Re: DSK format specification

[pausch@saaf.se (Paul Schlyter)]

In article <lr0Qa.1241$dk4.53908@typhoon.sonic.net>,
Andy McFadden  <fadden@fadden.com> wrote:
 
> CiderPress looks for DOS, ProDOS, Pascal, CP/M, and RDOS filesystems in
> "DOS", "ProDOS", and "physical" sector ordering every time you open a
> disk image.  If the file has a helpful extension (like ".do"), it knows to
> try that first.  However, until it successfully identifies a filesystem, it
> can't know the sector ordering, which is why for disks with no recognizable
> filesystem (like games with custom loaders) it will ask you to choose one.
> Because sector 0 is always in the right place, finding a DOS 3.3 VTOC isn't
> sufficient... we know it's DOS 3.3, but we don't know what order the
> sectors are, so it's necessary to examine the rest of the catalog track.
> Which gets even more fun when you deal with 32-sector images on 800K disks.
> 
> Some formats, such as 2MG, are kind enough to tell you the order.  Others,
> like ShrinkIt, are always ProDOS-order.  In general, though, you have to
> keep poking at it until something looks familiar.
 
Then how do you determine the sector interleaving on a blank Apple CP/M
disk images (no files ever written to the disk, no CP/M system on the
system tracks)?  Such a disk will have all bytes in each and every
sector set to hex E5.  Perhaps in such a case you just assume DOS 3
sector order, since that's what works best with those Apple II emulators
which also emulates a Z80 ?
 
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