[sebhc] Quick note on my favorite topic - Floppy Formats

Dave Dunfield dave04a at dunfield.com
Tue Jun 1 04:48:19 CDT 2004

At 23:35 31/05/2004, you wrote:
>Question for Dave or someone who has used his emulator more
>than I:
>   - how important is the "volume number" for a diskette?
>As we get the floppy format issue settled, we'll probably
>need to store the volume number in the image header. 
>However, I've never really cared much about the volume
>number...but someone might.
>The way an H17 HS disk is formated, the volume number is
>in the sector header.  For track 0, this number is always
>0.  For the remaining tracks, it is the volume number of
>the floppy.

This is perhaps a weakness in the emulator's drive emulation.
I made the decision NOT to include the sector headers in the
drive data file - the file contains only the 256 byte data portion
of each sector - this is consistant with the drive images which
are posted on the SEBHC site.

The emulator really does not care about the drive volume number.
It needs to know it so that it can generate appropriate sector
headers above track zero - to do this, it reads sector 9 when
the diskette is mounted.

[I'll bet this is one reason why INIT doesn't work - I don't
 currently accept data for sector headers, and would therefore
 not return the right volume id after an init - I'll have to
 check into this]

dave04a (at)    Dave Dunfield
dunfield (dot)  Firmware development services & tools: www.dunfield.com
com             Vintage computing equipment collector.

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