720k to 1.4M Question
Shawn
albeit it only has dos 3.3 and WP5.1, It has a 720k 3.5" FD and I would like
to be able to transfer files between it and my win 95 desktop. Anyone with a
Clue on how to do this please Drop me an E-mail--Thanks all
Dave
wrote:
Just put the 720k disks in the PC AFAIK
Dave
--
bma...@iglou.com
> I recently bought a Tandy 1400HD and while everything
>on it works fine; albeit it only has dos 3.3 and WP5.1, It has a
>720k 3.5" FD and I would like to be able to transfer files between
>it and my win 95 desktop. Anyone with a Clue on how to do this
>please Drop me an E-mail--Thanks all
1.4 meg disks formatted as 720k.
1.4 floppy disks have a hole in one corner which 720k disks do not have.
On most computers if you cover that hole with tape, the computer thinks it is
a 720k disk.
Net-Tamer V 1.08X - Test Drive
Rick
And again for the record, a 1.44M floppy IS NOT simply a 720k disk with an extra
hole punched in it. The magnetic media - and consequently the required write
current - is different between 720k and 1.44M disks in order to get the exta
capacity of the 1.44 disks. Trying to force a 720k drive into formatting a 1.44M
disk usually just gets you a trashed floppy with lots of bad sectors reported.
The same applies trying to force a 720k format onto a hi-density disk.
You just need to buy 720k disks which the hi-density drive on your desktop
computer can read and write to, as well as your 1400 laptop. There isn't anything
special you need to do in the 1400 to format the disks. BUT to format a 720k disk
in your desktop you need to append a switch to the command to force the drive
into low density mode: FORMAT A: /F:720 Again, once the 720k disk is properly
formatted it can be exchanged between the two computers with no problems.
Sylvan Butler
>And again for the record, a 1.44M floppy IS NOT simply a 720k disk with an extra
>hole punched in it. The magnetic media - and consequently the required write
>current - is different between 720k and 1.44M disks in order to get the exta
True.
>capacity of the 1.44 disks. Trying to force a 720k drive into formatting a 1.44M
>disk usually just gets you a trashed floppy with lots of bad sectors reported.
>The same applies trying to force a 720k format onto a hi-density disk.
Wrong. I have many (hundreds) of 720K floppies formatted as 1.4mb and a
few the other way with almost no problems. In fact, since I started
buying 1.4mb media a few years ago, I've run into a far higher
percentage of bad disks using 1.4 as 1.4 than I ever did using 720 as
1.4. I think floppy quality has gone down...
Unlike 360k and 1.2m 5.25" floppies, the DD and HD 3.5" media is very
similar. The spec of interest is the magnetic coercivity (?sp). With
5.25" media the difference between DD and HD is almost 2x. With 3.5"
media the difference is only about 30%.
>in your desktop you need to append a switch to the command to force the drive
>into low density mode: FORMAT A: /F:720 Again, once the 720k disk is properly
>formatted it can be exchanged between the two computers with no problems.
That's the safest way.
sdb
--
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"Don't Tread On Me!"
Rick
> On Wed, 26 Jul 2000 00:43:28 -0700, Rick <rick...@rcn.com> wrote:
> >And again for the record, a 1.44M floppy IS NOT simply a 720k disk with an extra
> >hole punched in it. The magnetic media - and consequently the required write
> >current - is different between 720k and 1.44M disks in order to get the exta
>
> True.
>
> >capacity of the 1.44 disks. Trying to force a 720k drive into formatting a 1.44M
> >disk usually just gets you a trashed floppy with lots of bad sectors reported.
> >The same applies trying to force a 720k format onto a hi-density disk.
>
> Wrong. I have many (hundreds) of 720K floppies formatted as 1.4mb and a
> few the other way with almost no problems. In fact, since I started
> buying 1.4mb media a few years ago, I've run into a far higher
> percentage of bad disks using 1.4 as 1.4 than I ever did using 720 as
> 1.4. I think floppy quality has gone down...
>
> Unlike 360k and 1.2m 5.25" floppies, the DD and HD 3.5" media is very
> similar. The spec of interest is the magnetic coercivity (?sp). With
> 5.25" media the difference between DD and HD is almost 2x. With 3.5"
> media the difference is only about 30%.
Not according to my references. Both 5.25 and 3.5" double density media both require
a magnetic field strength of 300 oersteds to write properly to the disk. (Quad
density is also 300 oersteds if you want to get into obscure trivia.) And in both
cases for hi-density media the spec is a magnetic field strength of 600 oersteds. I
would think that if the coercivity requirement is the same for both types of media
that the write current requirement would also be the same.
I don't know how you are getting away with it. Whenever I tried to force a 1.44M disk
into a 720k format I always get "Track 0 bad" messages. Further, even if you get it
to work you are risking data loss by forcing the drive into low write current mode
and writing a weaker signal to the media than the specs indicate is required. Might
look ok now but check the disks in a few weeks or months and see if you can still
read the entire disk without read errors.
On the other side writing to a 720k disk with a stronger write current than the media
is designed for will result in magnetic bleed through from track to track and from
flux reversal to reversal within the track. Eventually you end up with data read
errors as the high current writes begin to interact with each other.
If you ask me it's not worth the risk.
Kenneth Brody
[...writing 1.44 on 720K and vice versa, and risking data loss...]
> If you ask me it's not worth the risk.
Especially since every couple of months, the local CompUSA has 50-packs
of 1.44 floppies on sale for free-after-rebate.
As for 720's, I don't know if I've even seen them being sold for quite
some time now. (Though we have a couple of old 720K scratch disks around,
"just in case".)
--
+---------+----------------------------------+-----------------------------+
| Kenneth | kenb...@bestweb.net | "The opinions expressed |
| J. | | herein are not necessarily |
| Brody | http://www.bestweb.net/~kenbrody | those of fP Technologies." |
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Amardeep S Chana
>
>Not according to my references. Both 5.25 and 3.5" double density media
both require
>a magnetic field strength of 300 oersteds to write properly to the disk.
(Quad
>density is also 300 oersteds if you want to get into obscure trivia.) And
in both
>cases for hi-density media the spec is a magnetic field strength of 600
oersteds. I
>would think that if the coercivity requirement is the same for both types
of media
>that the write current requirement would also be the same.
Those references are not correct. First, Oersted is not a measure of
magnetic field strength but of magnetic retentivity. It describes a piece
of ferromagnetic medium's ability to retain a level of magnetization not the
field strength required to magnetize it.
The minimum Oersted ratings for common disk types are as follows:
5.25" DD media is 300 Oe.
5.25" HD media is 600 Oe.
3.5" DD media is 600 Oe.
3.5" HD media is 720 Oe.
Note that these are minimums. It is not uncommon for 720K 3.5" diskettes to
have an actual retentivity in excess of the 720 Oe minimum specified for
1.4MB.
>
>I don't know how you are getting away with it. Whenever I tried to force a
1.44M disk
>into a 720k format I always get "Track 0 bad" messages. Further, even if
you get it
>to work you are risking data loss by forcing the drive into low write
current mode
>and writing a weaker signal to the media than the specs indicate is
required. Might
>look ok now but check the disks in a few weeks or months and see if you can
still
>read the entire disk without read errors.
That "Track 0 bad" message is due to the fact that you are trying to write a
250Kbps data stream to a drive whose read/write amps are configured by the
sense hole in the diskette case to 500Kbps. It has nothing to do with the
media characteristics. If you want it to work, put a piece of sturdy opaque
material over the density hole and try it again.
Most 3.5" drives set their write current and head amp filter parameters from
the presence or absence of the density sense hole. Some drives ignore the
hole altogether and rely on the BIOS and controller to set the mode using
pin 2 in the same way it is done on 5.25" drives. One these setups, the
FORMAT command (via the BIOS function to set data rate) sets the drive
operating mode according to the format capacity, regardless of what type of
media is inserted. All IBM PS/2 models did this and some early IBM
compatibles did as well.
On these "pin 2" type drives you can certainly cross format 720K and 1.4MB
media with a very very low failure rate. I used to do this back in 1988
when the prices were significantly higher for the HD diskettes. Hundreds of
diskettes formatted and never a single bad sector. I still have some of the
diskettes and they are still readable today, some 12 years later.
>
>On the other side writing to a 720k disk with a stronger write current than
the media
>is designed for will result in magnetic bleed through from track to track
and from
>flux reversal to reversal within the track. Eventually you end up with data
read
>errors as the high current writes begin to interact with each other.
>
This is more relevant to 5.25" than 3.5". With only a 20% "minimum Oe"
rating difference between 3.5" DD and HD the danger is not statistically
significant. There is actually a larger variation over the surface of a
single piece of medium than there is in the specified rating difference
between DD and HD.
>If you ask me it's not worth the risk.
Agreed. In today's environment it isn't worth the trouble or the risk.
Amardeep
Sylvan Butler
>The minimum Oersted ratings for common disk types are as follows:
>
>5.25" DD media is 300 Oe.
>5.25" HD media is 600 Oe.
>
>3.5" DD media is 600 Oe.
>3.5" HD media is 720 Oe.
That sounds about right!
>>look ok now but check the disks in a few weeks or months and see if you can
>still
>>read the entire disk without read errors.
I've been mixing and matching 3.5 DD/HD for about 13 years now. I just
tried three of those old "720k as a 1.4mb" floppies and they are fine.
I can't find a "1.4 as a 720" right now. Those were usually done by
people with IBM PS/1 drive's that did not check for the HD indicator.
>That "Track 0 bad" message is due to the fact that you are trying to write a
>250Kbps data stream to a drive whose read/write amps are configured by the
>sense hole in the diskette case to 500Kbps. It has nothing to do with the
>media characteristics. If you want it to work, put a piece of sturdy opaque
>material over the density hole and try it again.
Yup. Works great.
>On these "pin 2" type drives you can certainly cross format 720K and 1.4MB
>media with a very very low failure rate. I used to do this back in 1988
>when the prices were significantly higher for the HD diskettes. Hundreds of
>diskettes formatted and never a single bad sector. I still have some of the
>diskettes and they are still readable today, some 12 years later.
Exactly. I was buying 100-3.5in floppies per month for me and friends,
and I bought only 720k and used them almost always as 1.4mb without
incident. When prices on 1.4mb came down (ca 1990) I bought a batch of
1.4mb and had several bad disks. I went back to 720k from MEI...
>Agreed. In today's environment it isn't worth the trouble or the risk.
Yup. I haven't seen 720k disks for years.
Tim Mann
> > similar. The spec of interest is the magnetic coercivity (?sp). With
> > 5.25" media the difference between DD and HD is almost 2x. With 3.5"
> > media the difference is only about 30%.
>
> require
> a magnetic field strength of 300 oersteds to write properly to the disk. (Quad
> density is also 300 oersteds if you want to get into obscure trivia.) And in
> both
> cases for hi-density media the spec is a magnetic field strength of 600
> oersteds.
Your references and my references seem to disagree. What are your
references?
"Upgrading & Repairing PCs Eighth Edition", chapter 13, table 13.6, available
online at http://cma.zdnet.com/book/upgraderepair/ch13/ch13.htm, says
that 5.25" DD/QD disks have a coercivity of 300 oersteads, 5.25" HD disks
have 600, 3.5" DD have 600, 3.5" HD have 720, and 3.5" ED have 750.
Tim Mann tim....@compaq.com http://www.tim-mann.org
Compaq Computer Corporation, Systems Research Center, Palo Alto, CA
Mike Webb
> Date: Mon, 24 Jul 2000 08:20:37 GMT
> >albeit it only has dos 3.3 and WP5.1, It has a 720k 3.5" FD and I would like
> >to be able to transfer files between it and my win 95 desktop. Anyone with a
> >Clue on how to do this please Drop me an E-mail--Thanks all
> Dave
Yep, a 1.44M drive will read/write/format 720K disks just fine. To format it
in a 1.44M drive you need to add a switch or two; either /f:720 or /n:9
/t:80 (either give the same results).
In fact, you can use a 1.44M drive in an older machine as a 720K drive. Since
it's plugged into a double density controller it won't operate in 1.44M mode,
but it'll run fine as a 720K drive.
I recently bought a used Compaq laptop drive (1.44M) and plan to see if I can
make it work in my Tandy 1100FD. It's got the same kind of foil ribbon cable
that the 1100FD's drive does. That is, that's what I'm going to do unless
somebody's found out where you can get BELTS for the 1100FD drive. I think
that's all that's wrong with it. Anybody found 'em?
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