Format for IBM display writer disks??

From: Wayne M. Smith <wmsmith_at_earthlink.net>
Date: Thu Jan 18 23:44:22 2001

> On Thu, 18 Jan 2001, Wayne M. Smith wrote:
>
> > My S/23 Service Manual states that two 8 inch
drives
> > were available, the 31SD which was a single sided
FM
> > only drive, and the 51TDF which was a double sided
FM
> > or MFM drive. The disks have 77 tracks per side,
and
> > data can be written on tracks 1 through 74, with 00
> > reserved for labeling and 75 and 76 for
replacement.
> >
> > Both drives are hard sectored. FM disks can be
> > formatted with 8, 15 or 26 tracks, with 512, 256
and
> > 128 bytes per track respectively. For MFM the
bytes
> > per sector are doubled.
>
> I believe that you mean SOFT sectored, as the number
of sectors
> per track in a hard sector disk is determined by the
disk and
> is only changeable by using a disk with a different
hole pattern.
> FYI, 5.25" disks came in both 10 and 16 sector hole
patterns,
> while 8" were 32 hole only to the best of my
knowledge.
>
> - don

My S/23 manual says the following:

"The location of the access hole for index sensing on a
diskette [type] 1 differs from that on a diskette
[type] 2 and diskette [type] 2D." The 31SD drive can
only read type 1, so I guess you could say it's soft
sectored (I assume it ignores the hole). The 51TD
reads types 2 and 2d, which have the same hole pattern
vis-a-vis each other, but different from a type 1, but
also reads type 1. It distinguishes based on the
location of the index hole, so I would say it was hard
sectored. Then again, in effect it's only determining
DS vs. SS so maybe that's not the same thing. What do
you think?
Received on Thu Jan 18 2001 - 23:44:22 GMT