8" hard sectored floppies

From: Fred Cisin <cisin_at_xenosoft.com>
Date: Thu Jun 3 17:40:35 2004

> > >Hard and Soft sectored disks are never compatible.
On Thu, 3 Jun 2004, Tom Jennings wrote:
> > Ah, never say never, my friend! ;-)
> I believe the ubiquituous NEC 765 (et al) does its "index" on read by
> scanning for the 0th sector ID (which is 1 :-) The index hole is only
> needed for formatting, and that only for compatiblity.

Unfortunately, the 765 does a "reset" of the chip whenever it sees the
index. It can handle NOT having an index hole (AFTER formatting),
but excess holes will keep it from working.

Apple (and Commodore and Atari 400 series?) did not HAVE an index sensor,
therefore, they could use diskettes that were intended to be hard or soft
sectored, and could do flippy diskettes if the write-protect were
circumvented.

OB_stupid-project:
I once modified a 5.25" drive to index on the hub, instead of the
photocell. Then I didn't need to punch the jacket for doing "flippy"
diskettes on single sided formats. It also meant that I could flip over a
hard-sectored diskette and format it. That made a diskette that could be
used and its contents copied to a "normal" diskette with COPY or DISKCOPY,
but COPYII-PC (including OPTION BOARD) would choke on trying to copy it.
But,... the Teac 55 series drives wouldn't work with it, since they rely
on seeing an index hole within a reasonable time period to beleive that
the drive is "ready".
Received on Thu Jun 03 2004 - 17:40:35 BST