8 Sep
2006
8 Sep
'06
11:32 a.m.
These are 5 1/4" form factor floppies, but hold twice the data. I have
already
searched ebay and google, so I need other suggestions, or someone who can
part with some
I don't know if regular or "premium" 5 1/4 inch 1.2mb media can be
formatted
and used with them or not.
Thanks.
Jim
8 Sep
8 Sep
12:17 p.m.
On 9/8/2006 at 8:32 AM jim stephens wrote:
These are 5 1/4" form factor floppies, but hold
twice the data. I have
already searched ebay and google, so I need other suggestions, or someone
who can
part with some
Scarcer than hen's teeth, I'm afraid. These went with the Drivetec drives
that could be found in the Kaypro Robie.
The problem is that these use an embedded servo and blank floppies were
formatted by the factory--the user could not format his own. I've never
found more than the occasional one here and there, probably because when
purchased new, these were sold by the single unit and rather
expensive--about $5 each, 1980 prices.
The 6.4 MB ones are even scarcer.
Cheers,
Chuck
1:01 p.m.
--- Chuck Guzis <cclist at sydex.com> wrote:
On 9/8/2006 at 8:32 AM jim stephens wrote:
I've seen them used in IBM terminal controllers as
microcode floppies. The drives for said terminal
controllers are easy to find - I have many. Disks are
scarcer. I don't know if the IBM 2.4 meg disk is the
same as the ones used by the Kaypro. I also don't know
much about how the format works.
-Ian
These are 5 1/4" form factor floppies, but
hold
twice the data. I have
already searched ebay and google, so I need other
suggestions, or someone
who can
part with some
Scarcer than hen's teeth, I'm afraid. These went
with the Drivetec drives
that could be found in the Kaypro Robie.
1:37 p.m.
Mr Ian Primus wrote:
--- Chuck Guzis <cclist at sydex.com> wrote:
I am looking for the Microcode variety. I have a lot of Drivetec media,
but I am not certain that is what is needed for the 2.4mb drives.
I have not researched anything on the 2.4mb drives or formatting, any
links or info on that? I would doubt they had the Drivetec type approach,
because these floppy drives appeared before the Drivetec stuff was out.
Maybe this was just a different media, head and double the wiggles, rather
than the Drivtec approach of embedded servo, and all that rot? They were
shooting for 30mb on a floppy, IIRC and had a drive that would sort of
do that after Kodak took them over. The 6mb variety was just something
they put out to try to survive, but their drives and electronics sucked
and doomed them.
Jim
On 9/8/2006 at 8:32 AM jim stephens wrote:
I've seen them used in IBM terminal controllers as
microcode floppies. The drives for said terminal
controllers are easy to find - I have many. Disks are
scarcer. I don't know if the IBM 2.4 meg disk is the
same as the ones used by the Kaypro. I also don't know
much about how the format works.
-Ian
These are 5 1/4" form factor floppies, but
hold
twice the data. I have
already searched ebay and google, so I need other
suggestions, or someone
who can
part with some
Scarcer than hen's teeth, I'm afraid. These went
with the Drivetec drives
that could be found in the Kaypro Robie.
3:13 p.m.
On 9/8/2006 at 10:37 AM jim stephens wrote:
I have not researched anything on the 2.4mb drives or
formatting, any
links or info on that? I would doubt they had the Drivetec type approach,
because these floppy drives appeared before the Drivetec stuff was out.
So, you've got a YD-802-4 drive under all of the IBM skin, right? And
you're not using it with an IBM 3174 controller?
What other piece of equipment used these?
Cheers,
Chuck
4:54 p.m.
Chuck Guzis wrote:
<>On 9/8/2006 at 10:37 AM jim stephens wrote:
<>So, you've got a YD-802-4 drive under all
of the IBM skin, right? And
you're not using it with an IBM 3174 controller?
sorry, thought I had said I did have a 3174. I have a 3174-63R with
token ring, trying to bring up for TN3270 usage over the token ring
interface that is installed.
Jim
5:22 p.m.
Jim?? wrote....
I am looking for the Microcode variety. I have a lot
of Drivetec media,
but I am not certain that is what is needed for the 2.4mb drives.
I missed this thread.... are you looking for the microcode floppies for 3174
at config level C to use TN3270? If so, don't spend a lot of time looking
for them, cause you can call IBM's microcode division and get a free set of
disks. No licensing paperwork, no cost... just say you need a set and it'll
arrive in the mail. That's what I did to get my 3174 with TN3270 up and
running.
Jay
1:42 p.m.
On 9/8/2006 at 10:01 AM Mr Ian Primus wrote:
I've seen them used in IBM terminal controllers as
microcode floppies. The drives for said terminal
controllers are easy to find - I have many. Disks are
scarcer. I don't know if the IBM 2.4 meg disk is the
same as the ones used by the Kaypro. I also don't know
much about how the format works.
I think we're talking about two different technologies here. IBM used a
drive made by YE data that, while 80 cylinder, packed the data much more
densely on each track. The Drivetec variety used dual positioners in
connection with a servo track to get 160 cylinders (at 600 RPM).
In either case, floppies for them are pretty rare.
However, I wonder what would happen if one formatted the IBM variety using
a 3.5' 2.88MB-capable PC controller.
Cheers,
Chuck
3:25 p.m.
On Friday 08 September 2006 13:42, Chuck Guzis wrote:
On 9/8/2006 at 10:01 AM Mr Ian Primus wrote:
FWIW, I tried hooking one of these up to a catweasel 3 in a PC, and
while it could read "1.2MB" floppies just fine, I couldn't get Tim
Mann's catweasel utilities to recognize any MFM or other encoding on
the data stream that the catweasel card was reading off the 2.4MB disks
I've got (which are IBM 3174 microcode disks).
Pat
--
Purdue University Research Computing -- http://www.itap.purdue.edu/rcac
I've seen them used in IBM terminal
controllers as
microcode floppies. The drives for said terminal
controllers are easy to find - I have many. Disks are
scarcer. I don't know if the IBM 2.4 meg disk is the
same as the ones used by the Kaypro. I also don't know
much about how the format works.
I think we're talking about two different technologies here. IBM
used a drive made by YE data that, while 80 cylinder, packed the data
much more densely on each track. The Drivetec variety used dual
positioners in connection with a servo track to get 160 cylinders (at
600 RPM).
In either case, floppies for them are pretty rare.
However, I wonder what would happen if one formatted the IBM variety
using a 3.5' 2.88MB-capable PC controller. 
5:23 p.m.
On Friday 08 September 2006 13:42, Chuck Guzis wrote:
On 9/8/2006 at 10:01 AM Mr Ian Primus wrote:
FWIW, I tried hooking one of these up to a catweasel 3 in a PC, and
while it could read "1.2MB" floppies just fine, I couldn't get Tim
Mann's catweasel utilities to recognize any MFM or other encoding on
the data stream that the catweasel card was reading off the 2.4MB disks
I've got (which are IBM 3174 microcode disks).
Pat
--
Purdue University Research Computing -- http://www.itap.purdue.edu/rcac
--
Purdue University Research Computing --- http://www.rcac.purdue.edu/
The Computer Refuge --- http://computer-refuge.org
I've seen them used in IBM terminal
controllers as
microcode floppies. The drives for said terminal
controllers are easy to find - I have many. Disks are
scarcer. I don't know if the IBM 2.4 meg disk is the
same as the ones used by the Kaypro. I also don't know
much about how the format works.
I think we're talking about two different technologies here. IBM
used a drive made by YE data that, while 80 cylinder, packed the data
much more densely on each track. The Drivetec variety used dual
positioners in connection with a servo track to get 160 cylinders (at
600 RPM).
In either case, floppies for them are pretty rare.
However, I wonder what would happen if one formatted the IBM variety
using a 3.5' 2.88MB-capable PC controller.
5:53 p.m.
On 9/8/2006 at 5:23 PM Patrick Finnegan wrote:
FWIW, I tried hooking one of these up to a catweasel 3
in a PC, and
while it could read "1.2MB" floppies just fine, I couldn't get Tim
Mann's catweasel utilities to recognize any MFM or other encoding on
the data stream that the catweasel card was reading off the 2.4MB disks
I've got (which are IBM 3174 microcode disks).
A Catweasel histogram of a track of one of these might shine a little light
on the recording technique used. Could be CGR or even a flavor of RLL.
But isn't this drive on the 3174 read-only?
Cheers,
Chuck
9 Sep
9 Sep
11:26 a.m.
On Friday 08 September 2006 17:53, you wrote:
On 9/8/2006 at 5:23 PM Patrick Finnegan wrote:
Actually it's not read only. It's just used that way most of the time.
I'm using a couple of drives from a cluster controller. I had to figure out
how the 2.4 meg worked...
They have a two speed spindle 360/180 rpm and use 500kbit mfm just like
8" dd disks.
2.4 meg. only works on "microcode" disks though. And they are pretty scarce.
joe lang
FWIW, I tried hooking one of these up to a
catweasel 3 in a PC, and
while it could read "1.2MB" floppies just fine, I couldn't get Tim
Mann's catweasel utilities to recognize any MFM or other encoding on
the data stream that the catweasel card was reading off the 2.4MB disks
I've got (which are IBM 3174 microcode disks).
A Catweasel histogram of a track of one of these might shine a little light
on the recording technique used. Could be CGR or even a flavor of RLL.
But isn't this drive on the 3174 read-only?
Cheers,
Chuck
11:59 a.m.
On 9/9/2006 at 11:26 AM joseph c lang wrote:
They have a two speed spindle 360/180 rpm and use
500kbit mfm just like
8" dd disks. 2.4 meg. only works on "microcode" disks though. And they are
pretty
scarce.
This reminds me of one of the dodges offered early on in the PC to enable a
5150 or 5160 PC to handle 1.2M diskettes without swapping the controller
card--someone offered a dual-speed drive that spun at 300 and 180 RPM (not
to be confused with the 300/360 dual-speed 1.2M drives). Apparently it
worked, but I wondered how good the S/N ratio at the lower spindle speed
was. For a short time, it was either very expensive or next to impossible
to get a 1.2MB-capable controller for a 5150, since the PC/AT put the FDC
on the HDC board. The gap was quickly filled by outfits like Micro
Solutions and Sysgen (and then the Far East cloners) and the dual-speed
drives vanished.
Is the coating on the 2.4MB floppies a standard formulation? It would seem
to be a simple matter to format these things if that were true--assuming
the drive supports writing at the lower spindle speed.
Cheers,
Chuck
5:02 p.m.
They have a two
speed spindle 360/180 rpm and use 500kbit mfm just like
8" dd disks. 2.4 meg. only works on "microcode" disks though. And they are
pretty
>scarce. This reminds me of one of the dodges offered early on
in the PC to enable a
5150 or 5160 PC to handle 1.2M diskettes without swapping the controller
card--someone offered a dual-speed drive that spun at 300 and 180 RPM (not
to be confused with the 300/360 dual-speed 1.2M drives). Apparently it
worked, but I wondered how good the S/N ratio at the lower spindle speed
was.
Weltec was the best known of those. 180RPM drive designed for 600 Oersted
media at 250K data transfer rate. I know somebody who has one (if he can
find it). It worked, but reliability was noticeably lower than the real
thing.
At the 500K rate, it should work for the 2.4M.
But so would a "normal" 1.2M drive run at a 1000K data transfer rate
("2.8M")
For a short time, it was either very expensive or next
to impossible
to get a 1.2MB-capable controller for a 5150, since the PC/AT put the FDC
on the HDC board. The gap was quickly filled by outfits like Micro
Solutions and Sysgen (and then the Far East cloners) and the dual-speed
drives vanished.
I had 8" drives on 5150 before I had an AT.
Flagstaff Engineering, MicroTech Export, Vista, Maynard, Amlyn, Tall tree
(JDisk), etc.
Before the AT came out, there wasn't a solid standard for how mode
switching was controlled. And, before the AT, some of the 1.2M drives had
a 50 pin 8" style connector.
5:28 p.m.
On 9/9/2006 at 2:02 PM Fred Cisin wrote:
At the 500K rate, it should work for the 2.4M.
But so would a "normal" 1.2M drive run at a 1000K data transfer rate
("2.8M")
I'm not convinced of that, Fred. Most drive read circuitry has some sort
of low-pass filtering and I suspect that it would get in the way of a 1Mbps
data rate. At least that's what I've found with some of the older 5.25"
drives.
It shouldn't be hard to hack a "regular" 1.2MB drive to spin at 180 rpm so
2.4MB could be formatted, but the media formulation is what I'm curious
about.
I should have said "For a short time, it was either very expensive or next
to impossible to get a 1.2MB-capable PC/AT compatible controller for a
5150". In any case, even the non-hardware-compatible CompatiCard I/II or
the Tall Tree setups were pretty expensive. I can remember hacking a cheap
Taiwanese XT controller to handle 500Kbps media was the most
cost-effective.
Cheers,
Chuck
10 Sep
10 Sep
2:07 p.m.
On Saturday 09 September 2006 11:59, you wrote:
On 9/9/2006 at 11:26 AM joseph c lang wrote:
I suspect the disk coating is not the same as 1.2m disks. The 1.2m disks
have a high error rate when used at 2.4m.
The coating on the 2.4 meg diskettes is darker than the 1.2 meg disks.
It also appears to have a smoother surface. I know that doesn't prove
the coating is different, but I think it's a pretty safe bet.
joe lang
They have a two speed spindle 360/180 rpm and use
500kbit mfm just like
8" dd disks. 2.4 meg. only works on "microcode" disks though. And they are
pretty
scarce.
This reminds me of one of the dodges offered early on in the PC to enable a
5150 or 5160 PC to handle 1.2M diskettes without swapping the controller
card--someone offered a dual-speed drive that spun at 300 and 180 RPM (not
to be confused with the 300/360 dual-speed 1.2M drives). Apparently it
worked, but I wondered how good the S/N ratio at the lower spindle speed
was. For a short time, it was either very expensive or next to impossible
to get a 1.2MB-capable controller for a 5150, since the PC/AT put the FDC
on the HDC board. The gap was quickly filled by outfits like Micro
Solutions and Sysgen (and then the Far East cloners) and the dual-speed
drives vanished.
Is the coating on the 2.4MB floppies a standard formulation? It would seem
to be a simple matter to format these things if that were true--assuming
the drive supports writing at the lower spindle speed.
Cheers,
Chuck
6507
days inactive
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days old
15 comments
8 participants
participants (8)
-
cclist＠sydex.com -
cisin＠xenosoft.com -
ian_primus＠yahoo.com -
jclang＠notms.net -
jwest＠classiccmp.org -
jwstephens＠msm.umr.edu -
pat＠computer-refuge.org -
vax＠purdue.edu