[Coco] CoCoSDC

[Robert Gault]

frase072 wrote:
> Robert,
> I'm looking for 256 to 512 mb for Nitros9 and the standard dsks for Rsdos. There is a utility in the Ultimate CoCoSDC image though I have to edit the program for more than the 128mb it creates. I played with that program today with good results. From within NitrOS9 I'll need to manipulate the device descriptor to make use of the extra space.
> I take it that the Rom location is the same for hdbdos and sdc dos?
> Doug
>
>

Far as I've been able to tell, there is no really good way to use a .vhd of the type used with MESS 
and VCC on the CocoSDC. That's because it seems there is no offset built into SDC-DOS and while 
YA-DOS does have an "fallback" offset in the ROM, it is not clear when it would be applied to a disk 
image and I have not gotten it to work.

What you can do is have two separate .vhd images stored on the CocoSDC. One is just NitrOS-9. The 
second is just 256 Basic disks. That is you break the normal .vhd into its two partitions.
When the Basic .vhd is mounted in the SDC slot0, SDC-DOS changes "drives" with DRIVE0,# where #=0-255.
I have built such a .vhd on my PC and copied it to the SDC uSD card. Access to any of the 256 drives 
works reasonably for most of my ml programs but it is not perfect. "Drives" can be changed for mount 
0 from an ml program by altering the value at $14E.

Now for your NitrOS-9 .vhd, you can change the /DD and /H0 descriptors. For example change cyl from 
$5A to $21C with dmode. Format your new .vhd, cobble it, and stock it with whatever you need. Just 
make sure the Os9boot file matches where you will mount the .vhd, Drivewire or the CocoSDC.

Experiment and report your results. :) If you want, we can work on this by private email.

Robert