[Coco] Dmode Settings

Stephen H. Fischer SFischer1 at Mindspring.com
Mon Jun 4 17:56:26 EDT 2012


You are right and wrong.

Yes as to the storing of the sectors so the double step that OS-9 uses on a 
physical drive to read a 48 TPI disk in a 96 TPI drive will not work.

Wrong as the DD.FMT in LSN0 of the .dsk file must match DNS in the device 

There may be other fields in LSN0 that are checked / used.

DD.FMT bit 0 =1 means the floppy image is double sided, DNS=1 will read a 
single sided disk if DD.FMT says the floppy is single sided. (More OS-9 

It takes carefully reading of at least three pages in the OS-9 RBF section 
and a bit of thinking and much more typing to explain that I wish to do 


----- Original Message ----- 
From: "Aaron Wolfe" <aawolfe at gmail.com
To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
Sent: Monday, June 04, 2012 1:45 PM
Subject: Re: [Coco] Dmode Settings

> FWIW, a .dsk file is simply the sector data arranged in LSN order.
> Physical attributes such as tracks, cylinders, sides have no meaning and
> are not part of the dsk format at all, they are neither stored in the .dsk
> file nor are the used in any way by software reading a .dsk file.

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