[Coco] Using DS disks on JV emulator

[Robert Gault]

I've found that only one of these items needs adjustment on my system and that
is the DD.FMT byte on LSN0 of the disk. Changing that from double to single
sided (bit0=0) is the only change needed to read the disk. The other changes
should only be needed to create such a disk with Format.

There is one big caveat with this procedure. The disk still won't be bootable
nor will it be usable under Disk Basic. If you want the disk to boot OS-9, you
will need one more type of boot module added to the list. The new module needs
to look for the kernel not at t34s1 or LSN264 but t68s1 or LSN4C8.

Bob Devries wrote:
> 
> Jeff Vavasour's emulator *can* be made to use double-sided disk images with
> a small amount of effort.
> 
> 1. Make sure the image has a .dsk extension (of course)
> 2. Use DMODE to set the drive descriptor to:
> 2.1 DNS=3 (96 tpi if the image is a 80 track DS disk) or:
> 2.2 DNS=1 (48 tpi if the image is a 40 track DS disk)
> 2.3 CYL= Set this to TWICE the number of tracks,
>       i.e. $00a0 (160) for 80 track, and $0050 (80) for 40 track
> 2.4 SID=2 (set to two for now, will be changed later)
> 3 Insert the disk in the drive (use the F2 key)
> 4 Use DED to change the byte at offset $10 (16 decimal) to ONE LESS than
> what's there.
>    E.g. $07 becomes $06 for 96 tpi disks, $03 becomes $02 for 48 tpi disks.
> 5 Write the mods to the disk, and exit DED.
> 6 Use DMODE to change SID=1
> 
> Voila! you can now read the image.
> Comments and questions welcome. Complaints to /NIL :-)
> 
> Regards, Bob Devries; Ipswich, Queensland, Australia
> 
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