[Coco] hybrid CoCo-CP/M disk

[Willard Goosey]

>From: "Darren A." <darccml at hotmail.com>
>Date: Mon, 15 Jan 2007 10:14:39 -0700
>
>This is a good point. If you wish to be compatible with third-party versions 
>of Disk Basic, then you should probably exclude CP/M from touching any part 
>of track 17. 

Yes, that was a typo.  My CoCo "partition" starts at track 17, it
doesn't end there.

>You *may* also need to be concerned about marking tracks 35-39 as
>alllocated, since most third-party versions support 40
>tracks. 

I thought about that, and I do sometimes use Chris Hawk's MyDOS, but
since this is more a private exercise than something I'd distribute, I
decided not not bother.

>However, I would imagine that they must put some information
>somewhere on Track 17 to indicate if the disk is not a standard 35
>track Shack format.

I don't know about any of the others (third party Disk BASICs) but
MyDOS doesn't, directly.  Indirectly, you can look for granule numbers
larger than 68 in the FAT, or for a FAT more than 68 bytes long.  The
problem with determining the lenght of the FAT is that that sector is
zero-filled -- when you find a 0x00 is that the end of the FAT, or
just a granule who's next granule is granule 0?
 
>Of course, with a third-party Basic that supports double-sided 40 track 
>disks, you could make a hybrid disk with most of side 0 (except track 17) 
>devoted to CP/M, and side 1 available for Disk Basic!

>From what I've seen, the double-sided BASIC formats treat each side as
a completely seperate disk.

Willard
-- 
Willard Goosey  goosey at sdc.org
Socorro, New Mexico, USA
"I've never been to Contempt!  Isn't that somewhere in New Mexico?"
   --- Yacko