[Coco] Virtual disk file formats

[Barry Nelson]

The emudisk driver allows access to a imaginary hard disk controller on VCC and MESS. The need for a single disk image is because VCC only support drive 0 on the emudisk interface. MESS supports drives 0 and 1, but that is still only two drives. DriveWire using the becker port on the emulator, or the serial port on the hardware supports many drives.

> Tormod Volden lists.tormod at gmail.com 
> Thu Feb 18 12:40:33 EST 2016
> 
> On Thu, Feb 18, 2016 at 5:48 PM, Robert Gault wrote:
> > You can now access all the 256 Basic drives but will not have access to the
> > OS-9 portion of the .vhd as it is filled with $00. So you will need to use a
> > distribution disk that can access an emu type drives so you can format the
> > OS-9 portion of the .vhd disk.
> > You will need the eumdsk driver and descriptor to access the .vhd from VCC
> > or MESS. Format the .vhd which will be /H0, and fill the CMDS directory with
> > the current commands.
> 
> Just an innocent question, why is an emudsk (emulator disk?) driver
> needed? Doesn't the emulator emulate normal disks? Or is it just a way
> of "cheating" because normal disk drives are so complex to emulate and
> we don't really care enough?
> 
> Also why this seemingly complex and confusing topic of combining an
> HDBDOS portion and NitrOS-9 portion on one disk image. I understand
> when having one real hard drive used for everything. But for emulators
> or DriveWire, isn't it easier to use several disks? For instance when
> using DriveWire I have a NitrOS-9 disk image in slot 0 and a HDBDOS
> image in slot 1.
> 
> Regards,
> Tormod