Xerox 820 system disks in Teledisk format?

[Richard Lynch]

On 5/8/09 6:14 PM, "Steven Hirsch" <snhirsch at gmail.com> wrote:

> Back to the original subject:
> 
> I have IMD chugging away merrily on the Compaticard and, thanks to some
> advice from Dave, can use it as the secondary controller.
> 
> Now, I'm trying to figure out how to format a SSDD diskette for the Xerox.
> They use a screwy format where track 0 is FM 128 bytes/sector (26 x 128)
> and all the others are MFM 256 bytes/sector (26 x 256).
> 
> Is there a way I can kludge through this with IMD?  Or, do the Xerox
> system utilities actually reformat track 0 when you sysgen (in which case,
> it really doesn't matter what track 0 is configured as)?
> 
> Steve
> 
> 
Of the 100 or so Xerox floppies I've archived so far, track 0 varies enough
that my guess is it doesn't matter.  I've seen a lot of 26x128 as you
mention, but every once in awhile it is 26x256, and sometimes the interleave
matches the rest of the tracks and sometimes it doesn't.  When the disk is
DSDD, track 0 side 1 always matches the rest of the tracks at 26x256, even
if side 0 is 26x128.  When I use IMDV to look at track 0, sometimes it's
completely blank and sometimes not.
Richard