11 Oct
2008
11 Oct
'08
11:34 a.m.
Was wondering if 3.5" HD floppy drives can be jumpered/used in
a system that only supports 720K, using them as 720K only
drives ?
I only own one 720K floppy drive (wouldn't mind a few more).
If that is possible, and only possible with some drives, anyone know
if it is possible with any of the following:
Panasonic JU-257A827P
Panasonic JU-256A216P
Sony MP-F17W-09 SMM
Samsung SFD-321D/T
Epson SMD-1300
TEAC FD-235HF
Also, anyone know if there if it is possible to slow the spindle speed
so that 1.44M can be done on machines that only have DD data rate ?
(and if so, any of the above drives capable of being slowed ?) Would
that even work ?
-- Curt
11 Oct
11 Oct
11:59 a.m.
Curtis H. Wilbar Jr. wrote:
Was wondering if 3.5" HD floppy drives can be jumpered/used in
a system that only supports 720K, using them as 720K only
drives ?
I only own one 720K floppy drive (wouldn't mind a few more).
If that is possible, and only possible with some drives, anyone know
if it is possible with any of the following:
Standard PC 1.44M drives will work fine as 720K drives as long as you
ONLY use 720K DD media, most drives auto detect the media and adjust the
data rate accordingly. The same is not true however for 1.2M 5.25"
drives which IIRC must be told what rate to operate at, as the spindle
speed is higher for 1.2M, and there is no density select hole as there
is on 720K/1.44M.
There are a couple of problems however, most 1.44M drives are jumpered
to operate as drive 1 only, and cannot easily be changed, this can be
fixed however by swapping lines in the cable e.g. swapping 10 and 12
will make the drive respond as drive 0.
Also depending on your system, it may require a ready signal on Pin 34,
most 1.44M drives supply disk change on this pin, however the couple of
systems I have worked with that require this signal (Amstrad CPC,
Spectrum +3), wiring the signal permenently to ground will do the trick.
Note some of the older 1.44s may have jumpers to change the ID, and
enable ready. I have some Teac FD-235F drives that are like this (they
have a bunch of jimpers just to the left of the steper motor),
unfortunatly the HF that you have does not.
Also, anyone know if there if it is possible to slow
the spindle speed
so that 1.44M can be done on machines that only have DD data rate ?
(and if so, any of the above drives capable of being slowed ?) Would
that even work ?
Unfortunatly I believe that the spindle speed in 1.44s is always 300rpm,
even when operating in HD mode, and that is fixed in the drive, I don't
think that's possible (with standard drives at least).
Cheers.
Phill.
--
Phill Harvey-Smith, Programmer, Hardware hacker, and general eccentric !
"You can twist perceptions, but reality won't budge" -- Rush.
2:11 p.m.
On Saturday 11 October 2008 11:59, Phill Harvey-Smith wrote:
There are a couple of problems however, most 1.44M
drives are jumpered
to operate as drive 1 only, and cannot easily be changed, this can be
fixed however by swapping lines in the cable e.g. swapping 10 and 12
will make the drive respond as drive 0.
Hence the twist in the cable...
Also depending on your system, it may require a ready
signal on Pin 34,
most 1.44M drives supply disk change on this pin, however the couple of
systems I have worked with that require this signal (Amstrad CPC,
Spectrum +3), wiring the signal permenently to ground will do the trick.
I have somewhere several of those adapters that were suppled to convert the
pin-type connectors common on 3.5" drives to the edge connector common on
floppy cables supplied for earlier drives, and some of these at least have a
jumper on them that I would guess allows for selecting this. At least I know
that it does *something* with regard to pin 34 (Curtis, let me know if you
need one... :-).
Note some of the older 1.44s may have jumpers to
change the ID, and
enable ready. I have some Teac FD-235F drives that are like this (they
have a bunch of jimpers just to the left of the steper motor),
unfortunatly the HF that you have does not.
I am going to have to look through the floppy drives I have on hand and see
which models they are and which might offer some flexibility and which
don't. :-)
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
2:37 p.m.
Roy J. Tellason wrote:
On Saturday 11 October 2008 11:59, Phill Harvey-Smith
wrote:
Sort of, to use a 1.44 as a normal drive you only need to exchange pins
10 and 12 (which are the drive select lines), and not move the motor on
line. The normal PC cable twist exchanges both.
Cheers.
Phill.
--
Phill Harvey-Smith, Programmer, Hardware hacker, and general eccentric !
"You can twist perceptions, but reality won't budge" -- Rush.
There are a couple of problems however, most
1.44M drives are jumpered
to operate as drive 1 only, and cannot easily be changed, this can be
fixed however by swapping lines in the cable e.g. swapping 10 and 12
will make the drive respond as drive 0.
Hence the twist in the cable...
2:49 p.m.
On Saturday 11 October 2008 14:37, Phill Harvey-Smith wrote:
Roy J. Tellason wrote:
Ah.
There was a time a while back when guy brought me a homebrew Xerox 820-1
system that had two different brands of 5.25" floppies in it, and I had what
it took going on in my head at the time to look at all of the lines and
whatnot and make it work.
Somewhere around the time peecee hardware started to take over I started
seeing less and less of those sorts of challenges, so those particular brain
cells have been sound asleep for a while now. :-)
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
On Saturday 11 October 2008 11:59, Phill
Harvey-Smith wrote:
Sort of, to use a 1.44 as a normal drive you only need to exchange pins
10 and 12 (which are the drive select lines), and not move the motor on
line. The normal PC cable twist exchanges both. There are a couple of problems however, most
1.44M drives are jumpered
to operate as drive 1 only, and cannot easily be changed, this can be
fixed however by swapping lines in the cable e.g. swapping 10 and 12
will make the drive respond as drive 0.
Hence the twist in the cable... 
3:11 p.m.
On 11 Oct 2008 at 16:59, Phill Harvey-Smith wrote:
Also depending on your system, it may require a ready
signal on Pin 34,
most 1.44M drives supply disk change on this pin, however the couple of
systems I have worked with that require this signal (Amstrad CPC,
Spectrum +3), wiring the signal permenently to ground will do the trick.
And often cause the system to hang without a diskette in the drive,
unless there's some sort of deadman timer on I/O operations. There
are also a few systems out there that have software to interrupt on
ready-to-not-ready transitions to determine if a disk-changed
condition should be checked for--but you mostly see this on systems
with 8" drives with line-powered spindle motors. We just polled the
write-protect sensor on old 5.25" drives to do the same thing.
On many of those 34-conductor 5.25-3.5 adapters, the jumper for disk
change switches between pin 34 and nothing. A drive with a pin 34
READY output on a PC that's expecting disk-change instead creates
problems.
Cheers,
Chuck
Note some of the older 1.44s may have jumpers to change the ID, and
enable ready. I have some Teac FD-235F drives that are like this (they
have a bunch of jimpers just to the left of the steper motor),
unfortunatly the HF that you have does not.
Also, anyone know if there if it is possible to
slow the spindle speed
so that 1.44M can be done on machines that only have DD data rate ?
(and if so, any of the above drives capable of being slowed ?) Would
that even work ?
Unfortunatly I believe that the spindle speed in 1.44s is always 300rpm,
even when operating in HD mode, and that is fixed in the drive, I don't
think that's possible (with standard drives at least).
Cheers.
Phill.
--
Phill Harvey-Smith, Programmer, Hardware hacker, and general eccentric !
"You can twist perceptions, but reality won't budge" -- Rush. 
4:17 p.m.
[Disk Change]
with 8" drives with line-powered spindle motors.
We just polled the
write-protect sensor on old 5.25" drives to do the same thing.
The HP9836 system that I've been working on has a pair of 5.25" drives
which are effectively permanently enabled (the 'MX' jumper is fitted) and
thus have spearate cables back to the contoller board. The write-protect
lines trigger flip-flops for a disk change function (as well, of course,
as being used for the write protect function) while the index lines also
trigger retriggerable monostables for a ready function (if index pulses
are happening sufficiently often, there must be a disk in the drive, it
must be turning).
-tony
5:20 p.m.
On 11 Oct 2008 at 21:17, Tony Duell wrote:
The HP9836 system that I've been working on has a
pair of 5.25" drives
which are effectively permanently enabled (the 'MX' jumper is fitted) and
thus have spearate cables back to the contoller board. The write-protect
lines trigger flip-flops for a disk change function (as well, of course,
as being used for the write protect function) while the index lines also
trigger retriggerable monostables for a ready function (if index pulses
are happening sufficiently often, there must be a disk in the drive, it
must be turning).
I've got some 5.25" MPI drives with a separate "ready" board that
plugs into the main drive electronics board. It's got a 96L02 dual
one-shot and some discretes to form a ready circuit.
One of the problems with add-on ready circuits on the controller side
of the select circuitry is that determinining ready has to involve
enough time (3 revs usually) to make sure that spindle's up to speed.
Unfortunately, this creates a delay every time one changes drive
select. Conditioning the READY off of the motor signal is no
guarantee, as some drives disable the motor when there's no diskette
in the drive. So leaving drives always selected as you describe is a
way around the problem.
We were plagued by customers simply changing diskettes whenever they
felt like it. Relying on a checksum-after-select scheme such as that
used by CP/M and early MS-DOS versions was pretty ugly (and not at
all airtight, something that plagued MICROSO~1 no end). While
playing with the driver, I noted that the write protect signal was
conditioned only on select, not on motor, head-load or ready.
Experimenting with some of the other engineers to see how fast one
could insert and remove a floppy gave a safe polling interval of
about 250 msec, which was barely noticeable in normal system
operation and performed only if there were open files on the drive.
Some of the single-sided 600 RPM Sony (0A1?) drives were also used in
a few CP/M systems, such as the Preis. It was a very noticeable
improvement over 5.25" media.
Cheers,
Chuck
8:04 p.m.
On Sat, 11 Oct 2008, Chuck Guzis wrote:
We were plagued by customers simply changing diskettes
whenever they
felt like it. Relying on a checksum-after-select scheme such as that
used by CP/M and early MS-DOS versions was pretty ugly (and not at
all airtight, something that plagued MICROSO~1 no end).
Why didn't MICROS~1 ever document that the CPM ^C was fully enabled to
flush the disk buggers?
While
playing with the driver, I noted that the write
protect signal was
conditioned only on select, not on motor, head-load or ready.
Experimenting with some of the other engineers to see how fast one
could insert and remove a floppy gave a safe polling interval of
about 250 msec, which was barely noticeable in normal system
operation and performed only if there were open files on the drive.
Some of the single-sided 600 RPM Sony (0A1?) drives were also used in
a few CP/M systems, such as the Preis. It was a very noticeable
improvement over 5.25" media.
Cheers,
Chuck
--
Fred Cisin cisin at xenosoft.com
XenoSoft http://www.xenosoft.com
PO Box 1236 (510) 558-9366
Berkeley, CA 94701-1236
6:51 p.m.
> Why didn't MICROS~1 ever document that the
CPM ^C was fully enabled to
> flush the disk buggers?
On Sun, 12 Oct 2008, Tony Duell wrote:
I've made that typo many times, but fortunately I
think I've always
caught it before sending the e-mail...
Considering the OS, the situation (OS using WRONG buffered content for
disk I/O), the possible consequences, and the complete failure to ever
document the problem and/or the work-around, I might be able to try to
claim that it wasn't a typo :-(
7:15 p.m.
On 12 Oct 2008 at 15:51, Fred Cisin wrote:
Considering the OS, the situation (OS using WRONG
buffered content for
disk I/O), the possible consequences, and the complete failure to ever
document the problem and/or the work-around, I might be able to try to
claim that it wasn't a typo :-(
No, I don't know. Microsoft does say in the documentation for INT
21H, function 0DH ("Reset disk") that "Function ODH should be part of
Control-C interrupt handling routines so that the system is in a
known state when an application is terminated." However, ISTR that
after some point MS-DOS, this function didn't flush *all* buffers.
(I'm quoting from a MS-DOS 2.10 reference).
It could be that Ctrl-C, even at a command prompt didn't always do
what it was supposed to and Microsoft didn't care to document this
"feature".
Cheers,
Chuck
11 Oct
11 Oct
1:29 p.m.
On 11 Oct 2008 at 11:34, Curtis H. Wilbar Jr. wrote:
Was wondering if 3.5" HD floppy drives can be
jumpered/used in
a system that only supports 720K, using them as 720K only
drives ?
Without running down my documentation on the drives, here's an
approximate answer.
Any 1.44MB drive will read and write 720K diskettes just fine (as you
probably already know). However, using one as a 720K-only drive or
to replace a 720K drive has a few issues, some of which can be
resolved by reconfiguring the drive, sometimes not. For example,
there are *many* variations on the Teac FD235HF; newer drives tend to
be less configurable (or more difficult to configure) than older
ones.
The first issue is to get the drive to ignore the difference between
1.44MB and 720KB media (i.e. the media type aperture in the floppy
jacket). If a drive could be configured to operate in "host media
select" (also sometimes called "PS/2 mode") where the media type is
signalled by driving pin 2 on the floppy interface, it's possible to
get the drives to ignore the aperture. Otherwise, you have to use
care to make sure that if you're using 1.44MB media as 720KB, the
aperture is covered over.
The second is the function of pin 34. The normal (PC) function of
this pin is as a "disk changed" indicator; but some drives allowed
for redefining this pin as "ready", which is the 720K convention.
I've done that with Sony 1.44MB drives and know that it was a jumper
option for some Teac models.
If you've got one, also check out the Teac FD235J (2.88MB drive).
Some models of this drive had jumpers for just about anything you
could imagine, including media select and ready-vs-disk change.
Also, anyone know if there if it is possible to slow
the spindle speed
so that 1.44M can be done on machines that only have DD data rate ?
(and if so, any of the above drives capable of being slowed ?) Would
that even work ?
While it's possible to change the spindle speed on many 1.44MB
drives, the speed change is to 360 RPM from 300 RPM. As far as
slowing the spindle speed to 150 RPM, while it might be possible with
some hacking, you wouldn't like the result. Read signal strength on
a disk drive is proportional to the square of the speed of the medium
passing by the head; halving the drive speed quarters the read signal
level (one of the reasons, but not the only one, that inner tracks on
a diskette tend to be less reliable than outer ones).
In the early days of the PC AT, there were some offerings of 5.25"
drives with 180 RPM spindle speeds to allow them to be used with a PC
XT diskette controller for 1.2MB media. They barely worked at all.
Cheers,
Chuck
7:50 p.m.
Chuck Guzis wrote:
The first issue is to get the drive to ignore the
difference between
1.44MB and 720KB media
I think drives nearly always do the detection via a microswitch, don't they?
(It wouldn't surprise me if at least one wasn't using some kind of optical
arrangement). In the event of no jumper, cutting traces or bridging switch
pins with solder should do the job I would have thought.
cheers
Jules
8:12 p.m.
> The first issue is to get the drive to ignore the
difference between
> 1.44MB and 720KB media
On Sat, 11 Oct 2008, Jules Richardson wrote:
I think drives nearly always do the detection via a
microswitch, don't they?
Some use a microswitch, some use a photocell, some (early PS/2) have NO
detection hardware.
8:18 p.m.
Jules Richardson wrote:
Chuck Guzis wrote:
IBM PS/2s did it optically.
Peace... Sridhar
The first issue is to get the drive to ignore the
difference between
1.44MB and 720KB media
I think drives nearly always do the detection via a microswitch, don't
they? (It wouldn't surprise me if at least one wasn't using some kind of
optical arrangement). In the event of no jumper, cutting traces or
bridging switch pins with solder should do the job I would have thought. 
11:47 p.m.
--- On Sat, 10/11/08, Sridhar Ayengar <ploopster at gmail.com> wrote:
microswitch, don't
Hehe. Or not at all... I remember using one PS/2 that just assumed everything was HD
unless told otherwise (or the disk was already readable). Didn't even need to drill
holes in the disks to 'upgrade' them. Of course, these days, I find myself taping
over the holes in disks, since DD media is hard to find.
I've made high density 5 1/4" drives into 80 track double density (720K) drives
by cutting the trace on the board that leads to pin 2, and tying it to ground. This forces
the drive into DD recording.
Never tried it with a 3 1/2" drive.
Now, what I wonder, is how does the _controller_ know what kind of disk is inserted in the
drive? According to the documentation I have, the density select line is defined as a
unidirectional signal TO the drive, not from it. Having not worked as much with 3
1/2" drives, I don't know, but I would assume that the drive senses the
disk's hole, and operates in that data rate and density recording, and the computer
simply picks up on the data rate and works accordingly. Or, perhaps, in 3 1/2"
drives, pin 2 is bidirectional, allowing the drive to tell the computer the type of disk
inserted. I don't know.
But, 1.44mb floppy drives are cheap and easy to get. Grab a soldering iron and try it :)
-Ian
> The first
issue is to get the drive to ignore the
difference between
1.44MB
and 720KB media
I think drives nearly always do the detection via a they? (It wouldn't surprise me if at least
one
wasn't using some kind of
optical arrangement). In the event of no jumper,
cutting traces or
bridging switch pins with solder should do the
job I
would have thought.
IBM PS/2s did it optically.
12 Oct
12 Oct
12:23 a.m.
On 11 Oct 2008 at 20:47, Mr Ian Primus wrote:
At one time, diskette "punchers" were a popular item at computer swap
meets. The price differential between HD and DD media at one point
was substantial. I think I paid over $50 for my first box of 10 Fuji
DSHD 3.5" diskettes. I found it easier just to stack up a bunch of
DD diskettes on my drill press and drill a hole through the entire
stack.
IBM PS/2s did
it optically.
Hehe. Or not at all... I remember using one PS/2 that just assumed
everything was HD unless told otherwise (or the disk was already
readable). Didn't even need to drill holes in the disks to 'upgrade'
them. Of course, these days, I find myself taping over the holes in
disks, since DD media is hard to find. I've made high density 5 1/4" drives into 80
track double density
(720K) drives by cutting the trace on the board that leads to pin 2,
and tying it to ground. This forces the drive into DD recording.
You're leaving something out here. While that forces the drive into
DD recording mode, the spindle speed doesn't change unless the drive
is also jumpered for "dual-speed" 300/360 mode. So there can be a
real difference between a "fixed" drive and a genuine 720K DSQD
drive.
Now, what I wonder, is how does the _controller_ know
what kind of
disk is inserted in the drive? According to the documentation I have,
the density select line is defined as a unidirectional signal TO the
drive, not from it. Having not worked as much with 3 1/2" drives, I
don't know, but I would assume that the drive senses the disk's hole,
and operates in that data rate and density recording, and the computer
simply picks up on the data rate and works accordingly. Or, perhaps,
in 3 1/2" drives, pin 2 is bidirectional, allowing the drive to tell
the computer the type of disk inserted. I don't know.
Grab some documentation on early 1.44MB drives. You could often
configure them for "auto sense" (the way most recent drives are by
default) or "remote sense" in which the status of the media sensor is
fed back to the host and the host selects the density via pin 2. Or
do it the way the PS/2 did and ignore the media type completely.
Some drives are smarter than others. Most 3.5" USB drives will
automatically sense 1.23MB media and adjust the spindle speek
accordingly (they do not, however allow formatting of 1.23MB media).
I've got a "legacy" interface drive from Toshiba that will also do
the same. Appropriately configured 3.5" Teac GF and some HF drives
can use a signal on pin 4 to change spindle speeds.
There's more variation among HD 3.5" drive signals that most people
realize, particularly in Japanese variants, where conventions used in
the NEC 9801 held sway. A bog-standard 1.44MB PC drive will often
refuse to work in that architecture. The 9801 used a very sane
approach to diskettes--the format of an 8" diskette is exactly the
same as the 5.25" and 3.5" varieties--77 cylinders, 2 sides, 8
sectors per side, 1024 bytes per sector and 360 RPM.
Cheers,
Chuck
8:16 a.m.
--- On Sun, 10/12/08, Chuck Guzis <cclist at sydex.com> wrote:
I remember seeing the punchers, but I never had one. I just used a hand drill, and drilled
them one at a time. I also had a couple that I had needed to convert at the computer lab
at school - which I did by cutting that corner off the disk with a paper cutter...
You're right. I am leaving something out. I also changed a jumper on the drive to do
that. And, on one drive, I had to mess with the wiring of the spindle motor. Thanks for
reminding me.
readable).
Didn't even need to drill holes in the
disks to 'upgrade'
them. Of course, these days, I find myself taping
over
the holes in
disks, since DD media is hard to find.
At one time, diskette "punchers" were a popular
item at computer swap
meets. The price differential between HD and DD media at
one point
was substantial. I've made
high density 5 1/4" drives into 80
track double density
(720K) drives by cutting the trace on the board
that
leads to pin 2,
and tying it to ground. This forces the drive
into DD
recording.
You're leaving something out here. While that forces
the drive into
DD recording mode, the spindle speed doesn't change
unless the drive
is also jumpered for "dual-speed" 300/360 mode.
So there can be a
real difference between a "fixed" drive and a
genuine 720K DSQD
drive. Grab some documentation on early 1.44MB drives. You
could
often
configure them for "auto sense" (the way most
recent drives are by
default) or "remote sense" in which the status of
the media sensor is
fed back to the host and the host selects the density via
pin 2. Or
do it the way the PS/2 did and ignore the media type
completely.
Ah. that makes sense. I figured that there had to be some kind of function for that.
-Ian
2:51 a.m.
Chuck Guzis wrote:
Those full-height Sonys that I mentioned (which don't, of course, handle
HD media [1]) use mechanical sesnors for disk-inserted and write-protect,
which move little plastic 'flags' into slotted optoswitches. It wouldn't
suprise me if at least one HD sensor worked that way.
[1] The disk-inserted sensor pin lines up with the position of the 'HD
hole' so the drive thinks it has no disk if an HD one is put in. I have
been told this was deliberate, the HD media is of a higher coercivity
than the DD (altough much closer than the differnce between DD and HD
5.25" diks), so using the wrong disk may well not be reliable.
The first issue is to get the drive to ignore the
difference between
1.44MB and 720KB media
I think drives nearly always do the detection via a microswitch, don't they?
(It wouldn't surprise me if at least one wasn't using some kind of optical
arrangement). In the event of no jumper, cutting
traces or bridging switch
pins with solder should do the job I would have thought.
If the sensor is optical, then the same methods apply (cut a trace to
force it 'dark', short the phototransistor to force it 'light').
-tony
11 Oct
11 Oct
1:38 p.m.
On Sat, 11 Oct 2008, Curtis H. Wilbar Jr. wrote:
Was wondering if 3.5" HD floppy drives can be
jumpered/used in
a system that only supports 720K, using them as 720K only
drives ?
yes
Also, anyone know if there if it is possible to slow
the spindle speed
so that 1.44M can be done on machines that only have DD data rate ?
(and if so, any of the above drives capable of being slowed ?) Would
that even work ?
Nobody has successfully used a 3.5" at 150RPM. Yet.
Besides the "normal" 300RPM drives, there are some 600RPM (old Sony), and
360RPM (NEC and a few others)
3:06 p.m.
Fred Cisin wrote:
Nobody has successfully used a 3.5" at 150RPM.
Yet.
Besides the "normal" 300RPM drives, there are some 600RPM (old Sony), and
360RPM (NEC and a few others)
What about the old Amiga high-density drives that ran at 300RPM for DSDD and
150RPM for DSHD?
The story I heard was that it worked out cheaper for CBM to get a bunch of
speed-switching floppy drives made up instead of modifying the disc controller
to support multiple data rates. I'm not sure I believe that...
But yes, there were 600RPM 3.5" drives -- some Hewlett-Packard logic analysers
(1650A/B series mainly, IIRC) used them.
--
Phil.
classiccmp at philpem.me.uk
http://www.philpem.me.uk/
3:37 p.m.
But yes, there were 600RPM 3.5" drives -- some
Hewlett-Packard logic analysers
(1650A/B series mainly, IIRC) used them.
IIRC, the original Sony 3.5" drive was a 600RPM unit. Originally it was a
single-sided unti, later there was a very similar double-sided one.
These drives are not uncommon in classic computers -- HP used them a lot
-- not just in logic analysers, but also in many of their floppy drive and
hard/floppy drive units (HP9121, 9122, 9133V, 9133XV, 9133H, Integral PC,
9114A -- and that's just the ones I can see from here!). They are also
used in at least some models of Apricot PC.
There's a half-height ('slimline') Sony 600 RPM drive too, It shares many
components with the Apple 800K drive (the main difference is in the
control logic ASIC). It was used, for example, in the HP9114B.
The HP9123 (dual foppy drive for the HP150-II) normally used the earlier
DS drives, but I've seen one with slimline drives. The PCB has pads for
both types of connector, there's a DIP switch to tell the firmware which
drives are fitted.
And yes I've repaired just about all of the above drives at some time or
another...
-tony
7:48 p.m.
> Nobody has successfully used a 3.5" at
150RPM. Yet.
On Sat, 11 Oct 2008, Philip Pemberton wrote:
What about the old Amiga high-density drives that ran
at 300RPM for DSDD and
150RPM for DSHD?
Sorry, I forgot about them.
I've never had any Amigas THAT new.
The story I heard was that it worked out cheaper for
CBM to get a bunch of
speed-switching floppy drives made up instead of modifying the disc controller
to support multiple data rates. I'm not sure I believe that...
It also provided a way to retrofit to machines that didn't support the
higher (1000bps) data transfer rate. The Weltek 180 RPM 5.25" drive
provided 1.2M support to XTs.
8:10 p.m.
On Oct 11, 2008, at 4:48 PM, Fred Cisin wrote:
One might argue that given the cool reception the users had to that
particular drive, it wasn't successful in the Amiga either.
ok
bear
> Nobody has
successfully used a 3.5" at 150RPM. Yet.
On Sat, 11 Oct 2008, Philip Pemberton wrote:
What about the old Amiga high-density drives that
ran at 300RPM for
DSDD and
150RPM for DSHD?
Sorry, I forgot about them.
I've never had any Amigas THAT new. 
11:47 p.m.
On Sat, Oct 11, 2008 at 05:10:30PM -0700, r.stricklin wrote:
On Oct 11, 2008, at 4:48 PM, Fred Cisin wrote:
One might argue that given the cool reception the users had to that
particular drive, it wasn't successful in the Amiga either.
I have several - one in my A4000 and at least one in a couple of A3000s.
They were, to me, essential, for trading things between PCs and Amigas
before everyone had a network card and/or was on the Internet.
ISTR they were well over $100 each, so I only bought one for each of
the machines that got daily use. I don't recall any reliability problems
with them that weren't cheap-media related.
The "nice" thing about them is that they are (electrically) compatible
with every Amiga made. I can't guarantee that they fit inside every
case style as FD0:, but you can plug them in and they will work, right
back to a 1985 A1000.
-ethan
--
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Ethan.Dicks at usap.gov http://penguincentral.com/penguincentral.html
>Nobody
has successfully used a 3.5" at 150RPM. Yet.
On Sat, 11 Oct 2008, Philip Pemberton wrote:
What about the old Amiga high-density drives that
ran at 300RPM for
DSDD and
150RPM for DSHD?
Sorry, I forgot about them.
I've never had any Amigas THAT new. 
12 Oct
12 Oct
5:30 a.m.
On Sat, 11 Oct 2008, Fred Cisin wrote:
Nobody has successfully used a 3.5" at 150RPM.
Yet.
All Amigas with HD floppy drives run HD media at 150RPM. Commodore used
Chinon drives which would change speed according to the HD hole in the
floppy jacket. And I have never had any problems with HD floppies on my
Amiga. Altough the transfer rate is only half of an HD floppy on most
other systems, it is nice to squeeze 1.9MB on a floppy (depending on the
file system and trackdisk.device replacement). BTW it's working since 1992
(that's when I got my A3000).
Christian
14 Oct
14 Oct
8:51 a.m.
On Sat, 11 Oct 2008, Fred Cisin wrote:
That's not entirely correct. Amiga 3000 and 4000 machines had a Chinon
drive mechanism that could run at 1/2 speed in order to write hi-density
formats with an FDC chip no capable of running at high data rates.
--
Also, anyone
know if there if it is possible to slow the spindle speed
so that 1.44M can be done on machines that only have DD data rate ?
(and if so, any of the above drives capable of being slowed ?) Would
that even work ?
Nobody has successfully used a 3.5" at 150RPM. Yet.
Besides the "normal" 300RPM drives, there are some 600RPM (old Sony), and
360RPM (NEC and a few others)
15 Oct
15 Oct
8:42 p.m.
Steven Hirsch wrote:
On Sat, 11 Oct 2008, Fred Cisin wrote:
That's not entirely correct. Amiga 3000 and 4000 machines had a
Chinon drive mechanism that could run at 1/2 speed in order to write
hi-density formats with an FDC chip no capable of running at high data
rates.
Is the interface on those drives compatable enough with non
Amiga equipment such that if you had one, you could it on a
'double density' controller and do HD ? Or did Amiga 'mangle'
the interface too far from standard ? Did the drive adjust speed
on it's own (by detecting the HD hole) or did the Amiga have to
tell it what speed to run ?
-- Curt
Also,
anyone know if there if it is possible to slow the spindle speed
so that 1.44M can be done on machines that only have DD data rate ?
(and if so, any of the above drives capable of being slowed ?) Would
that even work ?
Nobody has successfully used a 3.5" at 150RPM. Yet.
Besides the "normal" 300RPM drives, there are some 600RPM (old Sony),
and
360RPM (NEC and a few others)
16 Oct
16 Oct
4:41 a.m.
On Wed, 15 Oct 2008, Curtis H. Wilbar Jr. wrote:
Steven Hirsch wrote:
> That's not entirely correct. Amiga 3000 and 4000 machines had a Chinon
> drive mechanism that could run at 1/2 speed in order to write hi-density
> formats with an FDC chip no capable of running at high data rates.
That's what I said.
Is the interface on those drives compatable enough
with non
Amiga equipment such that if you had one, you could it on a
'double density' controller and do HD ? Or did Amiga 'mangle'
Yes, it it a standard Shugart bus drive, jumpered with /RDY on pin 34 and
/DC on pin 2.
the interface too far from standard ? Did the drive
adjust speed
on it's own (by detecting the HD hole) or did the Amiga have to
tell it what speed to run ?
The drive does it on its own.
Christian
11 Oct
11 Oct
3:03 p.m.
Thanks all for the input.... so, if I understand it correctly I should
be able to use any of these drives (other than the drive select and
drive ready signal issue) as a 720K drive. I'd be using 720K media,
so I'd imagine I don't need to worry about 'faking' out the HD sensor.
Out of the drives I listed, are any of the makes/models considered
good drives or lemon drives.... (would like to wee out lemons).
(I know I had mixed luck with TEAC drives... as I recall issues about
the sensor switches going up in resistance... I remember popping
the backs off the switches on one and cleaning them up inside and
restoring proper operation of the drive).
Curtis H. Wilbar Jr. wrote:
Panasonic JU-257A827P
Panasonic JU-256A216P
Sony MP-F17W-09 SMM
Samsung SFD-321D/T
Epson SMD-1300
TEAC FD-235HF
And I think I have a few of the adapters around for IDC to edge
connector... and I think at least one has a jumper or two... any idea
what those do ? (drive ready vs disk change ?)
Thanks,
-- Curt
3:24 p.m.
On 11 Oct 2008 at 15:03, Curtis H. Wilbar Jr. wrote:
Out of the drives I listed, are any of the
makes/models considered
good drives or lemon drives.... (would like to wee out lemons).
(I know I had mixed luck with TEAC drives... as I recall issues about
the sensor switches going up in resistance... I remember popping
the backs off the switches on one and cleaning them up inside and
restoring proper operation of the drive).
Older Teac drives are better(and generally more configurable) than
the cost-reduced newer ones. I find that NEC and Toshiba drives,
particularly the older ones are pretty good. My experiences with
Sony, Chinon and Epson have been variable.
Cheers,
Chuck
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