[Coco] Questions about CoCoSDC, RBSUPER, and LLCOCOSDC

[Tormod Volden]

Robert,

Look in level1/modules/rbsuper.asm and search for AddSectorOffset -
this is where the sector offset, specified in the descriptor as
IT.SOFF, is added.

It certainly makes sense that such an offset is defined in a
descriptor, and not in the driver code.

I actually use this on the SD cards for the MOOH, the cards have a
normal DOS partition table (GPT partition table is also supported in
FUZIX!) and I place the NitrOS-9 partition at sector #512 of the card,
with the corresponding IT.SOFF set in the device descriptor (from
superdesc.asm).

Regards,
Tormod


On Mon, Apr 29, 2019 at 9:56 PM Robert Gault wrote:
>
>   I'm not sure if this is the right place to ask these questions but here goes.

Where else? :)

>
>   I have a CoCoSDC running the latest SDC-DOS (1.6 CC3) and HDB-DOS (1.4) for the CoCoSDC. I'd like
> to use as a .vhd drive the same type that is used with MESS and VCC. So far, what I have seen on the
> Internet are either the Basic partition of 256 "drives" or the OS-9 partition not both on one vhd
> for the CoCoSDC.
>   Now I have been able to mount a copy of my VCC .vhd on the CoCoSDC and with a copy of the T34 and
> OS9Boot file from a CoCoSDC drive in "drive" #255 been able to auto-start HDB-DOS and from a menu
> boot NitrOS-9 just as I would with the VCC.
>
>   What I have not been able to do is, while running NitrOS-9, access an OS-9 formatted disk in the
> Basic partition. Looking at the source code for rbsuper and llcocosdc, I can see that rbsuper uses
> bit 3 in DNS as an "HDBDOS" flag and STP as a virtual drive number when the HDBDOS flag is set.
>   So with dmode /SD1 drv=0 dns=8 stp=$FF I ought to be able to read the "drive" #255 in the Basic
> partition of the .vhd drive on the CoCoSDC. It does not work.
>
>   I can see in rbsuper.asm where the calculations are done to offset by 630 sectors per STP value
> but don't see anywhere that an offset of $5A000 is added. That might be the problem if the Basic
> partition offset is not defined anywhere for rbsuper.
>
>   Boisy, Darren, or anyone else who has played with rbsuper, and llcocosdc, I'd love some comments.
> Should rbsuper or llcocosdc be changed? With emulators, the offsets are calculated in VEmuDsk, the
> low level driver. However, as rbsuper is doing most of the calcs, perhaps $5A000 should be defined
> and added in rbsuper.
>
> Robert