[fdutils] Need help with weird floppy issue

Simon Owen snowen at gmail.com
Tue Mar 7 00:50:42 CET 2006

On 3/6/06, Donnie Barnes <djbarnes at gmail.com> wrote:
> It's been reported that the floppy drive on the Sega machine *is* a
> standard PC drive, but I can't confirm that personally.  It is well known
> that using an actual Sega machine is the only way to copy a disk, too.  So
> in theory it is possible for a standard drive to do it, assuming that the
> reports of a normal PC drive working are correct.

It might only be an IBM-compatible format, so it works on a PC drive. 
The smaller format *can* be formatted on the PC, but it doesn't seem
possible for the larger one.  On a normal-spec 300rpm drive, the
standard 765 controller gaps add up to too much to format a track with
that layout.

It's a similar problem to 11-sector double-density Atari ST disks. 
The ST's WD1772 controller gives complete control of the track layout,
allowing gaps to be reduced to their legal minimum.  The PC only gives
control over gap3, which is the main spacing between sectors.  This
doesn't allow enough of a saving for 11-sectors to be formatted on the
PC, though existing disk can usually be read without trouble.

I'd guess that either the System24 board has a non-765 controller, or
the built-in drive is running slower than normal to increase the
capacity.  It should be possible to measure this with an existing disk
- I'll be in touch off the list... :-)

Best regards,


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