17 Jan
2001
17 Jan
'01
4:26 a.m.
Does anyone know what disks format the IBM Display writer uses?
Joe
17 Jan
17 Jan
8:29 a.m.
On Wed, 17 Jan 2001, Joe wrote:
Does anyone know what disks format the IBM Display
writer uses?
It is a bit of an oddball, Joe - 8" SSSD, but with 256 byte SD
sectors. At the moment, I cannot tell you how many per track. There
may possibly be a DS version, but I have no information on that aside
from an oblique hint that it might exist.
I think that I have some around here - if I can resurrect them - if more
information is important.
- don
18 Jan
18 Jan
2:43 a.m.
Don,
Thanks for the info. It's not that important. I found a new sealed box
of Displaywriter disks from IBM and was just wondering what format they
were. I'm guessing that these may be double density since the the boxed is
marked "2D" inside of a circle.
Joe
At 11:29 AM 1/17/01 -0800, you wrote:
On Wed, 17 Jan 2001, Joe wrote:
Does anyone know what disks format the IBM
Display writer uses?
It is a bit of an oddball, Joe - 8" SSSD, but with 256 byte SD
sectors. At the moment, I cannot tell you how many per track. There
may possibly be a DS version, but I have no information on that aside
from an oblique hint that it might exist.
I think that I have some around here - if I can resurrect them - if more
information is important.
- don
17 Jan
17 Jan
10:29 a.m.
I was told that it was the same as the System 36, and possibly 23 also.
We were talking about that when be got an old IBM disk archiver. I
haven't looked into it any further than that, though.
On Wed, 17 Jan 2001, Joe wrote:
Does anyone know what disks format the IBM Display
writer uses?
Joe
M. K. Peirce
Rhode Island Computer Museum, Inc.
215 Shady Lea Road,
North Kingstown, RI 02852
"Casta est qui nemo rogavit."
- Ovid
9:54 p.m.
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.
Using 256 bytes per sector, this gives you from 284K to
985K per floppy depending on drive/floppy type. This
data corresponds exactly to the data on the
displaywriter disk drive found at :
http://home.planet.nl/~tresmont/ibm-hall.htm
Therefore, I think must use the same format. For what
it's worth, the displaywriter disk drive looks almost
identical to the 5246 unit that goes with the S/23.
-W
I was told that it was the same as the System 36, and
possibly 23 also.
We were talking about that when be got an old IBM
disk archiver. I
haven't looked into it any further than that,
though.
On Wed, 17 Jan 2001, Joe wrote:
> Does anyone know what disks format the IBM
Display writer uses?
>
> Joe
>
18 Jan
18 Jan
8:56 a.m.
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
Using 256 bytes per sector, this gives you from 284K
to
985K per floppy depending on drive/floppy type. This
data corresponds exactly to the data on the
displaywriter disk drive found at :
http://home.planet.nl/~tresmont/ibm-hall.htm
Therefore, I think must use the same format. For what
it's worth, the displaywriter disk drive looks almost
identical to the 5246 unit that goes with the S/23.
-W
I was told that it was the same as the System 36,
and
possibly 23 also.
We were talking about that when be got an old IBM
disk archiver. I
haven't looked into it any further than that,
though.
On Wed, 17 Jan 2001, Joe wrote:
> Does anyone know what disks format the IBM
Display writer uses?
>
> Joe
>
6:44 p.m.
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?
7:53 p.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
8:36 p.m.
> 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?
Wayne, what they are discussing is the aperture in jacket that permits seeing the index and/or sector
holes.
On the Single-Sided disks that aperture is 7degrees
clockwise
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
I learn at the feet of the master. Thanks.
-W
10 p.m.
New subject: Apple/mac near portland, OR.
Here is a curious eBay ad, Local Pickup only in sounds like Portland Oregon
area. My reading of the ad is that it includes some Bell and Howell Apples.
http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=1208777810
8586
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