[Coco] DriveWire

[Robert Gault]

Steven Hirsch wrote:
> On Fri, 6 Mar 2009, Robert Gault wrote:
> 
>>> Forgive my possible forgetfulness and my lack of understanding...But 
>>> how do you use a physical system and a drivewire system together on a 
>>> real Coco
> 
>> Well you can't do both simultaneously. That is you can access either 
>> the PC hard drive or the Coco hard drive.
> 
> ?? Why not?  I use DriveWire on my CoCo 3 alongside an IDE hard disk and 
> a floppy.  This is under OS-9.
> 
> 

Your comparing apples and oranges. Boisy might explain this better but 
here goes.

Under OS-9, there should be two drivers on the boot disk one for the IDE 
and one for DriveWire. That means when you try to access your Coco IDE 
drive, the signal flows through an interface/controller in your MPI. 
When you try to access your PC, the signal flows through the bit-banger 
port via DriveWire.
Under Disk Basic HDBDOS, there is not room in ROM for more than one 
driver. It will be one of the following, scsi, ide, or DriveWire. (Boisy 
may have found a way to fit both scsi and ide.) So there is no way to 
access both a ide hard drive and a PC .vhd drive from a single ROM image 
under Disk Basic. You can access the floppies on the Coco while HDBDOS 
accesses the  PC for drives 4 and up but that is a different issue.