8-inch disk drives

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Thu Jul 24 16:24:00 2003

> Tony wrote
> > I am wondering how on earth you can make a disk controller (note, not the
> > OS driver software, the physical controller) that works correctly with a
> > 9-sector-per-track format, but fails with the 8 sector-per-track version,
> > all other parameters being the same. Because that's the only difference
> > between the 320K and 360K MS-DOS formats.
>
> Only if you were to make an "intelligent"* controller that was designed to
> work as a sort of co-processor with less interaction with the main system.

OK... I'll bet that no normal PC motherboard uses such a controller,
though...

I have found PC disk controllers that can't handle 360K disks. When used
in 1.2M (360rpm drives), such disks have an effective 300kbps data rate,
which the (broken-as-designed) controller didn't handle. I complained
about this, only to be told that 'nobody uses 360K disks any more'.
Hmmm... It claimed to be 'IBM compatible', and the IBM controller
certainly handles 360K disks...

-tony
Received on Thu Jul 24 2003 - 16:24:00 BST