[Coco] Help with Jeff V. Coco3 dos emulator

[Robert Gault]

One other point about the JVC series. The Collyer updates for the Coco3 to 6309 
also work with .vhd hard drives exactly as MESS and VCC do.

Because of the problems with double sided disks, NitrOS-9 users really should 
use a 35-track single sided boot disk on an RGBDOS .vhd image with NitrOS-9 
installed on the .vhd.

I've not been able to get RGBDOS or .vhd drives to work with the Keil emulator.

Robert