[Coco] OS9 floppy descriptor

[Robert Gault]

Chester A. Patterson wrote:
> I'm wracking my brain trying to remember how to modify a /D0_40D.dd or
> /D0_35S.dd to make a D0_80D.dd But my memory doesn't help me. I'm fed up
> with buggy floppies and going to move everything to 3.5"
> I've got OS9v2, ezgen 1.06, and some other tools, on the occasions when my
> current D0_40D doesn't give me read or CRC or any number of other errors.
> Help!
> 
> Thanks.
> 
> /Chester
> 
> 
> 

If you have the OS-9 owner's manual look at section 5, page 9. You 
download the NitrOS-9 project and use the 80 track descriptors that are 
part of the project.

If you have dmode (os-9 program to change descriptors) you can use it to 
alter any disk descriptor. Make sure that you cobble the boot disk or 
the change will be lost on reboot.

name    byte    size   function
IT.TYP   $16      1     device type
IT.CYL   $17      2     number of cylinders (tracks)
IT.SID   $19      1     number of sides

Currently IT.TYP for floppies should be:
* IT.TYP bit definitions if bit 7 of IT.TYP is clear (floppy disk)
TYP.5          equ       %00000000           5" media
TYP.3          equ       %00000001           3.5" media
TYP.SBO        equ       %00000010           Sector base offset (clear = 
0; sect = 1)
TYP.256        equ       %00000000           256 byte sector media
TYP.512        equ       %00000100           512 byte sector media
TYP.CCF        equ       %00100000           CoCo format
TYP.NCCF       equ       %00000000           Non-CoCo format