[Coco] Dragon SuperDos and Drivewire....

[Aaron Wolfe]

On Thu, Oct 18, 2012 at 5:05 PM, Phill Harvey-Smith
<afra at aurigae.demon.co.uk> wrote:
> Hi All,
>
> Here's the problem, I'd like to try dropping the Drivewire routines into
> SuperDos, so that that DragonDos disks could be accessed via a Drivewire
> server.
>
> However at the lowest level I/O SuperDos deals with cylinders, heads and
> sectors, whereas DW is completely LBA based. Now SD does record the geometry
> of a disk in it's directory track, however this is track 20, this is of
> course read when a disk is first accessed as on a physical disk it is always
> in the same place c=20,h=0,s=1.
>
> With the standard emulator format files which used interleaved sides, this
> will mean for a double sided image that the directory track will be in a
> different position to the single sided image, which would be a problem.
>
> Is there a call in the currently existing DW protocol to get this
> information from the image ? Or to get the file data length of the image,
> even the max LBA sector number would give a hint.
>

The low level DW protocol does not have any kind of "tell me about
this disk" type of call.  Just sector read and sector write.
There is a high level API accessible over the virtual channels that
can tell you pretty much anything, image size, image format, etc.
However that is considerably more work to communicate with.

This isn't a problem in RSDOS i guess, since everything is 630 sectors disks.

So.. the only solution i can see in the current protocol is using the
high level API, and that would probably be a PITA from dos.  I an open
to adding a new low level 'disk info' type of call if this is the best
approach.  I can see how that might be useful in multiple situations,
especially now that DW has expanded to support Atari and Apple systems
as well, or even if we extended it on the CoCo to support 40 and 80
track disks.

I'm open to any ideas or anything I've missed, better ways to do it,
etc.  I am sure that we can support this one way or another, let's
just do it "right".

-Aaron