19 Jan
2001
19 Jan
'01
12:53 a.m.
On Thu, 18 Jan 2001, Wayne M. Smith wrote:
of sectors
Wayne, what they are discussing is the aperture in the disk
jacket that permits seeing the index and/or sector holes.
On the Single-Sided disks that aperture is 7degrees clockwise
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 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? from 12 0'clock. On the Double-Sided disks it is
26 degrees
clockwise. Double-Side drives have sensors in both positions
and can therefore read either single or double sided disks.
On the other hand, Single-Side drives have only a single sensor
at the 7 degree position.
In a Hard-Sector 8" disk there are 32 evenly spaced sector holes,
plus 1 index hole that is centered between two of the sector holes.
To all intents and purposes, the only difference between a single
and double sided Hard-Sector disks is the location of the aperture.
- don