[Coco] DriveWire - test results using the now free code

[Robert Gault]

Here are some results of testing DriveWire3 on a Coco3 without burning 
an EPROM. Since I already have a SCSI system, I put the ROM image on my 
hard drive in LOADM format. The preamble loads the ROM at $3000. There 
is also a short binary to move the ROM to $C000-$DFFF, overwriting my 
SCSI DOS with HDBDOS for DriveWire3.

I was able to read any Basic .dsk image on my PC from my Coco. Initially 
I was not able to read any of the virtual Disk Basic disks on a .vhd 
image, although part of the OS-9 section was displayed.

Normal RGBDOS or HDBDOS contains an offset in ROM to indicate the start 
of the Basic partition of a hard drive. This offset is at $D938-$D93A. 
Looking at the DriveWire3 ROM at this location found that the offset is 
set to $000000. That make complete sense when trying to read a floppy or 
a hard drive which has no OS-9 partition.
OK, so after booting DriveWire3, I POKEd the value $5A000 into the ROM 
offset location. This value is the default for most .vhd drives that 
have an OS-9 partition and it is the default offset value in RGBDOS for 
Coco emulators.
Now after mounting a .vhd image in the DriveWire3 Win server, I was able 
to read the Basic drives on the PC from my Coco. The system behaved 
exactly like running RGBDOS in VCC or MESS.

As soon as Boisy posts the NitrOS-9 boot disk for DriveWire3, I expect 
it to work just as well as the above. I should be able to put the boot 
disk on my Coco hard drive system, and boot into NitrOS-9 on a .vhd 
drive on the PC.
Probably I will also be able to put the boot disk on a Basic drive of 
the .vhd image and after starting HDBDOS as above, boot NitrOS-9 on the 
PC without having any OS-9 code at the Coco end.