[Coco] disk drive/controller formatting question

[Robert Gault]

Whichever way it works and doesn't work, Disk Basic and OS-9 
(particularly NitrOS-9) seem to require different amounts of precision 
from the drives. OS-9 on my system is much more sensitive to rpm than 
Disk Basic. With the latest NitrOS-9, we (Boisy's crew) have found some 
hardware won't format a disk at 2MHz and have changed the code so that 
the Coco slows down during format. Earlier versions of NitrOS-9 stay at 
2MHz.

Keep in mind that the interleave value can be changed in both Disk Basic 
and OS-9. So, if you think that may be the critical parameter, try 
formatting disks with a different value. Larger values of interleave may 
be easier for the drive. Values larger than 3 or 4 should not make any 
difference.

Do both drives have this problem? Have the drive speeds been checked 
either with software or with the strobe markings? Are the head slides in 
the drives clean?

Bob Devries wrote:
> Arrgh. gremlins struck.
> 
> I meant to say that formatting under OS9 works fine.
> I remember that OS9 uses a different interleave for floppies, but would that
> make the difference?
> 
> ----- Original Message -----
> From: "Bob Devries" <bdevries at gil.com.au>
> To: "Cocolist" <coco at maltedmedia.com>
> Sent: Wednesday, August 24, 2005 4:09 PM
> Subject: [Coco] disk drive/controller formatting question
> 
> 
> OK, guys, a curly question:
> 
> Brian has a FD-500 controller with two Matsushita JA-551 drives. He can read
> disks no problem, but formatting fails at track 17. This is under Disk
> Basic.
> HOWEVER, formatting under disk basic works fine!
> What is different about the OS9 formatting that it will format disks ok, but
> disk basic won't? He's using standard Radio Shack issued OS9 Level 2.
> 
> Any clues?
> 
> --
> Regards, Bob Devries, Dalby, Queensland, Australia
> 
> Isaiah 50:4 The sovereign Lord has given me
> the capacity to be his spokesman,
> so that I know how to help the weary.
> 
> 
> 
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