[Coco] DriveWire

[Boisy Pitre]

On Mar 7, 2009, at 8:38 AM, Robert Gault wrote:

> 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.


Right.  Just to clarify Steve, you can do this under NitrOS-9 because  
of the extensible nature of the OS and its access to memory  
resources.  On the Disk BASIC side, under HDB-DOS, it's:

	FLOPPY AND (IDE OR SCSI OR DriveWire)

Someone (Frank?) posted the other day a wishlist, one item being using  
all these devices under HDB-DOS at once.  It cannot be done under the  
current ROM size limitations that we have to work with, or without  
expanding the syntax of the existing HDB-DOS commands.

Burke & Burke's Hyper-IO was the closest I've ever seen to a Disk  
BASIC environment having access to different types of devices like  
OS-9 gives you.

Regards,
Boisy G. Pitre
--
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