Re: Disk images-- ShrinkIt .sdk on dsk's

[Rubywand <rubywand@swbell.net>]

"Mr.I'mAnOutOfControlLisaSimpsonFannnn" writes ...
> 
> >    It is unfortunate that the original choice of the suffix for A2 emu
> > disk image does not promote recognition of disk order. The ending
> > ".dsk" conveys the idea of "disk image", not "DOS 3.3 disk image".
> > The ending ".po" looks like a subset of ".dsk" rather than an 
> > equal-level category.
> 
> There was a .do ending, as well as .po and .dsk.

     Yes; but, it is virtually never used-- probably just as well.

 
> .dsk might have meant either ProDOS order or DOS order, while .do and .po
> were more specific.

     AppleWin works like that. If a disk image file name ends with ".dsk",
AppleWin will figure out the sector ordering (i.e. it will identify DOS 3.3
or ProDOS ordering).

     If the name ends with ".po", then AppleWin assumes ProDOS sector
ordering (which means the disk will bomb if it is not really ProDOS sector
ordered).  The same principle applies to names ending with ".do".

     The problem with this approach is that sector ordering is important
information. Many users like to transfer disk image files using ADT and ADT
does not correctly transfer ProDOS ordered images. There is no place in an
archive for a "whatever order" name designation.

     So, although ".dsk" _can_ indicate either DOS 3.3 or ProDOS sector
ordering (at least to an emulator), the standard is to use ".dsk" for just
DOS ordered images. 

     Since a 5.25" ProDOS formatted disk with ProDOS content can be a DOS 3.3
ordered disk image, it turns out that there is nearly zero need for 5.25"
ProDOS disk image ordering. In general, when a 5.25" disk image is created
using DSK2FILE or Asimov, the disk ordering should be set to "DOS 3.3" and
the file name should end with ".dsk".

     About the only exception to the above seems to be when a disk image is
produced from a ShrinkIt 5.25" disk archive (.sdk) file, usually via Nulib on
a PC. These disk images end up with ProDOS sector ordering and need a file
name ending with ".po".



Rubywand