format it.
 On 2013-12-03 6:56 PM, "Robert Gault" <robert.gault at att.net> wrote:

> 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.
>
> 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.
>
> Robert
>
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