Need source of 80-track 5-1/4" drives
Lee Hart
them is getting progressively worse, and I would like to replace it.
Does anyone know of a source of 5-1/4" 80-track double-sided floppy
drives, this model or an equivalent, either full or half-height? These
were sometimes also called "96tpi", "quad density" or "800k" drives.
--
Lee A. Hart Ring the bells that still can ring
814 8th Ave. N. Forget your perfect offering
Sartell, MN 56377 USA There is a crack in everything
leeahart_at_earthlink.net That's how the light gets in - Leonard Cohen
Larry Bledsoe,MD
Amardeep S Chana
drives and jumper them to 300rpm and double density operation.
"Lee Hart" <leea...@earthlink.net> wrote in message
news:3C3DF8...@earthlink.net...
Ralph E. Dodd
This is only a little off topic. A long time ago I saw disks that were
rated as "quad density". Does this mean that regular old double side double
density disks won't work in aa 80 track, 96 tpi drive? I have a 720k 5-1/4"
floppy for an Atari ST that I've never been able to get to work and the
manual never specified what type of disk to use. I've tried dsdd and dshd
with the same result (failure). What type to you use on your H89? TIA.
Ralph
"Lee Hart" <leea...@earthlink.net> wrote in message
news:3C3DF8...@earthlink.net...
Herb Johnson
720K (40 and 80 track) use at 300 RPM. One is for 1.2M (80 track) 360 RPM
use. One is called "double density", the other "high density", because
more data per inch for each track is written on the 1.2M media. The
number of tracks is not the issue, it is the data rate and the rotation
rate which determine the density of the data WRITTEN to the disk (density
in bits per inch, or more precisely flux reversals per inch, of track).
The same used to be true for 3.5 inch media; however it is difficult to
find "double density" 3.5 inch diskettes for sale. 5.25 inch media in
general are even more rare, and I suspect that even fewer of them are
360K.
It is possible that some disks were marketed as "720K" or "quad density",
in part because they were specifically formatted that way. To my
knowledge, the media was the same as 360K diskettes. I may be wrong,
someone with better memory would be informative.
Some additional info may be in the comp.os.cpm FAQ. A Web search will
find this FAQ and some additional comments.
Herb Johnson
Ralph E. Dodd (red...@home.com) wrote:
: Hello Lee,
: Ralph
: >
--
Herbert R. Johnson http://pluto.njcc.com/~hjohnson
hjoh...@pluto.njcc.com voice 609-771-1503, New Jersey USA
amateur astronomer and telescope tinkerer
reseller of classic Macs & accessories from Plus to PowerMac
S-100 & 8-inch drive manuals and parts, call for "Dr. S-100"
Michael J. Mahon
>If all else fails you can always get the cheap and plentiful TEAC 1.2MB
>drives and jumper them to 300rpm and double density operation.
The heads on a 1.2MB drive are still half the width of heads on lower-
density drives. This is an issue if disks initialized at lower density are
written to, and then interchanged with a lower-density drive--it won't
work.
>"Lee Hart" <leea...@earthlink.net> wrote in message
>news:3C3DF8...@earthlink.net...
>> I have a pair of Tandon TM-100-4 floppy drives on my Heath H89. One of
>> them is getting progressively worse, and I would like to replace it.
>> Does anyone know of a source of 5-1/4" 80-track double-sided floppy
>> drives, this model or an equivalent, either full or half-height? These
>> were sometimes also called "96tpi", "quad density" or "800k" drives.
-michael
Email: mjm...@aol.com
Home page: http://members.aol.com/MJMahon/
Harold Bower
>
> There are only two kinds of 5.25 inch diskette media. One is for 360k and
> 720K (40 and 80 track) use at 300 RPM. One is for 1.2M (80 track) 360 RPM
> use. One is called "double density", the other "high density", because
> more data per inch for each track is written on the 1.2M media. The
> number of tracks is not the issue, it is the data rate and the rotation
> rate which determine the density of the data WRITTEN to the disk (density
> in bits per inch, or more precisely flux reversals per inch, of track).
Correct. The data for "normal" Double-Density (MFM) 300 rpm is 250
kbps, while the 1.2M "High-Density" clocks at 500 kbps which is the same
as for 8" disks (MFM).
> It is possible that some disks were marketed as "720K" or "quad density",
> in part because they were specifically formatted that way. To my
> knowledge, the media was the same as 360K diskettes. I may be wrong,
> someone with better memory would be informative.
The "quad density" label was commonly used to differentiate 40-track
from 80-track when we used short labels. Common terminology was:
SSSD - Single-sided, Single-density (~100 kB or less)
SSDD - Single-sided, Double-density (~200 kB or less)
DSSD - Double-sided, Single-density (not used much, but ~200 kB or
less)
DSDD - Double-sided, Double-density (~400 kB or less, 360 kB for MS
DOS >2)
These all existed for 40-track drives, FM (single-density) and MFM
(double-density)
For 80-track drives, some folks added:
SSSD - As above, capacity ~200 kB or less
SSDD (also sometimes referred to as SSQD, Quad-density) - As above,
capacity ~400 kB or less
DSSD - Not often used, but ~400 kB or less
DSQD - Often used, Double-Sided Quad-density (~800 kB or less)
Very confusing, and not very accurate, but that is how I remember it.
Hal
Richard Plinston
>
> There are only two kinds of 5.25 inch diskette media. One is for 360k and
> 720K (40 and 80 track) use at 300 RPM. One is for 1.2M (80 track) 360 RPM
> use. One is called "double density", the other "high density", because
Single Density diskettes did exist using the same media as for SD 8" at
250Kb (single sided).
> more data per inch for each track is written on the 1.2M media. The
> number of tracks is not the issue, it is the data rate and the rotation
> rate which determine the density of the data WRITTEN to the disk (density
> in bits per inch, or more precisely flux reversals per inch, of track).
> It is possible that some disks were marketed as "720K" or "quad density",
> in part because they were specifically formatted that way. To my
> knowledge, the media was the same as 360K diskettes.
While it is true that the spec for non-HD media is the same it is not
true that all diskettes are usable on 80 track drives, or even on DS
drives.
80 track heads are only half the width of 40 track heads and the
inter-track gap is much less. Some diskette media will not record a
strong enough signal with the narrow heads, some will 'bleed' into the
next track. Diskettes made with this media will only work consistently
with 40 track drives and will be marked DSDD (or even SSSD). Media that
is certified to work on 80 track is marked DSQD or 'Quad-Density', I
have some here such as Nashua 'DS QD 96tpi MD2F' and Verbatim '2S/4D-MD
557-01'. These were not formatted in any way.
Michael C Finn
news:XKB%7.333825$ez.47...@news1.rdc1.nj.home.com...
> This is only a little off topic. A long time ago I saw disks that were
> rated as "quad density". Does this mean that regular old double side
double
5-1/4"
> floppy for an Atari ST that I've never been able to get to work and the
> manual never specified what type of disk to use. I've tried dsdd and dshd
> with the same result (failure). What type to you use on your H89? TIA.
I have a Sanyo MBC-1250 which uses 5 1/4 floppy drives with 80 tracks. I
once bought disks certified as DSQD, double sided quad density, and they
were very poor quality. I was always getting bad sector errors. However, a
good quality DSDD floppy disk made by Sony or Maxwell worked just fine in
these drives and although they were only certified for 48TPI, they did fine
when pushed to 96TPI and rarely did I have one develop bad sectors and be
unreadable.
Before 5 1/4 floppy disks went out of favor, they were commonly available as
double density and high density (IBM compatibles made use of these) and
occasionally you would see quad density like the ones I had bought at Radio
Shack.
A user group I belonged to had a H89 with one hard sector drive (hard sector
floppies were still around but not on store shelves), two 40 track drives
and one 80 track drive. I always used 40 track soft sector floppies in that
80 track drive at PACS CP/M SIG meetings without a problem.
I was advised to stay away from the DSHD media for those 80 track double
density drives but I forget the details why.
You didn't mention details of the failure. Perhaps the problem isn't the
media but the floppy drive in your ST?
Amardeep S Chana
news:20020111154952...@mb-cg.aol.com...
> Amardeep S Chana wrote:
>
> >If all else fails you can always get the cheap and plentiful TEAC 1.2MB
> >drives and jumper them to 300rpm and double density operation.
>
> The heads on a 1.2MB drive are still half the width of heads on lower-
> density drives. This is an issue if disks initialized at lower density
are
> written to, and then interchanged with a lower-density drive--it won't
> work.
>
No, their heads are exactly the same size as 80 track lower density drives
like Lee was originally asking for. You are confusing the issue with 40
track lower density drives.
Stewart & Leta Marshall
couple of good pulls up in the attic.
cheers, Stewart
j.cammell
after all. These older type of Floppy drives are very plentyful.
Jack
Axel Berger
>I have a 720k 5-1/4" floppy for an Atari ST that I've never been able to
>get to work and the manual never specified what type of disk to use.
There are several possible reasons for that, the most probable being
that Atari did not use drivers for some lines, the two drive selects
and side select IIRC, which worked fine wirh new 3.5" that only loaded
the bus with 3 kOhm, but not with 5.25" drives using the correct
Shugart specified 330 Ohm.
As to the media, 96 tpi should in theory and practice require better
quality and higher resolution than 48 tpi, but as stated by others,
good quality DD media will easily suffice. HD is something else - they
use a different magnetic medium requiring different a field from the
write head. HD drives switch this when changing from HD to DD operation
so need the correct media in each case. Punching or taping the hole on
3.5" media (5.25" have no hardware coding) may sometimes work but is
always less reliable.
Michael C Finn
news:XKB%7.333825$ez.47...@news1.rdc1.nj.home.com...
> This is only a little off topic. A long time ago I saw disks that were
> rated as "quad density". Does this mean that regular old double side
double
5-1/4"
> floppy for an Atari ST that I've never been able to get to work and the
Ralph E. Dodd
"Michael C Finn" <mike...@worldnet.att.net> wrote in message
news:sL608.82112$fe1.1...@bgtnsc06-news.ops.worldnet.att.net...
Michael,
The drive is a Master-5S made by Oceanic Electronics Corp. in 1988. It was
supposed to be new when I bought it and it looked new in the original
packaging etc. It has a Teac FD-55GFR drive in it. There's a switch to
select 40 or 80 track operation (360k or 720k). I don't have an Atari ST
setup right now for testing. Most of the time formatting a disk would fail.
Sometimes the ST would say that the format was successful but the disk was
always unreadable. I guess I could pop another FD-55GFR drive in it and see
if the original drive is bad. Atari didn't make 5-1/4 drives for the ST so
this was a bastard aftermarket setup. I always thought that the disks were
the problem. As soon as I have time I'll try another drive and see what
happens. Thanks for the response.
Ralph
Terry Gulczynski
H89 for several years, and NEVER saw a problem. They work just fine under
CP/M or HDOS. No software changes required, just a minor change to the
cable itself. Uses the 720K disks, but either a tab over a HD disk (1.44MB)
hole or a physical mod to the drive allows use of 1.44MB disks.
Obviously, disks are a dime a dozen (or close, anyway!) and available
everywhere.
Terry Gulczynski
"Lee Hart" <leea...@earthlink.net> wrote in message
news:3C3DF8...@earthlink.net...
Lee Hart
>
> Lee - Why not just replace them with 3.5" units? I've been using them
> on my H89 for several years, and NEVER saw a problem. They work just
> fine under CP/M or HDOS. No software changes required, just a minor
> change to the cable itself. Uses the 720K disks, but either a tab over
> a HD disk (1.44MB) hole or a physical mod to the drive allows use of
> 1.44MB disks.
That's a good idea, and one I've considered. However, I decided not to
make this change for a few reasons:
1. My concern is that the higher the density, the poorer the archival
quality of the media. If this is true, a 3-1/2" high-density disk
would be the worst choice for something that will still be readable
in the future. I have 20-year-old 5-1/4" disks that still work. I've
also had many 5-year-old 3-1/2" disks that *DON'T* work!
I don't know if this is just that newer stuff is built to lower
quality standards (to be cheap), or if there are more fundamental
reasons behind the apparent difference.
2. The second reason is that most 3-1/2" disk drives are built like
throwaway junk. I don't know what their long-term reliability is
likely to be. But I do have 25-year-old 8" drives and 20-year-old
5-1/4" drives that are built like tanks and still work.
3. The third reason is that keeping the 5-1/4" drives keeps it "stock".
This doesn't really matter yet as my Heathkits are not considered
collectible, but who knows! :-)
Lee Hart
> If all else fails you can always get the cheap and plentiful TEAC 1.2MB
> drives and jumper them to 300rpm and double density operation.
This brings up a good point. Does anyone know FOR SURE if a 1.2meg
5-1/4" floppy drive jumpered for 300 rpm is LITERALLY interchangeable
with an 800k (80-track "quad density") drive? If this works, all I have
to do is replace my Tandon TM-100-4 with any 1.2meg drive that can be
jumpered for "low density" 300 rpm operation.
I am *NOT* talking about compatibility between a 40-track drive and the
80-track 1.2meg drive. I am talking about interchanging disks between
two 80-track drives, one "quad density" 300 rpm only, and the other a
720k/1.2meg 300/360 rpm PC-type drive.
When I tried this some years ago, I found that 80-track disks produced
by a 1.2meg drive were unreliable in my H89's 80-track Tandon TM100-4
drives. I don't know if this was due to the particular brand of drive,
disk media, software issue, etc. I just know it didn't work well enough
to trust.
My guess is that the 1.2meg drive's read/write heads and circuitry are
optimized for use with high-density disks; not the older "quad density"
disks used by the 800k drives. The 1.2meg drive will "sorta" work with
the older disks, but isn't really doing it "right", and thus produces
inferior disks that are unreliable in 80-track quad-density drives.
What do the experts think?
Randy McLaughlin
drives all use the same track width and spacing. I would have to look up
the width, but the spacing is 96 TPI (40 track uses 48 TPI).
As far as archiving goes, no magnetic storage is a good archival media. Go
to CD for true shelf life (100 years). All magnetic media suffers from bit
drift.
"Lee Hart" <leea...@earthlink.net> wrote in message
news:3C4235...@earthlink.net...
Michael C Finn
>
> "Michael C Finn" <mike...@worldnet.att.net> wrote in message
> news:sL608.82112$fe1.1...@bgtnsc06-news.ops.worldnet.att.net...
> > media but the floppy drive in your ST?
>
> Michael,
>
> The drive is a Master-5S made by Oceanic Electronics Corp. in 1988. It
was
> supposed to be new when I bought it and it looked new in the original
> packaging etc. It has a Teac FD-55GFR drive in it. There's a switch to
> select 40 or 80 track operation (360k or 720k). I don't have an Atari ST
> setup right now for testing. Most of the time formatting a disk would
fail.
> Sometimes the ST would say that the format was successful but the disk was
> always unreadable. I guess I could pop another FD-55GFR drive in it and
see
> if the original drive is bad. Atari didn't make 5-1/4 drives for the ST
so
> this was a bastard aftermarket setup. I always thought that the disks
were
> the problem. As soon as I have time I'll try another drive and see what
> happens. Thanks for the response.
Ralph,
I checked the TEAC Support WEB site at
http://www.teac.com/DSPD/support/floppy_drives/floppy_drives.htm
and that TEAC FD-55GFR floppy drive is meant to use the DSHD 1.2 meg floppy
disks. You can download a manual and view specification and jumper
information from that web site and check the jumper straps settings. The
manual will explain the default settings for an IBM compatible. The Amiga ST
and Master 5-S settings may be different as far as drive select and drive
ready signal lines, etc. Take note of how it came jumpered before making any
changes..
You can then pull that floppy drive out of the case it came in and install
it in the bay of any IBM compatible desktop and test to see if it works
under DOS/Windows using the proper IBM compatible settings. If it works on
an IBM compatible with the HD media, then you can test it out on the Amiga
ST again making any needed changes to jumper settings if the Amiga ST
requires something different than the IBM defaults.
Mike
Randy McLaughlin
"Ed" <ed...@alphalink.com.au> wrote in message
news:3c42...@news.alphalink.com.au...
>
> "Randy McLaughlin" <rand...@hotmail.com> wrote in message
> news:B0q08.23692$3x5.1...@e3500-atl2.usenetserver.com...
> > What makes an at drive a "1.2M" drive is simply the speed. 80 track
5.25
>
> I think the write current was switched as well - which probably
> explains why HD media couldn't be used on DD/QD drives (?)
>
> Ed
ae2...@wayne.edu
Epson). It worked fine with DSDD media, of all different brands. I
upgraded to a DS/DD 3.5" drive, and using all the same hardware but the
drive mechanism itself, it too worked fine. Actually, the replacement
drive could format out to 100 tracks, which the ST strangely enough could
make use of. If memory serves, the formatted capacity was close to 1 MB.
Amardeep S Chana
> Amardeep S Chana wrote:
> > If all else fails you can always get the cheap and plentiful TEAC 1.2MB
> > drives and jumper them to 300rpm and double density operation.
>
> This brings up a good point. Does anyone know FOR SURE if a 1.2meg
> 5-1/4" floppy drive jumpered for 300 rpm is LITERALLY interchangeable
> with an 800k (80-track "quad density") drive? If this works, all I have
> to do is replace my Tandon TM-100-4 with any 1.2meg drive that can be
> jumpered for "low density" 300 rpm operation.
>
For Teac 1.2MB drives the answer is yes for sure. Part of the jumpering is
to set the read/write circuitry for correct operation on 250Kbps double
density media. This includes filters and write current selection.
> I am *NOT* talking about compatibility between a 40-track drive and the
> 80-track 1.2meg drive. I am talking about interchanging disks between
> two 80-track drives, one "quad density" 300 rpm only, and the other a
> 720k/1.2meg 300/360 rpm PC-type drive.
>
> When I tried this some years ago, I found that 80-track disks produced
> by a 1.2meg drive were unreliable in my H89's 80-track Tandon TM100-4
> drives. I don't know if this was due to the particular brand of drive,
> disk media, software issue, etc. I just know it didn't work well enough
> to trust.
There could be MANY reasons why this didn't work reliably. It could have
simply been track misalignment on one of the drives or you might not have
set the write current correctly. Simply setting it to 300rpm will not
result in proper operation. The state of signal pin #2 from your controller
(if any) must be correctly matched by jumper setting to the write current
and motor rpm matrix. If your controller doesn't provide it, I believe the
drive pulls the pin up high using the terminator.
>
> My guess is that the 1.2meg drive's read/write heads and circuitry are
> optimized for use with high-density disks; not the older "quad density"
> disks used by the 800k drives. The 1.2meg drive will "sorta" work with
> the older disks, but isn't really doing it "right", and thus produces
> inferior disks that are unreliable in 80-track quad-density drives.
>
> What do the experts think?
That is a huge assumption drawn from a limited set of data. In fact, the
drives are designed to accurately read and write both types of media.
If you wish to try this in earnest, I can help you assess your application
and get the correct combination in place.
Good luck,
Amardeep
Randy McLaughlin
> AFAIK, only in a crude (hardware) way. The controller has
> only one pin available to it on the floppy interface - the
> HD/DD select pin. So all parameters that need changing when
> switching between DD and HD - rotation speed, write/erase
> current etc - would need to be done via that one pin?
The drive only needs to change rotational speed. Reduced write current,
write pre-comp, etc. is handled by the controller.
>
> "Randy McLaughlin" <rand...@hotmail.com> wrote in message
> news:EgB08.20972$V55.1...@e3500-atl1.usenetserver.com...
Axel Berger
>Write current is a controller function.
No.
Axel Berger
>What do the experts think?
I'd say they sure are interchangeable, have to be. But you are the one
who's tried it out, so in this case you are the expert and the one
whose opinion to listen to. I expect you have already considered and
hopefully ruled out the possibility of having happened on the one dud
drive?
Randy McLaughlin
"Axel Berger" <Axel_...@su2.maus.de> wrote in message
news:200201142...@su2.maus.de...
> *Randy McLaughlin* wrote on Mon, 02-01-14 14:55:
> >Write current is a controller function.
>
> No.
The reduced write signal from the controller is often called TG43 (Track
Greater than 43). All signals to the drive are TTL not analog. The signal
to write is either on, or off. There are several other TTL signals that do
the write operation including Write Gate, and TG43.
The principle is a bit like the old TTL monitors that had an extra Intensity
line to get 16 colors out (RGB = 2^3, or eight colors).
I'll dig out my old documents and look up the controller pin number for you.
Lee Hart
> AFAIK, only in a crude (hardware) way. The controller has
> only one pin available to it on the floppy interface - the
> HD/DD select pin. So all parameters that need changing when
> switching between DD and HD - rotation speed, write/erase
> current etc - would need to be done via that one pin?
As mentioned, some drives also have a TG43 signal (Track Greater than
43). But these two pins are not enough to do the whole job.
The signal coming from the read/write head is very low level, and
significantly distorted. The disk drive has a complex analog amplifier
to amplify the signal and correct for (at least some) of the time
distortion.
Since the data rate is 2:1 different for DD and HD formats, the
read/write amplifier should be changed to optimize it for each format.
To do it right, the HD/DD pin would either select between two read/write
amps, or switch component values in the one amp to optimize it for each
density. Or, they could do the el-cheapo thing and have just one amp
that is "good enough" for both formats without change. This would make
for a cheaper, but less reliable drive.
I don't know which route DD/HD drives take. Probably some of each.
And the second unknown is that I don't know if the read/write heads are
different for the DD/HD formats. If so, I'm SURE they wouldn't put two
sets of heads in a drive.
Opinions are welcome, but I'd really like to hear from someone who knows
for sure.
Don Maslin
: "Ed" <ed...@alphalink.com.au> wrote in message
: news:3c43...@news.alphalink.com.au...
:> AFAIK, only in a crude (hardware) way. The controller has
:> only one pin available to it on the floppy interface - the
:> HD/DD select pin. So all parameters that need changing when
:> switching between DD and HD - rotation speed, write/erase
:> current etc - would need to be done via that one pin?
: The drive only needs to change rotational speed. Reduced write current,
: write pre-comp, etc. is handled by the controller.
You are losing sight of the fact that many HD drives are incapable of
changing speed - or the capability is not selected - and that the
controller is then required to drop from a 500k data-rate to a 300k
data-rate to compensate for the higher rotational speed.
- don
:>
:> "Randy McLaughlin" <rand...@hotmail.com> wrote in message
:> > > > >
:> > > >
:> > > >
:> > > >
:> > >
:> > >
:> >
:> >
:> >
:>
:>
Stewart & Leta Marshall
Randy McLaughlin wrote:
> As far as archiving goes, no magnetic storage is a good archival media. Go
> to CD for true shelf life (100 years). All magnetic media suffers from bit
> drift.
I have a horror story! When my daughter went back to university after the
Christmas break, she carried her big stereo speakers up into the attic to
store them again. I found them right against a box of my 8 inch floppies for
my CompuPro. And sitting turned the worst way, back (magnet side) toward my
disks! These are large speakers, i.e. BIG magnets. Oh well. I have backups
fortunately, for most of them. But a good lesson about leaving my stuff
exposed!
cheers, Stewart
dwight elvey
> > If all else fails you can always get the cheap and plentiful TEAC 1.2MB
> > drives and jumper them to 300rpm and double density operation.
>
> This brings up a good point. Does anyone know FOR SURE if a 1.2meg
> 5-1/4" floppy drive jumpered for 300 rpm is LITERALLY interchangeable
> with an 800k (80-track "quad density") drive? If this works, all I have
> to do is replace my Tandon TM-100-4 with any 1.2meg drive that can be
> jumpered for "low density" 300 rpm operation.
>
> I am *NOT* talking about compatibility between a 40-track drive and the
> 80-track 1.2meg drive. I am talking about interchanging disks between
> two 80-track drives, one "quad density" 300 rpm only, and the other a
> 720k/1.2meg 300/360 rpm PC-type drive.
>
> When I tried this some years ago, I found that 80-track disks produced
> by a 1.2meg drive were unreliable in my H89's 80-track Tandon TM100-4
> drives. I don't know if this was due to the particular brand of drive,
> disk media, software issue, etc. I just know it didn't work well enough
> to trust.
>
> My guess is that the 1.2meg drive's read/write heads and circuitry are
> optimized for use with high-density disks; not the older "quad density"
> disks used by the 800k drives. The 1.2meg drive will "sorta" work with
> the older disks, but isn't really doing it "right", and thus produces
> inferior disks that are unreliable in 80-track quad-density drives.
>
> What do the experts think?
Hi
As far as I know, the 1.2M drives have no jumper select for
300 RPM. On a PC, when one wants to read/write a 300 RPM disk, they
simply change the controllers clock frequency and leave the
drive at 360 RPM.
I don't know of a speed select that changes the actual disk
speed. I don't recall seeing such a jumper on my drive.
Dwight
Harold F. Bower
>
> Lee Hart <leea...@earthlink.net> wrote in message news:<3C4235...@earthlink.net>...
> > Amardeep S Chana wrote:
> > > If all else fails you can always get the cheap and plentiful TEAC 1.2MB
> > > drives and jumper them to 300rpm and double density operation.
> >
> > This brings up a good point. Does anyone know FOR SURE if a 1.2meg
> > 5-1/4" floppy drive jumpered for 300 rpm is LITERALLY interchangeable
> > with an 800k (80-track "quad density") drive? If this works, all I have
> > to do is replace my Tandon TM-100-4 with any 1.2meg drive that can be
> > jumpered for "low density" 300 rpm operation.
> Hi
> As far as I know, the 1.2M drives have no jumper select for
> 300 RPM. On a PC, when one wants to read/write a 300 RPM disk, they
> simply change the controllers clock frequency and leave the
> drive at 360 RPM.
> I don't know of a speed select that changes the actual disk
> speed. I don't recall seeing such a jumper on my drive.
> Dwight
Older drives (especially TEAC which had MANY jumpers) could and often
would change the motor speed between 300 and 360 rpm depending on the
signal to Pin2. 250 kbps MFM was normally used at 300 rpm for 800 kB
80-track disks, and 500 kbps MFM at 360 rpm for 1.2 MB 'Hi-Density'
disks. Rather than changing the rotational speed which involved delays
(spinup/down time), a clock rate of 300 kbps was added (sometimes termed
'AT' controllers such as the National DP8473 and Intel 80277). If you
do the math, you will see that the density (bits per rotation) using 300
kbps at 360 rpm is the same as 250 kbps at 300 rpm resulting in
compatible disks.
To save costs, drive makers simply deleted the two-speed motor, jumpers
etc and we now have a new 'standard' :-/
Hal
Axel Berger
>Actually, the replacement drive could format out to 100 tracks, which
>the ST strangely enough could make use of.
Actually it was MSDOS that defined the header of the boot sector. All
variables, sectors per track, number of tracks, sectors per cluster and
several more are most clearly laid down. All Atari did was exactly copy
that layout - it is not their fault, that Microsoft themselves chose to
ignore and not make use of their own documented standard.
But the question here was about 5.25" and the only incompatibility I
know of (except IBMs insistence in using drive 1) is insufficient power
on the three bus signal lines I mentioned.
Axel Berger
>Reduced write current [...] is handled by the controller.
On MFM harddisks it is. Precompensation is digital, but all the analog
magnetic stuff is handled by the drive alone.
Axel Berger
>On MFM harddisks it is.
I just notice, this very probably is wrong too. Doesn't the controller
just switch an on-off line and the write current is handled by the
drive?
Axel Berger
>is often called TG43
Unless my Alzheimer has finally become obvious, that signal is not part
of *any* variation of the 34-pin bus - I might be of the 50 pin 8"
which i am not familiar with.
But even then, the current, reduced or not, is made and controlled by
the drive alone and not the controlled - that only gives a one bit
order.
Randy McLaughlin
(both 8" & 5.25") only used simple discrete components. The 5.25" drives
did not use reduced write at all, not even the early 96tpi TM100-4. The 8"
drives used the TG43 provided by the controller was added to (subtracted
from) the write data via analog electronics on the drive.
I checked and I didn't find any current floppy controller chips with the
reduced write pin anymore.
There is at least one company that provides a smart 34 pin to 50 pin
converter that seems to keep track of the track number (via a pic chip) to
apply TG43.
The old Western Digital chips (favorite S100 choice) had it, but it was only
brought out to the 50 pin connector. I'll have to dig out my Compupro
disk1a documentation to see if the 8272 (Intel/NEC/Zilog) directly supported
it like the Western Digital chip. The original IMSAI disk controller used a
parallel port to generate TG43.
I don't really know how the 3.5" drives handle reduced write, or if they
really do. I will try to see if I can find any schematics and find out. 8"
drives needed it because the relative bit speed varied so greatly from the
inner to the outer tracks. The 5.25" drives had a relatively small
difference in the length of the bit window.
"Axel Berger" <Axel_...@su2.maus.de> wrote in message
news:200201161...@su2.maus.de...
Amardeep S Chana
>
> I checked and I didn't find any current floppy controller chips with the
> reduced write pin anymore.
>
~ReduceWriteCurrent signal exists on many if not all modern PC floppy disk
interfaces at pin #2 (required to support 1.2MB drive operation). However,
it is not the same function as TG43 was. TG43 signalled the drive to change
write current based on cylinder number to compensate for bit density on the
inner tracks. The ~RWC signal on pin #2 of the 34 pin HD 5.25" drives is
used to tell the drive to switch both write current and read/write filtering
circuits to handle the two types of media these drives use (normal double
density and high density).
Some earlier AT controllers only drive this signal correctly for some of
their data rates, most notably the 300Kbps rate for double density media in
a 1.2MB drive. Thus when you connected an early model 1.4MB 3.5" drive
which operated at either 250Kbps or 500Kbps it didn't get the right signal
at pin #2 and one of the two media types would not work in that drive. To
work around this, 3.5" drive manufacturers began relying on the sensor for
the High Density hole in the disk jacket instead of the signal at pin #2.
Most 3.5" drives today are of that type.
>
> I don't really know how the 3.5" drives handle reduced write, or if they
> really do. I will try to see if I can find any schematics and find out.
8"
> drives needed it because the relative bit speed varied so greatly from the
> inner to the outer tracks. The 5.25" drives had a relatively small
> difference in the length of the bit window.
>
Neither 5.25" nor 3.5" floppy drives have ever had to change write current
based on cylinder number, only on media type.
Amardeep
Axel Berger
>I don't really know how the 3.5" drives handle reduced write,
The important point, which you did not not elaborate on, is that all
that analog magnetic stuff is totally handled by the drive alone. There
might be one bit control signal to broadly tell it what to do, but
except of that the controller controls nothing.
The only exception is precompensation, which is a subtle timing shift
to the precisely timed MFM data stream which is completely generated
and decoded by the controller alone - the part of the drive is
translation between magnetic orientation and digital level shift.
Herbert R Johnson
5.25 inch drives and media, and versus 8-inch and 3.5 inch drives. I have
recently reviewed *actual manufacturer's documents* on the drives
they produced, and I've given partial results to Lee Hart. What
I don't have are docs for 5.25 inch 1.2M drives as were typical
for IBM-type PC's. If someone has a copy of such docs, or can
refer me to a Web site where such docs can be downloaded, I'd
appreciate an email. Eventually I'll post the results here, send a
note to the CP/M FAQ, and of course place a copy on my Web site.
Also: while I have a lot of 8-inch floppy drive docs, none of
those docs seem to mention the track width or track seperation
width for 8-inch drives. That info, same terms as above, would be
appreciated.
Many regulars of comp.os.cpm know that I, as "Dr. S-100", offer an
S-100 documentation service. My site has list of S-100 documents
by manufacturer, and I offer copies for a per-page fee plus shipping
and handling. Details are on my site.
But I ALSO offer docs for various floppy drives, from 8-inch to 3.5 inch;
and some hard drives; AND a few other accessories of the 1970's and
'80's. That is how I was able to do my "research".
In general, my catchphrase is "I let the documentation do the talking".
I hope to get more docs so I can help to inform on this issue.
Herb Johnson
Herbert R. Johnson voice 609-771-1503, New Jersey USA
<a href="http://pluto.njcc.com/~hjohnson"> to my web site</a>
Web site: http://pluto.njcc.com/~hjohnson
email address: hjoh...@pluto.njcc.com
amateur astronomer and telescope tinkerer
reseller of classic Macs & accessories from Plus to PowerMac
S-100 & 8-inch drive manuals and parts, call for "Dr. S-100"
--
Herbert R. Johnson http://pluto.njcc.com/~hjohnson
hjoh...@pluto.njcc.com voice 609-771-1503, New Jersey USA
amateur astronomer and telescope tinkerer
reseller of classic Macs & accessories from Plus to PowerMac
S-100 & 8-inch drive manuals and parts, call for "Dr. S-100"
Don Maslin
: In all the chat, it's hard to glean out the technical facts about
: 5.25 inch drives and media, and versus 8-inch and 3.5 inch drives. I have
: recently reviewed *actual manufacturer's documents* on the drives
: they produced, and I've given partial results to Lee Hart. What
: I don't have are docs for 5.25 inch 1.2M drives as were typical
: for IBM-type PC's. If someone has a copy of such docs, or can
: refer me to a Web site where such docs can be downloaded, I'd
: appreciate an email. Eventually I'll post the results here, send a
: note to the CP/M FAQ, and of course place a copy on my Web site.
: Also: while I have a lot of 8-inch floppy drive docs, none of
: those docs seem to mention the track width or track seperation
: width for 8-inch drives. That info, same terms as above, would be
: appreciated.
According to the "3M Diskette Reference Manual" of 15 February 1990,
track width for 8" drives is 12 mils, and track density is 48 tpi.
This means each track occupies 20.833 mils of which the separation
must be 8.833 mils.
The corresponding figures for a 5.25" HD diskette are 6 mils, 96 tpi,
and 4.4166 mils separation.
- don
: Many regulars of comp.os.cpm know that I, as "Dr. S-100", offer an
Tilmann Reh
>
> In all the chat, it's hard to glean out the technical facts about
> 5.25 inch drives and media, and versus 8-inch and 3.5 inch drives. I have
> recently reviewed *actual manufacturer's documents* on the drives
> they produced, and I've given partial results to Lee Hart. What
> I don't have are docs for 5.25 inch 1.2M drives as were typical
> for IBM-type PC's. If someone has a copy of such docs, or can
> refer me to a Web site where such docs can be downloaded, I'd
> appreciate an email. Eventually I'll post the results here, send a
> note to the CP/M FAQ, and of course place a copy on my Web site.
I think I have a paper copy of the TEAC FD-55GV manual somewhere
at home...
Tilmann Reh
==================================================================
In a world without walls and fences, who needs Windows and Gates ?
(Sun Microsystems)
Jeff Jonas
>> them is getting progressively worse, and I would like to replace it.
>> Does anyone know of a source of 5-1/4" 80-track double-sided floppy
>> drives
Oy, I think I traded my last spares.
>Lee - Why not just replace them with 3.5" units?
I'm tempted to do what when I fire up the CP/M machines for more than
just a test, for I'm tired of handling so many different media sizes.
(my machines were all a mix of 8", 5.25" 360k, 720k).
I will keep the 8" disks and drives for archives
(particularly to keep the original distribution disks).
I have many 1.44 meg 3.5" floppy drives
and many brand-name floppies such as 3M or imation.
(all the 5.25" floppy cabinets and boxes are being reclaimed for CDs).
I even have a tin Muppets lunchbox that I intended to use for a
Z80 system just like in the Circuit Cellar project,
but back then the thin 3.5" floppy drives were out of my budget.
Lee A. Hart then replied:
> That's a good idea, and one I've considered. However, I decided not to
> make this change for a few reasons:
> 1. My concern is that the higher the density, the poorer the archival
> quality of the media.
I vaguely recall previous discussions about floppy longevity.
It was partly environmental, partly the mfgr process.
I've had floppy failures of 8", 5.25" and 3.5" disks,
but rarely on new brand name ones.
3.5 floppies have a metal hub,
don't suffer hole elongation like 5.25" or 8",
and other advantages.
> 2. The second reason is that most 3-1/2" disk drives are built like
> throwaway junk. I don't know what their long-term reliability is
> likely to be. But I do have 25-year-old 8" drives and 20-year-old
> 5-1/4" drives that are built like tanks and still work.
That's a valid point, but I have many 3.5" drives salvaged from systems,
so they're free (if you're at the right place at the right time).
I concede that they're junk: no head lift, unsure of the motor on/off
and signals since they're all crippled for the PC-AT
(different status lines, jumperable for only 2 of 4 drive select lines, etc).
> 3. The third reason is that keeping the 5-1/4" drives keeps it "stock".
> This doesn't really matter yet as my Heathkits are not considered
> collectible, but who knows! :-)
You could always put the drives back and not risk them wearing out!
--
Jeffrey Jonas
jeffj@panix(dot)com
The original Dr. JCL and Mr .hide