26 Feb
2023
26 Feb
'23
4:42 p.m.
Oi.
So after finally getting things going I started copying the Pro/380 OS
files to a bunch of 1.2mb floppies. Great. However after a bit I started
getting errors, and found that the disks were getting gouges in the
tracks. Sure enough disassembly of my 1.2mb Teac showed that debris had
become embedded in the disk head and cleaning is not possible.
Terrific. Tossing the drive, this is not the first time I have had this
problem with these disks so I am dumpstering all of the old floppies and
just bought 40 new ones in sealed boxes.
However I'm now in need of a 1.2mb floppy drive. Anyone have a good
working spare that I can beg/borrow/buy in the MD area?
Thanks!
CZ
(I really should have pitched these disks; they came from a basement
with an oil heater for 20 years and are quite honestly garbage. Only
thing worse were disks from Solarex which literally had silicon dust on
them that chewed any drive. Oh well, live and learn)
26 Feb
26 Feb
11:06 p.m.
On 2/26/23 16:42, Chris Zach via cctalk wrote:
Oi.
So after finally getting things going I started copying the Pro/380 OS
files to a bunch of 1.2mb floppies. Great. However after a bit I started
getting errors, and found that the disks were getting gouges in the
tracks. Sure enough disassembly of my 1.2mb Teac showed that debris had
become embedded in the disk head and cleaning is not possible.
Terrific. Tossing the drive, this is not the first time I have had this
problem with these disks so I am dumpstering all of the old floppies and
just bought 40 new ones in sealed boxes.
However I'm now in need of a 1.2mb floppy drive. Anyone have a good
working spare that I can beg/borrow/buy in the MD area?
I thought the Pro 300 series used RX-50 drives; i.e. 400K 96 tpi DD
media. So even with your 5.25" HD drive, you should be using DD
("360K") floppies.
You can also use a 3.5" drive running in DD mode.
FWIW,
--Chuck
27 Feb
27 Feb
6:50 a.m.
On Mon, Feb 27, 2023 at 12:06 AM Chuck Guzis via cctalk <
cctalk(a)classiccmp.org> wrote:
On 2/26/23 16:42, Chris Zach via cctalk wrote:
You should be using QD floppies, but those are rare. DD floppies from later
than
1985 though work just fine (discovered empirically while a poor college
student,
reconfirmed recently when I made all those Venix disks).
However, in a PC, to write these diskettes, you need a 1.2M drive. While
there is a couple of TEAC drives (55FR I think) that do 80-tracks at the
DD/QD
RPM and data rates, things get fussy putting them into PCs. And last time
I looked they were 5x the price of ye-olde-generic 1.2M floppy drive. As
long
as it's formatted at the right density/rpm rates, it's fine. And RX50.SYS,
if memory serves, does all that right.
Using 3.5" drives in double density mode will work, but there's a cascade
of software issues you'll have to deal with. I booted my DEC Rainbow with
these and some hacks from someone in the Jemez Mountains to do double
sided on MS-DOS (which reminds me, I have the hacks still, and they also
have a now lost-ish BIOS listing for 3.10b, so I should see if I can post
that for the few people still interested).I've never done it on a PRO
though.
I'm out in Colorado, or I'd happily give you one of my spares.
Warner
Oi.
So after finally getting things going I started copying the Pro/380 OS
files to a bunch of 1.2mb floppies. Great. However after a bit I started
getting errors, and found that the disks were getting gouges in the
tracks. Sure enough disassembly of my 1.2mb Teac showed that debris had
become embedded in the disk head and cleaning is not possible.
Terrific. Tossing the drive, this is not the first time I have had this
problem with these disks so I am dumpstering all of the old floppies and
just bought 40 new ones in sealed boxes.
However I'm now in need of a 1.2mb floppy drive. Anyone have a good
working spare that I can beg/borrow/buy in the MD area?
I thought the Pro 300 series used RX-50 drives; i.e. 400K 96 tpi DD
media. So even with your 5.25" HD drive, you should be using DD
("360K") floppies.
8:30 a.m.
On 2/27/23 06:50, Warner Losh wrote:
You should be using QD floppies, but those are rare.
DD floppies from
later than
1985 though work just fine (discovered empirically while a poor college
student,
reconfirmed recently when I made all those Venix disks).
Speaking from experience and consultations during the 1970s with
engineers from Dysan (we were using 100 tpi drives), the only difference
between QD and DD floppies is QA step--QD ones are usually verified at
96 or 100 tpi, the DD ones at 48 tpi. The brown goo spread on the
doughnut is exactly the same.
If one purchased factory-formatted diskettes for a specific platform, of
course the formatting would be different depending on the platform.
Similarly SS and DS diskettes are identical; early on, ones with
verification errors on one side were "flipped" accordingly and sold as
SS. As techniques improved, the only difference became the label.
FWIW,
Chuck
9:30 a.m.
On Mon, Feb 27, 2023 at 9:30 AM Chuck Guzis <cclist(a)sydex.com> wrote:
On 2/27/23 06:50, Warner Losh wrote:
Prior to about 1984 or 85, the failure rate for DD floppies for me was
high enough that I splurged for the QD. After 84 or 85, I never had any
problems
using DD media. I suspect that yields must have gotten better, but maybe I
just had bad luck prior to going to college...
You should be using QD floppies, but those are
rare. DD floppies from
later than
1985 though work just fine (discovered empirically while a poor college
student,
reconfirmed recently when I made all those Venix disks).
Speaking from experience and consultations during the 1970s with
engineers from Dysan (we were using 100 tpi drives), the only difference
between QD and DD floppies is QA step--QD ones are usually verified at
96 or 100 tpi, the DD ones at 48 tpi. The brown goo spread on the
doughnut is exactly the same.
If one purchased factory-formatted diskettes for a
specific platform, of
course the formatting would be different depending on the platform.
True. For the Rainbow I was always reformatting because nobody sold
pre-formatted Rainbow disks at a price that was sane.
Similarly SS and DS diskettes are identical; early on,
ones with
verification errors on one side were "flipped" accordingly and sold as
SS. As techniques improved, the only difference became the label.
I believe that..
Warner
9:54 a.m.
On 2/27/23 09:30, Warner Losh wrote:
Prior to about 1984 or 85, the failure rate for DD
floppies for me was
high enough that I splurged for the QD. After 84 or 85, I never had any
problems
using DD media. I suspect that yields must have gotten better, but maybe I
just had bad luck prior to going to college...
There was a lot of junk in the floppy arena in the early days. The
brands that vanished were numerous. Brown, Elephant...all terrible.
If I look at my 5.25" archives, most early survivors are 3M, Dysan or
Verbatim. A few Xidex. All of the off-brands have eventually failed
and been weeded out. Wabash was legendary in its awfulness in the 5.25"
area.
Of course, if you're going to use DD floppies in an RX50 drive, you'll
need to purchase some stick-on arrows...
--Chuck
11:05 a.m.
On 2/27/2023 12:54 PM, Chuck Guzis via cctalk wrote:
On 2/27/23 09:30, Warner Losh wrote:
That's funny. I used lots of Elephant on my TRS-80's and never had a
problem.
Still have them and I can still read and write them without any problems.
The only funny stuff I ran into was with 8" disks and the Terak. We
were having
problems and talked to Terak about it and their solution was that we
should be
buying Terak Brand Disks. Yeah, right, like they ever actually made
disks....
bill
Prior to about 1984 or 85, the failure rate for
DD floppies for me was
high enough that I splurged for the QD. After 84 or 85, I never had any
problems
using DD media. I suspect that yields must have gotten better, but maybe I
just had bad luck prior to going to college...
There was a lot of junk in the
floppy arena in the early days. The
brands that vanished were numerous. Brown, Elephant...all terrible. 
9:55 a.m.
On Feb 27, 2023, at 9:50 AM, Warner Losh via cctalk
<cctalk(a)classiccmp.org> wrote:
On Mon, Feb 27, 2023 at 12:06 AM Chuck Guzis via cctalk <
cctalk(a)classiccmp.org> wrote:
> ...
> I thought the Pro 300 series used RX-50 drives; i.e. 400K 96 tpi DD
> media. So even with your 5.25" HD drive, you should be using DD
> ("360K") floppies.
Yes, the Pro uses RX50 drives.
You should be using QD floppies, but those are rare.
DD floppies from later
than
1985 though work just fine (discovered empirically while a poor college
student,
reconfirmed recently when I made all those Venix disks).
However, in a PC, to write these diskettes, you need a 1.2M drive. While
there is a couple of TEAC drives (55FR I think) that do 80-tracks at the
DD/QD
RPM and data rates, things get fussy putting them into PCs. And last time
I looked they were 5x the price of ye-olde-generic 1.2M floppy drive. As
long
as it's formatted at the right density/rpm rates, it's fine. And RX50.SYS,
if memory serves, does all that right.
I don't understand that. I have a plain old Gateway PC with a twin floppy drive (3.5
and 5.25 pair). It defaults to PC format 9 sectors per track, of course. But it's
quite happy to be told to do 10 sectors per track, reading or writing. I first did so
using DOS with INT13 I/O, then in Linux with a fdparm operation, and finally in C or
Python by issuing an appropriate FDSETPRM ioctl. Works great.
You can find the machinery in my "flx" utility (for operating on RSTS file
systems); it handles both container files and actual RX50 format floppies. This is how I
write disks for my Pro to consume.
paul
10:10 a.m.
On Mon, 27 Feb 2023, Warner Losh wrote:
You should be using QD floppies, but those are rare.
DD floppies from
later than 1985 though work just fine (discovered empirically while a
Are they? I guess that I have at least as many QD floppies as DD, if not
even more. :-)
However, in a PC, to write these diskettes, you need a
1.2M drive. While
there is a couple of TEAC drives (55FR I think) that do 80-tracks at the
DD/QD RPM and data rates, things get fussy putting them into PCs. And
last time I looked they were 5x the price of ye-olde-generic 1.2M floppy
drive. As long as it's formatted at the right density/rpm rates, it's
fine. And RX50.SYS, if memory serves, does all that right.
When giving an advise, it should be as correct as possible ;-))
So no, you don't need a "1.2M drive" (i.e. high density). You just need a
96 tpi drive. And the drive is totally (well, almost) ignorant of the data
rate. It is just spinning the media at a specific velocity (300 or 360
rpm). When using a 300 rpm drive, you need a 250 kHz data rate for DD (QD
is the same, it's just a marketing name for 96 tpi DD). With 360 rpm you
need a 300 kHz data rate. It only gets a little bit complicated if you
jumper a high-density drive for dual-speed mode (300 rpm if DD, 360 rpm if
HD).
Using 3.5" drives in double density mode will
work, but there's a cascade
of software issues you'll have to deal with. I booted my DEC Rainbow with
It would be the same for a normal 5¼" double sided drive. IIRC the trick
is to combine the RX50 specific drive selects to one drive select and one
head select. The software should not know anything about this. Drive 0
would be side 0, and drive 1 side 1.
Christian
10:21 a.m.
As already said here most of the better DSDD diskettes could handle 48
or 96 TPI.
The biggest problem I remember from that era (on 6809 Systems in the
early '80s and early PC's) is intermixing 48 and 96 tpi drives and
reading/writing both drives.
Since the tracks are half as wide on the 96 TPI drive, if you format a
disk on a 48 TPI drive and then write to it on a 96 PTI drive and then
try to read it back on a 48 TPI drive, the reads may fail because the 96
TPI drive only wrote half of the track as seen by the 48 TPI drive.
When reading data on a 48PTI drive, the drive would see half the new
data and half the old data.
Also the 96 TPI drive needed to be double stepped to read a 48 TPI
formatted diskette.
On 2/27/2023 12:10 PM, Christian Corti via cctalk wrote:
On Mon, 27 Feb 2023, Warner Losh wrote:
You should be using QD floppies, but those are
rare. DD floppies from
later than 1985 though work just fine (discovered empirically while a
Are they? I guess that I have at least as many QD floppies as DD, if
not even more. :-)
However, in a PC, to write these diskettes, you
need a 1.2M drive.
While there is a couple of TEAC drives (55FR I think) that do
80-tracks at the DD/QD RPM and data rates, things get fussy putting
them into PCs. And last time I looked they were 5x the price of
ye-olde-generic 1.2M floppy drive. As long as it's formatted at the
right density/rpm rates, it's fine. And RX50.SYS, if memory serves,
does all that right.
When giving an advise, it should be as correct as possible ;-))
So no, you don't need a "1.2M drive" (i.e. high density). You just
need a 96 tpi drive. And the drive is totally (well, almost) ignorant
of the data rate. It is just spinning the media at a specific velocity
(300 or 360 rpm). When using a 300 rpm drive, you need a 250 kHz data
rate for DD (QD is the same, it's just a marketing name for 96 tpi
DD). With 360 rpm you need a 300 kHz data rate. It only gets a little
bit complicated if you jumper a high-density drive for dual-speed mode
(300 rpm if DD, 360 rpm if HD).
Using 3.5" drives in double density mode
will work, but there's a
cascade
of software issues you'll have to deal with. I booted my DEC Rainbow
with
It would be the same for a normal 5¼" double sided drive. IIRC the
trick is to combine the RX50 specific drive selects to one drive
select and one head select. The software should not know anything
about this. Drive 0 would be side 0, and drive 1 side 1.
Christian 
12:55 p.m.
On Feb 27, 2023, at 10:21 AM, Mike Katz via cctalk
<cctalk(a)classiccmp.org> wrote:
the drive would see half the new data and half the old data.
I think that explaining it this way can easily lead to an incorrect inference on the part
of an arbitrary hypothetical neophyte that what is going on in the drive in such a case is
that the head can equally well read either the old data or the new data but the controller
can’t distinguish which is which, or might return old data, or might return new data, or
might indiscriminately return some old data and some new.
What the drive reads in such a case is noise, because the wider head picks up a
superposition of the old (wide) 48tpi track data AND the new (narrow) 96tpi track data,
simultaneously.
ok
bear.
1:22 p.m.
Actually it's not the controller, it is the fact that the head gap on
the 48 tpi drive is twice as wide as on the 96TPI drive.
So the actual head sees the magnetic fluxes from two different tracks,
This looks like noise to the data separator on the controller.
The way around this was to magnetically erase a disk and format it and
write it on a double stepped on a 96tpi drive and only read it in a 48
tpi drive.
This is what we had to do when I wrote the floppy formatter for Gimix
6800 and 6809 Flex and OS/9. The floppy driver also had an option to
double step the drive for normal Flex operation.
On 2/27/2023 2:55 PM, r.stricklin via cctalk wrote:
On Feb 27,
2023, at 10:21 AM, Mike Katz via cctalk <cctalk(a)classiccmp.org> wrote:
the drive would see half the new data and half the old data.
I think that
explaining it this way can easily lead to an incorrect inference on the part of an
arbitrary hypothetical neophyte that what is going on in the drive in such a case is that
the head can equally well read either the old data or the new data but the controller
can’t distinguish which is which, or might return old data, or might return new data, or
might indiscriminately return some old data and some new.
What the drive reads in such a case is noise, because the wider head picks up a
superposition of the old (wide) 48tpi track data AND the new (narrow) 96tpi track data,
simultaneously.
ok
bear.
1:36 p.m.
On 2/27/23 12:55, r.stricklin via cctalk wrote:
Double-stepped disks written at 96 tpi are perfectly readable on a 48
tpi drive if the disks are bulk-erased first. I've done this using a
videotape eraser and later, a DC eraser made up of two ring magnets from
an old magnetron, spaced perhaps 3-4 mm apart with like poles facing
each other. Just pass the disk around the gap. Works a treat.
--Chuck
On Feb 27, 2023, at 10:21 AM, Mike Katz via
cctalk <cctalk(a)classiccmp.org> wrote:
the drive would see half the new data and half the old data.
I think that explaining it this way can easily lead to an incorrect inference on the part
of an arbitrary hypothetical neophyte that what is going on in the drive in such a case is
that the head can equally well read either the old data or the new data but the controller
can’t distinguish which is which, or might return old data, or might return new data, or
might indiscriminately return some old data and some new.
What the drive reads in such a case is noise, because the wider head picks up a
superposition of the old (wide) 48tpi track data AND the new (narrow) 96tpi track data,
simultaneously. 
2:14 p.m.
For my students, I used analogies and visual aids.
1/48, 1/96 is a little hard for some to visualize.
"48 tracks per inch, is about half a millimeter spacing, with the actual
data being aabout a third of a millimeter wide.
96 tracks per inch is about a quarter of a millimeter spacing, with the
cata being about a sixth of a millimeter wide"
"If you make stripes with a 2 inch wide paint brush, . . .
you can also make stripes with the same spacing, with aa 1 inch wide paint
brush, . . .
BUT, with a single stroke, can you paint over a 2 inch stripe with a 1
inch brush?
No, you'd have to clean all of the old paint off first, or start with a
virgin canvas."
"car tires make two tracks. Motorcycles could make tracks the same
spacing. But, motorcycles won't obliterate the car tire tracks."
I took a wide piece of colored chalk and made a series of stripes. I held
up a piece of cardboard (file folder) with a slit in it, and looked at one
stripe.
With a narrower piece of a different color chalk, I made a series of half
width stripes, half as far apart. I used a corresponding piece of
cardboard with a narrower slit.
I made narrow sripes at the wide spacing. I used the narrow slit
cardboard, and then the wider slit cardboard, "Maybe a little weaak, but
it should do."
Then I made narrow stripes down the middle of the end of the wide stripes.
I used the narrow slit cardboard. "Looks fine."
Then I used the wide slit cardboard. "What is this mess??"
Then, I made the students describe how to make a 48tpi disk with a 96tpi
drive.
--
Grumpy Ol' Fred cisin(a)xenosoft.com
3:29 p.m.
On 2/27/23 14:14, Fred Cisin via cctalk wrote:
Then, I made the students describe how to make a 48tpi
disk with a 96tpi
drive.
One thing that folks need to bear in mind is that it's the change of
direction of magnetization that induces a signal in a drive head. So a
DC or AC erase on the "straddling" portions of a track will work equally
as well.
--Chuck
3:50 p.m.
> Then, I made the students describe how to make a
48tpi disk with a 96tpi
> drive.
Whether to count their answers as acceptable or not was mostly just the
understanding of need for "bulk erase"/"virgin disk"
On Mon, 27 Feb 2023, Chuck Guzis via cctalk wrote:
One thing that folks need to bear in mind is that
it's the change of
direction of magnetization that induces a signal in a drive head. So a
DC or AC erase on the "straddling" portions of a track will work equally
as well.
There is some erasing done by the heads to clear some of the area around
the track. BUT, that erase of a 96tpi head is not wide enough to remove
all traces of a previous 48tpi recording.
I wondered why they didn't incorporate TWO sets of erase heads in 1.2M
drives, so that it could "clear the margins" enough for 96tpi OR 48tpi
re-writing.
Could you explain [in dumbed down form], the differences between "tunnel
erase" and "straddle erase"? Is it solely that the erase head(s) are
behind, VS alongside the R/W head?
I looked at
http://www.bitsavers.org/pdf/cdc/discs/floppy/75897469_5inchFDD_Fmt_Jan80.p…
but I don't understand all of it.
--
Grumpy Ol' Fred cisin(a)xenosoft.com
4:12 p.m.
On 2/27/23 15:50, Fred Cisin via cctalk wrote:
Could you explain [in dumbed down form], the
differences between "tunnel
erase" and "straddle erase"? Is it solely that the erase head(s) are
behind, VS alongside the R/W head?
How about ChatGPT's explanation? (Is this a first for CCTalk?):
When recording signals on magnetic media, erasing the previous data from
the media is an important step in preparing it for new data. Tunnel
erase and straddle erase are two different methods used for this
purpose, and they differ in how they erase the previous data from the media.
Tunnel erase is a method of erasing the previous data by applying a
magnetic field perpendicular to the direction of the recording tracks.
This magnetic field is strong enough to create a "tunneling effect" that
causes the magnetic particles on the media to lose their magnetic
orientation, effectively erasing the previous data. This method is
called "tunnel erase" because the magnetic field creates a tunnel
through which the magnetic particles lose their orientation.
On the other hand, straddle erase is a method of erasing the previous
data by applying a magnetic field that is parallel to the direction of
the recording tracks. The magnetic field is applied by two or more
magnetic heads placed on either side of the recording tracks, creating a
"straddle" configuration. The magnetic field from the heads is strong
enough to erase the previous data by realigning the magnetic particles
on the media in a uniform direction.
In summary, tunnel erase and straddle erase are two different methods of
erasing the previous data from magnetic media. Tunnel erase uses a
perpendicular magnetic field to erase the previous data, while straddle
erase uses a parallel magnetic field created by multiple magnetic heads.
-Chuck
10:49 a.m.
On Mon, Feb 27, 2023 at 11:10 AM Christian Corti via cctalk <
cctalk(a)classiccmp.org> wrote:
Correct. You don't need a 1.2M drive. That's true. However, getting the
96tpi QD
300prm 250kHz drives are a lot harder these days than finding an old 1.2M
drive.
I recently looked for the TEAC 55FR drives that I used back in the day, and
could
not find them at all. Found plenty of other TEAC 55xx drives that were all
either
'360k' or '1.2M' drives. So it was more of a practical bit of advice,
than
an absolute
requirement...
While several of the newer drives do allow dual speed operations, the floppy
cables for the RX-50 drive don't have the necessary signals to switch them.
IDrives
used a transistor to switch the signals properly for these drives. I opted
to use
drives that didn't need this signal. For 3.5" drives, there weren't any
hacks
needed because that signal was ignored by most of the drives.
I rarely used them on a PC back in the day, so I'll defer to others on that.
The trick is just to use two double sided drives, the side select stuff is
there,
and you just need to jumper the drives to be ID0 and ID1 to get your A & B
drives. You have to use for this, though, drives that can do 300rpm at
250kHz
because that's what (at least the Rainbow) RX-50 controller puts out. I ran
this way for many years, though the software changes to MS-DOS were a bit
flakey for me, and I never found ones for CP/M.
I only got the 3.5" floppy drives that were the lower density to work,
since those
were also 300rpm/250kHz. I never got the high density ones to work since at
least the ones I looked at didn't have the density signal, nor density
jumpers.
Wrote a 'driver' for it called IMPDRIVE back in the day. Some 5.25" drives
would
work with it (like the TEAC 55FRs), but many would not. And my old FRs are
toast and I've not been able to find good replacements to try this again...
Warner
On Mon, 27 Feb 2023, Warner Losh wrote:
I'd guess at least as many HD floppies, likely way more. QD was a pretty odd
duck, and any
You should be using QD floppies, but those are
rare. DD floppies from
later than 1985 though work just fine (discovered empirically while a
Are they? I guess that I have at least as many QD floppies as DD, if not
even more. :-)
However, in a
PC, to write these diskettes, you need a 1.2M drive. While
there is a couple of TEAC drives (55FR I think) that do 80-tracks at the
DD/QD RPM and data rates, things get fussy putting them into PCs. And
last time I looked they were 5x the price of ye-olde-generic 1.2M floppy
drive. As long as it's formatted at the right density/rpm rates, it's
fine. And RX50.SYS, if memory serves, does all that right.
When giving an advise, it should be as correct as possible ;-))
So no, you don't need a "1.2M drive" (i.e. high density). You just need a
96 tpi drive. And the drive is totally (well, almost) ignorant of the data
rate. It is just spinning the media at a specific velocity (300 or 360
rpm). When using a 300 rpm drive, you need a 250 kHz data rate for DD (QD
is the same, it's just a marketing name for 96 tpi DD). With 360 rpm you
need a 300 kHz data rate. It only gets a little bit complicated if you
jumper a high-density drive for dual-speed mode (300 rpm if DD, 360 rpm if
HD).
Using
3.5" drives in double density mode will work, but there's a cascade
of software issues you'll have to deal with. I booted my DEC Rainbow with
It would be the same for a normal 5¼" double sided drive. IIRC the trick
is to combine the RX50 specific drive selects to one drive select and one
head select. The software should not know anything about this. Drive 0
would be side 0, and drive 1 side 1.
3:53 p.m.
It is also worth noting, that although not all "360K" diskettes are up to
the task, they will still be much closer than "HD"/"1.2M" diskettes!
"360K" diskettes are 300 Oersted
"Quad density" diskettes are also 300 Oersted. The only difference is
that "QD" diskettes are tested for 96tpi, whereas "360K" diskettes are
tested at 48tpi. They are made of identical materials. However, if the
production quality control is marginal/poor, then you could have
some/many? that test OK at 48tpi, but are too flawed for 96tpi use. If
they are really good quality, then the 48tpi ones should work just fine.
OTOH, "HD"/"1.2M" diskettes are 600 oersted. Use of those for DD
300RPm/250Kbps / 360RPM/300kbps recording, whether at 48tpi, or 96tpi,
will result in data retention longevity that is lower than it should be.
Testing Roytype "HD" diskettes on TRS80 model 1 (SD/FM), gave data life of
MINUTES, whereas "360K" diskettes tend to last years
However, 3.5" "720K" diskettes are about 600 Oersted, and "1.4M"
are about
720-750 Oersted. That is close enough that using the wrong media is
something that people often get away with.
I do not currently own a coercivity meter, so I can't check compliance
with the specs.
45 years ago, Verbatim made some very crappy diskettes. To recover from
their bad reputation, they came out with "Datalife" diskettes, which were
acceptable quality.
Dysan seems to have always been good. However, they "bet the company" on
3.25" disk form factor, and lost.
--
Grumpy Ol' Fred cisin(a)xenosoft.com
28 Mar
28 Mar
2:12 p.m.
Hi Chris,
I had a bunch of 1.2Mb 5-1/4" drives that, unfortunately, may have been discarded
over the past year. I mainly hung on to all of the 360K FDDs that I came across, which are
more difficult to find. I know that I still have some NOS 1.2Mb units (never been powered
up, but also not taken out of their original plastic bags either.) I bought these new from
a local computer store (still in business, but now doing mostly consulting work,
unfortunately) many years ago (early 2000's) to support some clients that used them. I
have (or had) used, tested 1.2Mb drives also.
Alas, I am near Buffalo, NY and not too close to MD, but am willing to pack and ship. I
see from the replies that I have read that nobody has offered drives. If you are still
interested, I can look up the models of the units that I still have and from which I can
part.
Best,
-John
-----Original Message-----
From: Chris Zach via cctalk <cctalk(a)classiccmp.org>
Sent: Sunday, 26 February, 2023 19:42
To: CCTalk mailing list <cctalk(a)classiccmp.org>
Cc: Chris Zach <cz(a)beaker.crystel.com>
Subject: [cctalk] Need a 1.2mb 5.25 floppy
Oi.
So after finally getting things going I started copying the Pro/380 OS files to a bunch of
1.2mb floppies. Great. However after a bit I started getting errors, and found that the
disks were getting gouges in the tracks. Sure enough disassembly of my 1.2mb Teac showed
that debris had become embedded in the disk head and cleaning is not possible.
Terrific. Tossing the drive, this is not the first time I have had this problem with these
disks so I am dumpstering all of the old floppies and just bought 40 new ones in sealed
boxes.
However I'm now in need of a 1.2mb floppy drive. Anyone have a good working spare that
I can beg/borrow/buy in the MD area?
Thanks!
CZ
(I really should have pitched these disks; they came from a basement with an oil heater
for 20 years and are quite honestly garbage. Only thing worse were disks from Solarex
which literally had silicon dust on them that chewed any drive. Oh well, live and learn)
29 Mar
29 Mar
4:47 a.m.
We have a case or two of 1.2m diskette, we sell by the box or individually
at Kennett Classic (kennettclassic.com) not sure how far you are from the
MD/PA/DE border
Bill
On Wed, Mar 29, 2023, 7:32 AM John Maxwell via cctalk <cctalk(a)classiccmp.org>
wrote:
Hi Chris,
I had a bunch of 1.2Mb 5-1/4" drives that, unfortunately, may have been
discarded over the past year. I mainly hung on to all of the 360K FDDs that
I came across, which are more difficult to find. I know that I still have
some NOS 1.2Mb units (never been powered up, but also not taken out of
their original plastic bags either.) I bought these new from a local
computer store (still in business, but now doing mostly consulting work,
unfortunately) many years ago (early 2000's) to support some clients that
used them. I have (or had) used, tested 1.2Mb drives also.
Alas, I am near Buffalo, NY and not too close to MD, but am willing to
pack and ship. I see from the replies that I have read that nobody has
offered drives. If you are still interested, I can look up the models of
the units that I still have and from which I can part.
Best,
-John
-----Original Message-----
From: Chris Zach via cctalk <cctalk(a)classiccmp.org>
Sent: Sunday, 26 February, 2023 19:42
To: CCTalk mailing list <cctalk(a)classiccmp.org>
Cc: Chris Zach <cz(a)beaker.crystel.com>
Subject: [cctalk] Need a 1.2mb 5.25 floppy
Oi.
So after finally getting things going I started copying the Pro/380 OS
files to a bunch of 1.2mb floppies. Great. However after a bit I started
getting errors, and found that the disks were getting gouges in the tracks.
Sure enough disassembly of my 1.2mb Teac showed that debris had become
embedded in the disk head and cleaning is not possible.
Terrific. Tossing the drive, this is not the first time I have had this
problem with these disks so I am dumpstering all of the old floppies and
just bought 40 new ones in sealed boxes.
However I'm now in need of a 1.2mb floppy drive. Anyone have a good
working spare that I can beg/borrow/buy in the MD area?
Thanks!
CZ
(I really should have pitched these disks; they came from a basement with
an oil heater for 20 years and are quite honestly garbage. Only thing worse
were disks from Solarex which literally had silicon dust on them that
chewed any drive. Oh well, live and learn)
6:44 a.m.
Hi John!
Thanks for the reply. I've been a bit busy but yes I would love to
replace this drive and be able to read these 400k RX50 floppies.
If you have a pair of the Teac type drives that will work in a PC-AT
type system I'd be happy to pay for shipping and whatnot via Paypal.
Given the number of Pro/350 install floppies I'd like to image I might
want to have a spare.
Just drop me an amount off-list, and thank you for the help!
Chris
On 3/28/2023 5:12 PM, John Maxwell via cctalk wrote:
Hi Chris,
I had a bunch of 1.2Mb 5-1/4" drives that, unfortunately, may have been
discarded over the past year. I mainly hung on to all of the 360K FDDs that I came across,
which are more difficult to find. I know that I still have some NOS 1.2Mb units (never
been powered up, but also not taken out of their original plastic bags either.) I bought
these new from a local computer store (still in business, but now doing mostly consulting
work, unfortunately) many years ago (early 2000's) to support some clients that used
them. I have (or had) used, tested 1.2Mb drives also.
Alas, I am near Buffalo, NY and not too close to MD, but am willing to pack and ship.
I see from the replies that I have read that nobody has offered drives. If you are still
interested, I can look up the models of the units that I still have and from which I can
part.
Best,
-John
-----Original Message-----
From: Chris Zach via cctalk <cctalk(a)classiccmp.org>
Sent: Sunday, 26 February, 2023 19:42
To: CCTalk mailing list <cctalk(a)classiccmp.org>
Cc: Chris Zach <cz(a)beaker.crystel.com>
Subject: [cctalk] Need a 1.2mb 5.25 floppy
Oi.
So after finally getting things going I started copying the Pro/380 OS files to a bunch
of 1.2mb floppies. Great. However after a bit I started getting errors, and found that the
disks were getting gouges in the tracks. Sure enough disassembly of my 1.2mb Teac showed
that debris had become embedded in the disk head and cleaning is not possible.
Terrific. Tossing the drive, this is not the first time I have had this problem with
these disks so I am dumpstering all of the old floppies and just bought 40 new ones in
sealed boxes.
However I'm now in need of a 1.2mb floppy drive. Anyone have a good working spare
that I can beg/borrow/buy in the MD area?
Thanks!
CZ
(I really should have pitched these disks; they came from a basement with an oil heater
for 20 years and are quite honestly garbage. Only thing worse were disks from Solarex
which literally had silicon dust on them that chewed any drive. Oh well, live and learn)
633
days inactive
663
days old
21 comments
11 participants
participants (11)
-
Bill Degnan -
Bill Gunshannon -
Chris Zach -
Christian Corti -
Chuck Guzis -
Fred Cisin -
John Maxwell -
Mike Katz -
Paul Koning -
r.stricklin -
Warner Losh