2 Sep
2022
2 Sep
'22
1:51 p.m.
All the discussion around 8" disks reminded me about a question I've not
been able to find an answer to.
I've got a Qumetrak 842 drive that I use for imaging 8" disks with either
ImageDisk or AppleSauce. When I first tried it out with AS, the listed
RPM was > 7K. It turns out that the disk I was working with was a NOS
Dysan that had both the single and double-sided index windows punched in
the jacket. The 842 has both of those index sensors, so both were being
triggered one after the other. The solution was to cover one of the index
windows on the disk.
The question I have is how did a contemporary system deal with the
combination of a disk with both index windows and a drive with both index
sensors?
tnx!
g.
--
Proud owner of F-15C 80-0007
http://www.f15sim.com - The only one of its kind.
http://www.diy-cockpits.org/coll - Go Collimated or Go Home.
Some people collect things for a hobby. Geeks collect hobbies.
ScarletDME - The red hot Data Management Environment
A Multi-Value database for the masses, not the classes.
http://scarlet.deltasoft.com - Get it _today_!
2 Sep
2 Sep
3:35 p.m.
On Fri, 2 Sep 2022, geneb via cctalk wrote:
All the discussion around 8" disks reminded me
about a question I've not been
able to find an answer to.
I've got a Qumetrak 842 drive that I use for imaging 8" disks with either
ImageDisk or AppleSauce. When I first tried it out with AS, the listed RPM
was > 7K.
well, 720, not 7K
It turns out that the disk I was working with was a
NOS Dysan that
had both the single and double-sided index windows punched in the jacket.
The 842 has both of those index sensors, so both were being triggered one
after the other. The solution was to cover one of the index windows on the
disk.
The question I have is how did a contemporary system deal with the
combination of a disk with both index windows and a drive with both index
sensors?
THAT is why I asked:
> > How do they handle the issue of how the
drive knows whether it is
> > SS, DS, or SS flippy? Or is it assumed that that problem is for the
> > host FDC?
> > (some DS drives had both SS and DS index sensors, so that they could
> > read SS in the DS drive, and such a drive is going to see TWO index
> > pulses with this disk!)
and Chuck replied:
> I think I was using a Qume 842 to read the disk
and it turned out to
> be double-sided, so there was no problem reading it. The disk itself
> probably arrived here 30 years ago, so my memory may be faulty.
> This isn't the first floppy I've seen with both SS and DS holes,
> however. I recall that using a write-enable sticky over the
> appropriate index aperture resolved the problem of side-edness.
Obviously, it can be left to the user to mask off any extraneous index
hole(s). And a more sophisticated engineering solution was not provided.
Junpers to separately disable each index sensor with an open case, or
brought out to accessible switches would be a "RIGHT" way to handle it.
For reading and writing (not formatting) with a WD controller, you might
not even notice a problem.
But, with a 765 type controller, the long "flash blindness" (which will
happen twice per revolution), means some sectors are likely to be
inaccessible.
Once you know whether the disk is SS or DS, then you should mask the
extraneous hole.
If you are FORMATTING, then YOU know whether you are SS or DS, and know
which hole to mask.
I used right protect tabs, but made sure their adhesive was in good shape!
I was also glad that they changed the write protect/enable notch location.
My first used 8" drive came with a handful of write enable tabs in the
back of the drive. Obviously, Bill Gates' "Computer Bowl" team were
people who had had OTHER people open the case and fish out the tabs that
had fallen off, or never had to re-enable write on a disk.
What never?
no never.
What never?
Well, hardly ever. (cf. "H.M.S. Pinafore", Gilbert & Sullivan)
The 5.25" location was more prone to friction knocking them off, but
easier to get to. And, I had a folded business card handy that I could
wrap over the notch and carefully slide in with the diskette for a
temporary protect. (and drive(s) dedicated to disk analysis jumpered to
disable write enable) SA455 had a simple jumper to reverse write
enable/protect sensing (software distribution went out on no-notch 5.25"
disks)
--
Grumpy Ol' Fred cisin(a)xenosoft.com
4:05 p.m.
On Fri, 2 Sep 2022, Fred Cisin via cctalk wrote:
On Fri, 2 Sep 2022, geneb via cctalk wrote:
No, it was actually some absurdly huge number. It has something to do
with how the AS hardware & software was working out the RPM of the drive.
g.
--
Proud owner of F-15C 80-0007
http://www.f15sim.com - The only one of its kind.
http://www.diy-cockpits.org/coll - Go Collimated or Go Home.
Some people collect things for a hobby. Geeks collect hobbies.
ScarletDME - The red hot Data Management Environment
A Multi-Value database for the masses, not the classes.
http://scarlet.deltasoft.com - Get it _today_!
All the discussion around 8" disks reminded
me about a question I've not
been able to find an answer to.
I've got a Qumetrak 842 drive that I use for imaging 8" disks with either
ImageDisk or AppleSauce. When I first tried it out with AS, the listed RPM
was > 7K.
well, 720, not 7K
4:15 p.m.
On 09/02/2022 11:05 AM CDT geneb via cctalk
<cctalk(a)classiccmp.org> wrote:
On Fri, 2 Sep 2022, Fred Cisin via cctalk wrote:
My "guess" would be measuring/counting the time between index pulses and since
it got to measure it twice in one revolution, the time between them was, say, 1/16th or so
the normal time.
Will
You don't understand anything until you learn it more than one way.
Marvin Minsky
well, 720, not 7K
No, it was actually some
absurdly huge number. It has something to do
with how the AS hardware & software was working out the RPM of the drive.
g. 
4:09 p.m.
The discussion about 8" write enable tabs reminds me of a box of Imation
disks that I have here. I was asked to make a few copies for a customer
and was absolutely stymied when the target disks kept showing up as
write-protected.
It turned out that the Imation-provided tabs are made of a translucent
red-colored plastic with the appropriate sticky coating. Evidently, the
tabs aren't sufficiently opaque for the write-enable optical sensors on
my Siemens drives.
Replacing the tabs with ordinary foil tabs solved the problem.
--Chuck
22 Sep
22 Sep
5:50 a.m.
On Fri, Sep 2, 2022, 07:51 geneb via cctalk <cctalk(a)classiccmp.org> wrote:
The question I have is how did a contemporary system
deal with the
combination of a disk with both index windows and a drive with both index
sensors?
They didn't deal with it at all. It didn't work. No normal 8-inch floppy
disks have both index holes in the jacket. If you convert a disk from SS to
DS, or vice versa, by punching the other index hole in the jacket, you have
to cover the original, unless you're going to use it in a drive that has
only one index sensor (typically an SS drive).
7:04 p.m.
On Wed, 21 Sep 2022, Eric Smith via cctalk wrote:
On Fri, Sep 2, 2022, 07:51 geneb via cctalk
<cctalk(a)classiccmp.org> wrote:
I've got at least three boxes of NOS Dysan disks with both of those index
holes present, so they certainly were made commercially.
g.
--
Proud owner of F-15C 80-0007
http://www.f15sim.com - The only one of its kind.
http://www.diy-cockpits.org/coll - Go Collimated or Go Home.
Some people collect things for a hobby. Geeks collect hobbies.
ScarletDME - The red hot Data Management Environment
A Multi-Value database for the masses, not the classes.
http://scarlet.deltasoft.com - Get it _today_!
The question I have is how did a contemporary
system deal with the
combination of a disk with both index windows and a drive with both index
sensors?
They didn't deal with it at all. It didn't work. No normal 8-inch floppy
disks have both index holes in the jacket. If you convert a disk from SS to
DS, or vice versa, by punching the other index hole in the jacket, you have
to cover the original, unless you're going to use it in a drive that has
only one index sensor (typically an SS drive). 
7:36 p.m.
Looking at the circuit of the Qume drive, it is certainly not designed to work with disks
with both holes, I can only imagine that drives only expected disks to be one or the other
when it was designed, but it could easily be modified with a three position On-Off-On
switch to disable either index sensor, or to have both working as usual...
Robin
-----Original Message-----
From: Chuck Guzis via cctalk <cctalk(a)classiccmp.org>
Sent: 22 September 2022 20:23
To: cctalk(a)classiccmp.org
Cc: Chuck Guzis <cclist(a)sydex.com>
Subject: [cctalk] Re: 8" disk question!
On 9/22/22 12:04, geneb via cctalk wrote:
only one index sensor (typically an SS drive).
I've got at least three boxes of NOS Dysan disks with both of those
index holes present, so they certainly were made commercially.
Yup. I've got similar NOS ones also.
--Chuck
8:31 p.m.
On Wed, 21 Sep 2022, Eric Smith via cctalk wrote:
>> They didn't deal with it at all. It
didn't work. No normal 8-inch
>> floppy disks have both index holes in the jacket. If you convert a
>> disk from SS to DS, or vice versa, by punching the other index hole in
>> the jacket, you have to cover the original, unless you're going to use
>> it in a drive that has only one index sensor (typically an SS drive).
On 9/22/22 12:04, geneb via cctalk wrote:
> I've got at least three boxes of NOS Dysan
disks with both of those
> index holes present, so they certainly were made commercially.
On Thu, 22 Sep 2022, Chuck Guzis via cctalk wrote:
Yup. I've got similar NOS ones also.
Since those are not "normal", or at least uncommon, please send one such
disk to Eric for his collection of odd stuff.
It would have made sense for a drive with both sensors to have jumpers,
that could, if needed often, be wired to a switch.
When I repunched 8" disks, I put a write-enable tab over the old hole.
--
Grumpy Ol' Fred cisin(a)xenosoft.com
8:37 p.m.
That's how Cromemco shipped their distribution disks, with both holes and a
sticker to cover the unused hole with arrows on it to show which way was
which.
m
On Thu, Sep 22, 2022 at 4:32 PM Fred Cisin via cctalk <cctalk(a)classiccmp.org>
wrote:
On Wed, 21 Sep 2022, Eric Smith via cctalk wrote:
>> They didn't deal with it at all. It
didn't work. No normal 8-inch
>> floppy disks have both index holes in the jacket. If you convert a
>> disk from SS to DS, or vice versa, by punching the other index hole in
>> the jacket, you have to cover the original, unless you're going to use
>> it in a drive that has only one index sensor (typically an SS drive).
On 9/22/22 12:04, geneb via cctalk wrote:
> I've got at least three boxes of NOS
Dysan disks with both of those
> index holes present, so they certainly were made commercially.
On Thu, 22 Sep 2022, Chuck Guzis via cctalk wrote:
Yup. I've got similar NOS ones also.
Since those are not "normal", or at least uncommon, please send one such
disk to Eric for his collection of odd stuff.
It would have made sense for a drive with both sensors to have jumpers,
that could, if needed often, be wired to a switch.
When I repunched 8" disks, I put a write-enable tab over the old hole.
--
Grumpy Ol' Fred cisin(a)xenosoft.com
8:38 p.m.
On 9/22/22 16:31, Fred Cisin via cctalk wrote:
On Wed, 21 Sep 2022, Eric Smith via cctalk wrote:
Never having seen anything like this myself, I would be interested in
how the box is labeled!!
bill
>> They didn't deal with it at all. It
didn't work. No normal 8-inch
>> floppy disks have both index holes in the jacket. If you convert a
>> disk from SS to DS, or vice versa, by punching the other index hole
>> in the jacket, you have to cover the original, unless you're going
>> to use it in a drive that has only one index sensor (typically an SS
>> drive).
On 9/22/22 12:04, geneb via cctalk wrote:
> I've got at least three boxes of NOS
Dysan disks with both of those
> index holes present, so they certainly were made commercially.
On Thu, 22 Sep 2022, Chuck Guzis via cctalk wrote:
Yup. I've got similar NOS ones also.
Since those are not "normal", or at least uncommon, please send one such
disk to Eric for his collection of odd stuff.
It would have made sense for a drive with both sensors to have jumpers,
that could, if needed often, be wired to a switch.
When I repunched 8" disks, I put a write-enable tab over the old hole.
791
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11 comments
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