[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Volume Number support for .dsk images



I considered posting this fact, and you are quite correct.

However, I'm not sure how useful that would be, as if the app uses it's own access routines, nothing requires the volume in the sector headers (which is what they will see) to be (IIRC) the one's complement of the VTOC volume--or even for the DOS 3.3 data structures to be valid.

Does anyone know if either is the case for the examples Rubywand posted?

In the cause,

David S.

noone@nowhere.net wrote:
Rubywand wrote:
>Like emu writers don't have enough to do, here's another wish list item: Why not add support for Volume Numbering of .dsk images?

And don't forget as was pointed out earlier, it is embedded in the VTOC on track 11, sector 0, Byte 6 on DOS 3.3 diskettes... No file name convention required. (ProDOS is always the same volume number, 1, I think.)

Look for pattern "04 xx xx 03 xx xx ##", ignore the xx bytes and use the ## number for the volume when reporting to DOS.

Thankx,
Ed

Extra info taken form the FAQ about the VTOC on a DOS 3.3 diskette...

Track 11, Sector 0:
Byte   Meaning
----   -------
$00    Unused (always $04 on my disks)
$01-02 Track/Sector location of first catalog sector-- the standard
       location is Track $11/Sector $0F (17/15)
       Note: The location of first catalog sector may be different on some
       disks. DOS 3.3 can adjust; but, some utilities (e.g. Copy II Plus)
       assume T/S $11/$0F and will not be able to find the catalog.
$03    DOS version number ($03 for DOS 3.3)
$04-05 Unused
$06    Volume Number-- $01-$FE (1-254) is the standard range;
       $FE (254) is the standard default VN
       Note: This entry merely records the VN for handy reference.
       VN is set when a disk is INITed and it is embedded in the
       Address header of each sector.
$07-26 Unused


--
"Good judgment comes from experience, and experience comes from bad judgment." --Barry LePatner