[Coco] OS-9 Level I v2.0 hard disk image how-to?

[rick ulland]

Good question with many levels. Physical CoCo, a descriptor identifies 
tracks/heads/etc, and the driver applies those settings to 'an 
controller'. If you have an OS9 driver, and you are not going to attach 
a physical disk, 'dmode' any legal descriptor settings and nobody 
cares.  As a really old guy, no idea how to format a virtual disk for 
the hardware that isn't there, but I hope this starts a convo.

-ricku

CoNect

On 10/8/2022 4:34 PM, Robert "Exile In Paradise" Murphey via Coco wrote:
> If I wanted to emulate a CoCo 2 with the 15 or 35MB Tandy hard disks,
> how could I do it?
>
> The OS9 Level 1 v2.0 addendum says the Tandy hard disks are:
>
> 15MB uses 6 heads, 306 cylinders, 345 tracks per inch, 32 sectors per
> track and 128 pre-comp.
>
> 35MB uses 8 heads, 512 cylinders, 512 tracks per inch, 34 sectors per
> track and 256 pre-comp.
>
> The two options I know of up front to format a disk image are:
> Toolshed os9 tool
> MAME imgtool
>
> MAME imgtool does not let me specify enough heads or cylinders, and my
> suspicious is that the field is 8-bit anyway so the numbers given won't
> work.
>
> os9 let's me create an image with the same total logical sectors, but
> the geometry doesn't match up and I don't know if that would stump the
> driver or if I need to create a different device descripter.
>
> So, I am reaching out to see if anyone has any tips on how to simulate
> the original 15M or 35M hard disk on OS9 Level I v2.0 for a CoCo 2...
> using emulators or hardware with the CoCoSDC attached.
>