Old floppy drive technical question.
Charles Sullivan
there was a specific warning that writing to a 360K diskette would
render it unreadable on a 360K drive. (The narrower write head of
the 1.2 Meg drive would leave fringes of the wider 360K track.)
A few years later, the 1.2 Meg drives then being manufactured seemed
not to have this problem. I was concurrently running two systems
for a number of years, the older of which was equipped with only 360K
drives, and I don't recollect ever having problem reading 360K diskettes
on a 360K drive which were written to with a 1990-vintage 1.2 Meg drive
(a Teac FD55GFR-142-U).
Others have mentioned that although they had write-compatibility problems
with the original IBM-AT, they too were able to read diskettes on a 360K
drive which had been written by the 1.2 Meg drive on later clone systems.
Somebody told me at the time they thought the later drives had a dual
head arrangement whereby the drive could write either the narrow track
for 1.2 Meg diskettes or a wider track for 360K diskettes. But to my
surprise the specs for this same Teac drive say that 360K is read-only -
nothing about dual heads or write compatibility.
Are there any old-timers out there who know what changes were made
to later model 1.2 Meg drives to allow write-compatibility with 360K
drives? (The tech at Teac I spoke to was too young to remember any
of this.)
Regards,
Charles Sullivan cwsu...@triad.rr.com
Artur Yelchishchev
<csul...@triad.rr.com> wrote:
>When the 1.2 Meg 5.25" floppy drive was introduced with the IBM-AT,
>there was a specific warning that writing to a 360K diskette would
>render it unreadable on a 360K drive. (The narrower write head of
>the 1.2 Meg drive would leave fringes of the wider 360K track.)
-snip-
>Somebody told me at the time they thought the later drives had a dual
>head arrangement whereby the drive could write either the narrow track
>for 1.2 Meg diskettes or a wider track for 360K diskettes.
>
>Are there any old-timers out there who know what changes were made
>to later model 1.2 Meg drives to allow write-compatibility with 360K
>drives? (The tech at Teac I spoke to was too young to remember any
>of this.)
Hello Charles,
I may be wrong, but I doubt there was any special modification;
compatibility problem was not so stright, and mostly depended from
particular drive, particular head alignment and particular media
brand/lot used.
In addition to narrow tracks, 1,2Mb media have stronger coercitivity
and smaller particle sizes in the coating, so DS/DD diskettes were
'over-magnetized' when written by HD drive. Capability to read such a
disk was unstable in different DD drives - I've seen this many times.
Interrestingly, I've encountered opposite problem once: 1,2Mb drive
refused to read old 360kb diskettes, and I had to connect my old DD
drive to read them! Later I found, that other HD drives read
'problematic' diskettes just fine.
And BTW, 1,2Mb HD drive indeed have "dual head arrangement", but not
for low-density diskettes - secondary head is used to accomplish
narrow track (by erasing its margins immediately after the track is
written by primary head)), while reading involves one head only.
Regards,
Artur Yelchishchev.
Kasey Chang
Charles Sullivan wrote:
> When the 1.2 Meg 5.25" floppy drive was introduced with the IBM-AT,
> there was a specific warning that writing to a 360K diskette would
> render it unreadable on a 360K drive. (The narrower write head of
> the 1.2 Meg drive would leave fringes of the wider 360K track.)
> A few years later, the 1.2 Meg drives then being manufactured seemed
> not to have this problem. I was concurrently running two systems
> for a number of years, the older of which was equipped with only 360K
> drives, and I don't recollect ever having problem reading 360K diskettes
> on a 360K drive which were written to with a 1990-vintage 1.2 Meg drive
> (a Teac FD55GFR-142-U).
> Others have mentioned that although they had write-compatibility problems
> with the original IBM-AT, they too were able to read diskettes on a 360K
> drive which had been written by the 1.2 Meg drive on later clone systems.
> Somebody told me at the time they thought the later drives had a dual
> head arrangement whereby the drive could write either the narrow track
> for 1.2 Meg diskettes or a wider track for 360K diskettes. But to my
> surprise the specs for this same Teac drive say that 360K is read-only -
> nothing about dual heads or write compatibility.
> Are there any old-timers out there who know what changes were made
> to later model 1.2 Meg drives to allow write-compatibility with 360K
> drives? (The tech at Teac I spoke to was too young to remember any
> of this.)
IIRC, it's the recording circuitry. The 1.2M media, in order to cram in
additional data, uses a "harder" media that needs higher gauss to actuall
record stuff onto it. Therefore the head must be 1) more precise, and 2)
generate stronger write pulses. The same head on the 360K media, without
some sort of strength adjustment, will "leak" the signal into the adjacent
tracks.
My guess is later heads can sense the 360K media and use a lower strength
recording pulse instead of the full 1.2M media pulse, though I can't
confirm that.
--address below zigzaged to foil sp...@address.com harvesters--
K C A G E C T DOT O | Kasey Chang / PC Renaissance Man
S H N AT X I E C M | Gamer / Trekker / IT Developer
If it looks too obvious, it probably is. -- anonymous
--
Posted via CNET Help.com
http://www.help.com/
Henry Broekhuyse
Ed Ngai <en...@sprintmail.com> wrote in message
news:390E5182...@sprintmail.com...
> If you have DOS 3.3 and you have (2) 1.2M fd as... A: and B: ,
> and you have some 360k double sided double density fd, then you
> type in command,
>
> c:\format a: /4 /8
>
> this will format a 360k floppy disk in a 1.2M floppy drive as
> double sided w/ 8 sectors/track. This makes no difference if
> it was a Teac, Sony, CDC, Fujitsu, Mitsubishi, etc, for any
> brand 1.2M fd.
>
> Now w/ DOs 6.22, I just formatted a 360k fd w/ the command
>
> c:\format b: /4 /8 ...and this works just fine, but you
> can't use the switch /f:360 , won't work.
>
This is true, but is peripheral to the subject of the original post. The
original post discussed what happens when (1) you take a 360K floppy
(formatted on either a 360K or 1.2M drive) that has been written to on a
360K drive, then (2) is rewritten on the same track(s) with a 1.2M drive,
and then (3) is read again on a 360K drive. At step (3) the 360K drive
should get read errors due precisely to the explanation given per the
original post:
Charles Sullivan <csul...@triad.rr.com> wrote in message
news:vvjP4.49844$O7.1...@typhoon.southeast.rr.com...
> When the 1.2 Meg 5.25" floppy drive was introduced with the IBM-AT,
> there was a specific warning that writing to a 360K diskette would
> render it unreadable on a 360K drive. (The narrower write head of
> the 1.2 Meg drive would leave fringes of the wider 360K track.)
To this day, Teac (for one) clearly states that their 1.2M drives have "read
only" backwards compatibility with 360K floppies, to prevent users from
rendering a 360K disk (formatted and previously written to on a 360K drive)
unreadable on a 360K drive.
There is one distinct situation where this is not a problem. If a brand new
(or bulk erased) 360K floppy is (1) formatted as such in a 1.2M drive and
then (2) has files written on it only by a 1.2M drive, then (3) that disk
will be perfectly readable by a 360K drive. Following Charles' explanation,
this works because all the tracks on the floppy will be "narrow" tracks
without any of the "wide" tracks (written by a 360K drive) also present but
incompletely erased to confuse the read heads of the 360K drive.
Ed Ngai
> When the 1.2 Meg 5.25" floppy drive was introduced with the IBM-AT,
> there was a specific warning that writing to a 360K diskette would
> render it unreadable on a 360K drive. (The narrower write head of
> the 1.2 Meg drive would leave fringes of the wider 360K track.)
This is wrong. I still have a 360k and 1.2M floppy drive and you
have to FORMAT the 360k in a 1.2M fd w/ the correct DOS FORMAT
command.
Ed
Charles Sullivan
news:390df8e5...@news.neti.ee...
> On Mon, 01 May 2000 17:52:27 GMT, "Charles Sullivan"
>
> >When the 1.2 Meg 5.25" floppy drive was introduced with the IBM-AT,
> >there was a specific warning that writing to a 360K diskette would
> >render it unreadable on a 360K drive. (The narrower write head of
> >the 1.2 Meg drive would leave fringes of the wider 360K track.)
> >Somebody told me at the time they thought the later drives had a dual
> >head arrangement whereby the drive could write either the narrow track
> >for 1.2 Meg diskettes or a wider track for 360K diskettes.
> >
> >to later model 1.2 Meg drives to allow write-compatibility with 360K
> >drives? (The tech at Teac I spoke to was too young to remember any
> >of this.)
>
>
> I may be wrong, but I doubt there was any special modification;
> compatibility problem was not so stright, and mostly depended from
> particular drive, particular head alignment and particular media
> brand/lot used.
>
> In addition to narrow tracks, 1,2Mb media have stronger coercitivity
> and smaller particle sizes in the coating, so DS/DD diskettes were
> 'over-magnetized' when written by HD drive. Capability to read such a
> disk was unstable in different DD drives - I've seen this many times.
>
> Interrestingly, I've encountered opposite problem once: 1,2Mb drive
> refused to read old 360kb diskettes, and I had to connect my old DD
> drive to read them! Later I found, that other HD drives read
> 'problematic' diskettes just fine.
>
> And BTW, 1,2Mb HD drive indeed have "dual head arrangement", but not
> for low-density diskettes - secondary head is used to accomplish
> narrow track (by erasing its margins immediately after the track is
> written by primary head)), while reading involves one head only.
Artur,
In that case, could the change from the IBM-AT to later 1.2 Meg
drives be to merely disable the secondary head when writing to 360K
diskettes, thus leaving a wider track?
Regards,
Charles Sullivan
Charles Sullivan
> Charles Sullivan wrote:
> > When the 1.2 Meg 5.25" floppy drive was introduced with the IBM-AT,
> > there was a specific warning that writing to a 360K diskette would
> > render it unreadable on a 360K drive. (The narrower write head of
> > the 1.2 Meg drive would leave fringes of the wider 360K track.)
>
> have to FORMAT the 360k in a 1.2M fd w/ the correct DOS FORMAT
> command.
Ed,
What is the age of your 1.2 Meg drive? My old 1.2 Meg Teac is vintage
1990. I could take a 360K diskette formatted on a 360K drive, write to
it with the 1.2 Meg drive, then satisfactorally read the diskette in a
360K drive. Others have told me they could do the same thing with
later model 1.2 Meg drives but not with the drives shipped with the
original IBM-AT. This is not something that was specified by Teac
but it did seem to work.
Regards,
Charles Sullivan
Ed Ngai
I was sysop of 'The Haunted Castle of Alchemists BBS' between
1986
to 1998, in Goleta CA, running GT Power BBS. This is a very old
thread topic.
If you have DOS 3.3 and you have (2) 1.2M fd as... A: and B: ,
and you have some 360k double sided double density fd, then you
type in command,
c:\format a: /4 /8
this will format a 360k floppy disk in a 1.2M floppy drive as
double sided w/ 8 sectors/track. This makes no difference if
it was a Teac, Sony, CDC, Fujitsu, Mitsubishi, etc, for any
brand 1.2M fd.
Now w/ DOs 6.22, I just formatted a 360k fd w/ the command
c:\format b: /4 /8 ...and this works just fine, but you
can't use the switch /f:360 , won't work.
Ed
Rez
>
> When the 1.2 Meg 5.25" floppy drive was introduced with the IBM-AT,
> there was a specific warning that writing to a 360K diskette would
> render it unreadable on a 360K drive. (The narrower write head of
> the 1.2 Meg drive would leave fringes of the wider 360K track.)
>
> not to have this problem. I was concurrently running two systems
> for a number of years, the older of which was equipped with only 360K
> drives, and I don't recollect ever having problem reading 360K diskettes
> on a 360K drive which were written to with a 1990-vintage 1.2 Meg drive
> (a Teac FD55GFR-142-U).
Contrary to all that which we've heard for years, and I know I'm going
to get a lot of "you're insane" replies for posting this, but..
I have found that the problem lies NOT in the hardware, but in DOS
FORMAT. It is NOT backward compatible. That is, a floppy formatted on a
DOS5/6 system generally cannot be read on a DOS3 system, regardless of
the hardware, but a floppy formatted on a DOS3 system can always be read
on a DOS5/6 system (5 and 6 have the same boot sector ID) again
regardless of the hardware, or even on the SAME hardware that when
booted with DOS3, had just refused to read a DOS5/6-formatted disk.
Apparently the differences in the boot sector make DOS5/6 floppies
unreadable to DOS3.x.
I experimented with M$DOS 3.2, 3.3, 5.0, 6.0, and 360k and 1.2mb drives
of various eras, and the results always depended on the OSs that
formatted the disk vs the OS trying to read the disk, never on the
hardware. At the time I even had some of the ancient black-faced 360k
drives with snap-down doors, and they had no problem at all reading
disks formatted on 1.2mb drives of vintages friom 1988-1994, provided
the DOS used to boot the system was the same or later than the DOS used
to format the floppy. But reboot with DOS3, and all of a sudden they
couldn't read the DOS5/6-formatted floppies.
Note: DRDOS uses a boot sector ID of DOS 3.something, and its disks
behaved accordingly.
~REZ~
Rez
> I was sysop of 'The Haunted Castle of Alchemists BBS' between
> 1986
> to 1998, in Goleta CA, running GT Power BBS. This is a very old
> thread topic.
We still run a BBS in Granada Hills. :)
> If you have DOS 3.3 and you have (2) 1.2M fd as... A: and B: ,
> and you have some 360k double sided double density fd, then you
> type in command,
>
> c:\format a: /4 /8
>
> this will format a 360k floppy disk in a 1.2M floppy drive as
> double sided w/ 8 sectors/track. This makes no difference if
> it was a Teac, Sony, CDC, Fujitsu, Mitsubishi, etc, for any
> brand 1.2M fd.
>
> Now w/ DOs 6.22, I just formatted a 360k fd w/ the command
>
> c:\format b: /4 /8 ...and this works just fine, but you
> can't use the switch /f:360 , won't work.
The /f:360 switch works just fine for me. Or do you mean it writes a
disk that the old drive can't read? I never found that to be true. I
never used the /4 /8 switches, only the /f:360 switch, when doing my
extensive test formattings (see othre message). Only thing that ever
made a bit of difference was the DOS version.
~REZ~
Tom Lavedas
>
> When the 1.2 Meg 5.25" floppy drive was introduced with the IBM-AT,
> there was a specific warning that writing to a 360K diskette would
> render it unreadable on a 360K drive. (The narrower write head of
> the 1.2 Meg drive would leave fringes of the wider 360K track.)
>
> A few years later, the 1.2 Meg drives then being manufactured seemed
> not to have this problem. I was concurrently running two systems
> for a number of years, the older of which was equipped with only 360K
> drives, and I don't recollect ever having problem reading 360K
> diskettes on a 360K drive which were written to with a 1990-vintage
> 1.2 Meg drive (a Teac FD55GFR-142-U).
>
> problems with the original IBM-AT, they too were able to read
> on later clone systems.
>
> head arrangement whereby the drive could write either the narrow
> read-only - nothing about dual heads or write compatibility.
>
> to later model 1.2 Meg drives to allow write-compatibility with 360K
> drives? (The tech at Teac I spoke to was too young to remember any
> of this.)
>
> Charles Sullivan cwsu...@triad.rr.com
It is my understanding that the problem with writing 360's on the first
1.2's was, as stated by you and others, the width of the track laid down
by the narrower head of the 1.2's. However, I have seen no one give
what I believe is the correct explanation of how the later drives were
modified to get around this problem.
As I remember, the drives were modified to lay down FOUR IDENTICAL BITS
in a row when writing 360's. This approximated the width of the bits on
the lower density media. That made it reasonably likely the older
drives could read the disks written by the newer ones. As far as I
recall it was never a problem of reading 360's on 1.2's, just the other
way around. However, I also remember that there were also a lot of
disclaimers made at the same time as the changes were instituted. My
read was that all of this was coming from the lawyers and not from the
engineers involved. IBM was getting a lot of heat for the original
problems with the 1.2's and wanted to keep from getting into more over
their proffered fix.
At least, that's what I remember.
Tom Lavedas
-----------
http://www.pressroom.com/~tglbatch/
Artur Yelchishchev
Hmm, maybe! In fact, I don't remember precisely, but if I'm correct,
the change in writing was purely in logical format, not current level
or so, bubt I'll have to re-read my old books about this. Your idea
looks reasnonably - if only FDD controller is smart enough to swith
something depending from tracks/sectors requested by host.
If I'm right, Low Density/High Density signal line works only with 3
inch drives (where, in many drives, it actually changes writing
parameters and is also reported to the host), and in five-inch drives
there was no way to 'detect' actual media, so it relay on what you've
told him.
Artur.
Henry Broekhuyse
> If I'm right, Low Density/High Density signal line works only with 3
> inch drives (where, in many drives, it actually changes writing
> parameters and is also reported to the host), and in five-inch drives
> there was no way to 'detect' actual media, so it relay on what you've
> told him.
Signal line "2" is an input to a 1.2M 5.25" drive from the controller, and
it determines whether the drive should be in standard or high density mode.
Charles Sullivan
> Charles Sullivan wrote:
>
> > Ed Ngai <en...@sprintmail.com> wrote in message
> > news:390E210F...@sprintmail.com...
>
> > > > When the 1.2 Meg 5.25" floppy drive was introduced with the IBM-AT,
> > > > there was a specific warning that writing to a 360K diskette would
> > > > render it unreadable on a 360K drive. (The narrower write head of
> > > > the 1.2 Meg drive would leave fringes of the wider 360K track.)
>
> > > have to FORMAT the 360k in a 1.2M fd w/ the correct DOS FORMAT
> > > command.
>
> > Ed,
> > What is the age of your 1.2 Meg drive? My old 1.2 Meg Teac is vintage
> > 1990. I could take a 360K diskette formatted on a 360K drive, write to
> > it with the 1.2 Meg drive, then satisfactorally read the diskette in a
> > 360K drive. Others have told me they could do the same thing with
> > later model 1.2 Meg drives but not with the drives shipped with the
> > original IBM-AT. This is not something that was specified by Teac
> > but it did seem to work.
>
> 1986
> to 1998, in Goleta CA, running GT Power BBS. This is a very old
> thread topic.
>
> and you have some 360k double sided double density fd, then you
> type in command,
>
> c:\format a: /4 /8
>
> this will format a 360k floppy disk in a 1.2M floppy drive as
> double sided w/ 8 sectors/track. This makes no difference if
> it was a Teac, Sony, CDC, Fujitsu, Mitsubishi, etc, for any
> brand 1.2M fd.
>
> Now w/ DOs 6.22, I just formatted a 360k fd w/ the command
>
> c:\format b: /4 /8 ...and this works just fine, but you
> can't use the switch /f:360 , won't work.
8 sectors per track yields only a 320K floppy (8*40*2*512/1024=320).
All you need for a 360K diskette in a 1.2M drive is the /4 switch.
If you format a totally blank, never before formatted, diskette in
a 1.2M drive, I wouldn't expect any problem reading it in a 360K
drive. It's only when the diskette has been formatted in a true
360K drive with its wider track, then written on with one of the
original IBM-AT 1.2M drives, that there was a problem in subsequently
reading the disk back on the 360K drive.
Regards,
Charles Sullivan
Charles Sullivan
news:390EE412...@pressroom.com...
> Charles Sullivan wrote:
> >
> > When the 1.2 Meg 5.25" floppy drive was introduced with the IBM-AT,
> > there was a specific warning that writing to a 360K diskette would
> > render it unreadable on a 360K drive. (The narrower write head of
> > the 1.2 Meg drive would leave fringes of the wider 360K track.)
> >
That sounds similar to what I heard, but writing 4 bits in parallel
would require 4 heads, which seems overmuch. Having a second head
which would write a track 4 times as wide would seem to suffice.
You're probably right about the lawyers; the specs for my 1990-vintage
Teac say that 360K diskettes are read-only, but I never remember having
any trouble reading them on a 360K drive after they had been written
on this Teac 1.2M drive. (The diskettes were almost always formatted
on a 360K drive.)
Regards,
Charles Sullivan
Ed Ngai
en...@sprintmail.com wrote:
> > c:\format b: /4 /8 ...and this works just fine, but you
> > can't use the switch /f:360 , won't work.
> The /f:360 switch works just fine for me. Or do you mean it writes a
> disk that the old drive can't read? I never found that to be true. I
> never used the /4 /8 switches, only the /f:360 switch, when doing my
> extensive test formattings (see othre message). Only thing that ever
> made a bit of difference was the DOS version.
I'm using MSDOS 6.22 on 1 pc and it wont except the f:/360
switch.
Who knows ?
Ed
SeanB51229
> I'm using MSDOS 6.22 on 1 pc and it wont except
> the f:/360 switch.
Try /f:360 instead. It works on my MS-DOS 6.20
machine.
Sean Bernard
SeanB...@aol.com
Artur Yelchishchev
<lav...@pressroom.com> wrote:
>As I remember, the drives were modified to lay down FOUR IDENTICAL BITS
>in a row when writing 360's. This approximated the width of the bits on
>the lower density media.
Hello Tom,
What 'row' are you referring to? Head/media movement is purely
circular during read/write process, and head physically can not make
radial move other than positioning, I believe? Do you mean each track
is written four times with small shift?
>As far as I
>recall it was never a problem of reading 360's on 1.2's, just the other
>way around.
How about my personal experience then? :-)
Regards,
Artur.
Artur Yelchishchev
Isn't it the same as what I've said? :-)
Artur.
Tom Lavedas
>
> Tom Lavedas <lav...@pressroom.com> wrote in message
> news:390EE412...@pressroom.com...
> > Charles Sullivan wrote:
> > >
> > > When the 1.2 Meg 5.25" floppy drive was introduced with the
> > > IBM-AT, there was a specific warning that writing to a 360K
> > > diskette would render it unreadable on a 360K drive. (The
> > > narrower write head of the 1.2 Meg drive would leave fringes of
> > > the wider 360K track.)
> > >
> > > A few years later, the 1.2 Meg drives then being manufactured
> > > seemed not to have this problem. I was concurrently running two
> > > systems for a number of years, the older of which was equipped
> > > with only 360K drives, and I don't recollect ever having problem
> > > reading 360K diskettes on a 360K drive which were written to with
> > > a 1990-vintage 1.2 Meg drive (a Teac FD55GFR-142-U).
> > >
> > > Others have mentioned that although they had write-compatibility
> > > problems with the original IBM-AT, they too were able to read
> > > diskettes on a 360K drive which had been written by the 1.2 Meg
> > > drive on later clone systems.
> > >
> > > Somebody told me at the time they thought the later drives had a
> > > say that 360K is read-only - nothing about dual heads or write
> > > compatibility.
> > >
> > > Are there any old-timers out there who know what changes were
> > > made to later model 1.2 Meg drives to allow write-compatibility
> > > with 360K drives? (The tech at Teac I spoke to was too young to
> > > remember any of this.)
> > >
> > > Regards,
> > > Charles Sullivan cwsu...@triad.rr.com
> >
> > It is my understanding that the problem with writing 360's on the
> > first 1.2's was, as stated by you and others, the width of the
> > track laid down by the narrower head of the 1.2's. However, I have
> > seen no one give what I believe is the correct explanation of how
> > the later drives were modified to get around this problem.
> >
> > BITS in a row when writing 360's. This approximated the width of
> > on 1.2's, just the other way around. However, I also remember that
> > changes were instituted. My read was that all of this was coming
> > from the lawyers and not from the engineers involved. IBM was
> > getting a lot of heat for the original problems with the 1.2's and
> > wanted to keep from getting into more over their proffered fix.
> >
> > At least, that's what I remember.
>
> That sounds similar to what I heard, but writing 4 bits in parallel
> would require 4 heads, which seems overmuch. Having a second head
> which would write a track 4 times as wide would seem to suffice.
>
> You're probably right about the lawyers; the specs for my
> 1990-vintage Teac say that 360K diskettes are read-only, but I never
> remember having any trouble reading them on a 360K drive after they
> had been written on this Teac 1.2M drive. (The diskettes were almost
> always formatted on a 360K drive.)
>
> Regards,
> Charles Sullivan
I didn't mean in parallel. I understood it was in series. That is,
with NO extra heads. Just the narrow one that was standard - all done
with firmware. That was the beauty (and shortcoming) of the solution.
As I understand it, the only thing that changed was the azmuthal width
of the heads (just two - top and bottom) and the rate at which the data
was written. According to my DOS 5.0 manual, both the 360 KB and 1.2 MB
drives have 80 tracks (radial direction), so the only parameters that
changed were the number of sectors and the number of bits per sector -
both angularly related parameters. Therefore, the difference was in the
angular width of the bits - four times as many for 1.2 MB than for 360
KB.
Tom Lavedas
>
> On Tue, 02 May 2000 10:20:02 -0400, Tom Lavedas
> <lav...@pressroom.com> wrote:
>
> >BITS in a row when writing 360's. This approximated the width of the
> >bits on the lower density media.
>
>
> What 'row' are you referring to? Head/media movement is purely
> circular during read/write process, and head physically can not make
> radial move other than positioning, I believe? Do you mean each track
> is written four times with small shift?
The data is laid down four times as dense in the anglular
(circumferential) direction on a 1.2, so to simulate the 360 data, four
identical bits can be written, one after the other. The wider head on
the 360 averaged these to gether, but with grater accuracy than for the
one narrow bit that was laid down by the original drives.
> >As far as I recall it was never a problem of reading 360's on 1.2's,
> >just the other way around.
>
> How about my personal experience then? :-)
>
> Regards,
> Artur.
Well, as I said, "That made it reasonably likely the older drives could
read the disks written by the newer ones." It still depended upon good
head alignment and other calibration issues. It might also have had
something to do with the 'quality' of the magnetic media as well, as
alluded to in anther post in this thread. Heck, I have trouble today
passing data between so called compatible 1.44 MD drives.
Henry Broekhuyse
> with NO extra heads. Just the narrow one that was standard - all done
> with firmware. That was the beauty (and shortcoming) of the solution.
If I am following this correctly, are you suggesting that writing several
identical flux transitions (in series) to the media on a 1.2Meg drive would
(presumably) appear as one "big" flux transition on a 360K drive (keeping in
mind the principle of MFM encoding of data on a floppy, where individual
bits are not stored as such).
Charles Sullivan
> > > BITS in a row when writing 360's. This approximated the width of
> > > likely the older drives could read the disks written by the newer
> > > on 1.2's, just the other way around. However, I also remember that
> > > there were also a lot of disclaimers made at the same time as the
> > > changes were instituted. My read was that all of this was coming
> > > from the lawyers and not from the engineers involved. IBM was
> > > getting a lot of heat for the original problems with the 1.2's and
> > > wanted to keep from getting into more over their proffered fix.
> > >
> > > At least, that's what I remember.
> >
> > That sounds similar to what I heard, but writing 4 bits in parallel
> > would require 4 heads, which seems overmuch. Having a second head
> > which would write a track 4 times as wide would seem to suffice.
> >
> > You're probably right about the lawyers; the specs for my
> > 1990-vintage Teac say that 360K diskettes are read-only, but I never
> > remember having any trouble reading them on a 360K drive after they
> > had been written on this Teac 1.2M drive. (The diskettes were almost
> > always formatted on a 360K drive.)
> >
> > Regards,
> > Charles Sullivan
>
> with NO extra heads. Just the narrow one that was standard - all done
> with firmware. That was the beauty (and shortcoming) of the solution.
>
> of the heads (just two - top and bottom) and the rate at which the data
> was written. According to my DOS 5.0 manual, both the 360 KB and 1.2 MB
> drives have 80 tracks (radial direction), so the only parameters that
> changed were the number of sectors and the number of bits per sector -
> both angularly related parameters. Therefore, the difference was in the
> angular width of the bits - four times as many for 1.2 MB than for 360
> KB.
The old 360K drives only stepped 40 tracks. For this format there are
9 sectors/track * 40 tracks * 2 sides * 512 bytes/sector / 1024 bytes/Kbyte
= 360Kbytes. A 1.2 Meg drive is stepped twice to move between tracks when
handling 360K diskettes.
For the 1.2 Meg format there are 15 sectors/track * 80 tracks * 2 sides
* 512 bytes/sector / 1024 bytes/Kbyte = 1200Kbytes = 1.2 Meg.
The azimuthal (tangential) width of the individual bits is I think
determined by the data rate, which is proportionately slower for 360K
writes. The old 360K drives also ran slower - 300 rpm vs 360 rpm for the
1.2 Meg drives. (Teac 1.2 Meg drives can be operated in dual-speed
mode where the drive slows down when handling 360K diskettes and the
data rate is adjusted accordingly. The default jumpering is to operate
at the same speed for both 1.2 Meg and 360K.)
But none of this explains how the radial width of the track written by
a 1.2 Meg drive is increased for compatibility with old 360K drives.
In the absence of multiple heads, the only thing I can think of is
control of the write current - more current with the same media would
tend to smear out the magnetized area.
Regards,
Charles Sullivan
Henry Broekhuyse
Charles Sullivan <csul...@triad.rr.com> wrote in message news:4e6Q4.81294
> But none of this explains how the radial width of the track written by
> a 1.2 Meg drive is increased for compatibility with old 360K drives.
> In the absence of multiple heads, the only thing I can think of is
> control of the write current - more current with the same media would
> tend to smear out the magnetized area.
Perhaps, but the tunnel erase head which follows the read/write head would
(and is designed) to remove the "smear". Artur Yelchishchev's first response
to your query makes the most sense - perhaps the tunnel erase head is
"turned off" when the disk is written in DD mode on a HD drive and the
normally produced "smear" is left in place.
However (again echoing Artur's comments) it is more likely that no specific
engineering changes were made. The observed success in reading 360K disks
(on a 360K drive) when previously written to on a 1.2M drive may be entirely
due sufficient leeway in design tolerances so that sometimes you can get
away with it. Current Teac 1.2M drives are still rated as "read only" for
360K disks - implying that doing so is neither recommended nor supported.
This being the case, it is doubtful they made any engineering changes
towards a solution.
Artur Yelchishchev
<csul...@triad.rr.com> wrote:
>But none of this explains how the radial width of the track written by
>a 1.2 Meg drive is increased for compatibility with old 360K drives.
>In the absence of multiple heads, the only thing I can think of is
>control of the write current - more current with the same media would
>tend to smear out the magnetized area.
I think the same - but it seems to be 'non-standard' and depends from
internal floppy circuit's design; one of my books notes signal pin 2
of floppy interface as "High Density/Low Density", while in other this
very pin called "Reduce Write (Low Current)". It makes me thinking it
is _not_ DD/HD selection signal (it was present in "pure" 360kb
drives, too), but just related to the linear density change between
inner and outer tracks - similar to antique MFM (ST-506) hard disk's
"Write Precompensation" field (anyone remember it? :-))
BTW, third book say pin 4 is "Head Load" (while two previous call it
'reserved'), and I even have 5" drive where head assembly is driven by
electromagnet and actually pulled out when read/write operations end
up, but spindle still rotating yet (although this circuit is
controlled by Drive Select/Motor On signal AFAIK). Almost as good done
as 8" floppy was!
WBR,
Artur.
Henry Broekhuyse
> internal floppy circuit's design; one of my books notes signal pin 2
> of floppy interface as "High Density/Low Density", while in other this
> very pin called "Reduce Write (Low Current)". It makes me thinking it
> is _not_ DD/HD selection signal (it was present in "pure" 360kb
> drives, too), but just related to the linear density change between
> inner and outer tracks - similar to antique MFM (ST-506) hard disk's
> "Write Precompensation" field (anyone remember it? :-))
Pin 2 was not used on any 5.25" floppy drives (prior to the HD models) that
were used with the IBM-PC, since "write precompensation" was unnecessary on
their 360K drives. I do not know for certain if this pin was ever used by
any 5.25" drives before the PC "standard".
The definition "reduced write current" is an anachronism to the days when it
was used for this very purpose on the 50-pin 8" drive interface (where it
also happened to be pin 2). It was a signal from the controller which was
activated when writing to tracks 43-77 on an 8" drive, and told the drive to
reduce the write current when writing to these (inner) disk tracks. As you
said, its' purpose was equivalent to the old ST-506-compatible hard drive's
"write precomp" interface signal (yes, I remember them and still have
several running in pre-PC computer systems).
As you discovered, the current definition of this pin varies depending on
the book you read but its function is always the same on 1.2Meg drives - it
signals the drive to increase the head current when writing to high-density
floppies, since "high density" media requires a higher field strength for
writing on all tracks. Could (as some have suggested in this discussion)
this function also be used to improve compatibility when writing to 360K
disks - doubtful. Que's book "Upgrading and Repairing PCs" specifically
warns against doing the equivalent, which is attempting to format a non-HD
disk as 1.2Meg (their rationale, among others - the more strongly recorded
signal cannot be reliably overwritten again by the lower write current of
the 360K drive, rendering the disk useless for writing on 360K drives until
it is bulk erased).
> BTW, third book say pin 4 is "Head Load" (while two previous call it
> 'reserved'), and I even have 5" drive where head assembly is driven by
> electromagnet and actually pulled out when read/write operations end
> up, but spindle still rotating yet (although this circuit is
> controlled by Drive Select/Motor On signal AFAIK). Almost as good done
> as 8" floppy was!
Ah, someone else who has seen these "antiques" :)
There were some (non-PC) systems of the era with controllers that did drive
the "head load", "drive select" and "motor on" lines independently on 5.25"
drives with a head assembly as you described, just like their 8"
predecessors. It was a good thing when that design was abandoned (noisy!).
Pin 4 ("head load", also sometimes called "in use") was never used with the
IBM-PC's 360K drive controller or its successors, but interestingly Teac
drives (at least, up until a few short years ago) still supported this line
as an input even though the electro-mechanical head load assembly had long
since been abandoned.
- Henry
Artur Yelchishchev
<bro...@unixg.ubc.ca> wrote:
>Pin 2 was not used on any 5.25" floppy drives (prior to the HD models) that
>were used with the IBM-PC, since "write precompensation" was unnecessary on
>their 360K drives. I do not know for certain if this pin was ever used by
>any 5.25" drives before the PC "standard".
Hmm, one day I'll check what's actually going on pin 2 (using both
kinds of diskettes) with oscilloscope! My very old WD1003 card
documentation says pin 2 is 'Reduced Write', pin 4 'Reserved' and pin
6 - 'Drive Select 3'; while docs for relatively new 'Hexa I/O Plus
card' by Datatech Enterprises Co., Ltd. notes all of them (2,4, and 6)
as 'Unused' - and this card is designed for PC/AT and 386 - i.e.,
definitely for HD drives, too...
>The definition "reduced write current" is an anachronism to the days when it
>was used for this very purpose on the 50-pin 8" drive interface (where it
>also happened to be pin 2). It was a signal from the controller which was
>activated when writing to tracks 43-77 on an 8" drive, and told the drive to
>reduce the write current when writing to these (inner) disk tracks.
Well, I see you've worked with those drives! I've used to use them,
too - but at that time I had really basic knowledge about computers
and only can recall the machines were running some kind of CP/M system
and CPU was some Soviet Z-80 clone.
Do you remember what capacity/configuration 8" floppy has? I think
we've had both one- and double-sided models, but I know nothing about
logical structure.
>its' purpose was equivalent to the old ST-506-compatible hard drive's
>"write precomp" interface signal (yes, I remember them and still have
>several running in pre-PC computer systems).
Very first HDD I've seen in personal computers (not including big
machines here) was Commodore's MFM drive, something from CPC, IIRC.
Later, in AT clones I frequently saw Seagate and NEC drives of 20 and
40Mb size. Currently I have some of them spinning in 286 used for
nostalgic purposes - no problem reading the data!
>As you discovered, the current definition of this pin varies depending on
>the book you read but its function is always the same on 1.2Meg drives - it
>signals the drive to increase the head current when writing to high-density
>floppies,
So, it must be controlled by DOS Format command? 5" disks can not be
mechanically identified, so only way for FDC to decide whether to
switch this signal on is to analize sectors/tracks value requested by
host?
>since "high density" media requires a higher field strength for
>writing on all tracks. Could (as some have suggested in this discussion)
>this function also be used to improve compatibility when writing to 360K
>disks - doubtful. Que's book "Upgrading and Repairing PCs" specifically
>warns against doing the equivalent, which is attempting to format a non-HD
>disk as 1.2Meg (their rationale, among others - the more strongly recorded
>signal cannot be reliably overwritten again by the lower write current of
>the 360K drive, rendering the disk useless for writing on 360K drives until
>it is bulk erased).
There is one more limitation beyond media coercitivity - 1,2Mb media
designed to write sectors more compact than 360kb (15 vs 9), and we've
all the time successfully used DD diskettes formatted in HD drive
using 800.com utility (i.e., the same 80 narrow tracks and strong
magnetic field as in HD media) - no single problem in reliability nor
interchange between other machines. Attempts to format them as HD
result in ~50% bad sectors and total useless...
>> Almost as good done
>> as 8" floppy was!
>Ah, someone else who has seen these "antiques" :)
>There were some (non-PC) systems of the era with controllers that did drive
>the "head load", "drive select" and "motor on" lines independently on 5.25"
>drives with a head assembly as you described, just like their 8"
>predecessors. It was a good thing when that design was abandoned (noisy!).
In fact, it was very useful in 8" drives - spindle was driven via belt
by constantly rotating AC motor, and the heads and media were at risk
of heavy wear.
>Pin 4 ("head load", also sometimes called "in use") was never used with the
>IBM-PC's 360K drive controller or its successors, but interestingly Teac
>drives (at least, up until a few short years ago) still supported this line
>as an input even though the electro-mechanical head load assembly had long
>since been abandoned.
I think, for 5" where DC motor can be stopped/started quickly enough,
'Head Load' electromechanical assembly have only one feature -
decrease access time to the less possible value, but it probably
require appropriate DIP-switch settings and non-standard FDC. As I
said, in my case this mechanism _is_ working, but motor is powered up
only when disk is accessed, as in all common drives.
Anyone here may post URL for SA-400 standard interface documentation
and detailed signal descriptions?
Regards,
Artur.
Henry Broekhuyse
> Hmm, one day I'll check what's actually going on pin 2 (using both
> kinds of diskettes) with oscilloscope! My very old WD1003 card
> documentation says pin 2 is 'Reduced Write', pin 4 'Reserved' and pin
> 6 - 'Drive Select 3'; while docs for relatively new 'Hexa I/O Plus
> card' by Datatech Enterprises Co., Ltd. notes all of them (2,4, and 6)
> as 'Unused' - and this card is designed for PC/AT and 386 - i.e.,
> definitely for HD drives, too...
Up until the arrival of floppy controllers for 5.25" high density drives pin
2 had no functional use on PCs and (at least on IBM's own controller board)
was unused. The "reduced write current signal" was still produced by the
NEC 765/Intel 8272 controller chips - I suspect that some manufacturers of
controller boards based on these chips (or their functional clones) still
brought out this signal to pin 2 for "completeness" rather than any actually
need since this signal was generated by the controller chip itself and only
made sense in the context of controlling an 8" drive. It was nice to have
that signal present for those hardy individuals who wanted to hook up an 8"
drive to a PC (not that difficult, actually).
> Do you remember what capacity/configuration 8" floppy has? I think
> we've had both one- and double-sided models, but I know nothing about
> logical structure.
The standard SSSD format was 128 bytes/sector x 26 sectors x 77 tracks =
256K bytes
A DSDD disk could be formatted to hold up to 1.2Meg.
> >As you discovered, the current definition of this pin varies depending on
> >the book you read but its function is always the same on 1.2Meg drives -
it
> >signals the drive to increase the head current when writing to
high-density
> >floppies,
>
> So, it must be controlled by DOS Format command? 5" disks can not be
> mechanically identified, so only way for FDC to decide whether to
> switch this signal on is to analize sectors/tracks value requested by
> host?
Correct.
> There is one more limitation beyond media coercitivity - 1,2Mb media
> designed to write sectors more compact than 360kb (15 vs 9), and we've
> all the time successfully used DD diskettes formatted in HD drive
> using 800.com utility (i.e., the same 80 narrow tracks and strong
> magnetic field as in HD media) - no single problem in reliability nor
> interchange between other machines. Attempts to format them as HD
> result in ~50% bad sectors and total useless...
No. What the 800.com utility is doing is formatting the disk in standard
double density (not high density) format, and using all 80 tracks of the
floppy available to the newer 1.2Meg drives, to give you an 800K (roughly)
disk. Back in the old days you could actually buy what was called a "quad
density" drive, which was standard DSDD but had double the number of tracks
of the double density drives just like the "modern" 1.2Meg drives. These
drives were never standard on any PCs that I know of. 800.com is simply
emulating the function of those drives.
> In fact, it was very useful in 8" drives - spindle was driven via belt
> by constantly rotating AC motor, and the heads and media were at risk
> of heavy wear.
Quite right!
> I think, for 5" where DC motor can be stopped/started quickly enough,
> 'Head Load' electromechanical assembly have only one feature -
> decrease access time to the less possible value, but it probably
> require appropriate DIP-switch settings and non-standard FDC. As I
> said, in my case this mechanism _is_ working, but motor is powered up
> only when disk is accessed, as in all common drives.
Usually, on the drives with a head load mechanism, there was a way to
jumper-configure the drive so that the head loaded on some combination of
"drive select" and "motor on". I have seen these drives used on old PCs with
a standard floppy controller which didn't drive the "head load" signal line.
> Anyone here may post URL for SA-400 standard interface documentation
> and detailed signal descriptions?
1-33 ground
2 unused (on most PC and non-PC controllers)
4 head load
6 drive select 3
8 index
10 drive select 0
12 drive select 1
14 drive select 2
16 motor on
18 direction
20 step
22 write data
24 write enable
26 track 0
28 write protect
30 read data
32 select head 1
34 ready
The original PC controller departed from this standard in the use of the
drive select and motor on lines (remember the twisty-cable workaround). It
did not make use of lines 2,4, 6 and 34 (ref. the IBM PC Technical Reference
Manual).
- Henry
Joe Schlatter
(Snipped a lot of interesting stuff:)
>(The tech at Teac I spoke to was too young to remember any
>of this.)
You should try taking an old VW Beetle into a present day VW dealer. I do
all the work on my Beetle, but, sometimes just to stir things up, I go into
the local dealership and ask for some parts or service. Freaks them out.
>
>Regards,
>Charles Sullivan cwsu...@triad.rr.com
>
>
>
Artur Yelchishchev
<bro...@unixg.ubc.ca> wrote:
>Up until the arrival of floppy controllers for 5.25" high density drives pin
>2 had no functional use on PCs and (at least on IBM's own controller board)
>was unused. The "reduced write current signal" was still produced by the
>NEC 765/Intel 8272 controller chips - I suspect that some manufacturers of
>controller boards based on these chips (or their functional clones) still
>brought out this signal to pin 2 for "completeness" rather than any actually
>need since this signal was generated by the controller chip itself and only
>made sense in the context of controlling an 8" drive. It was nice to have
>that signal present for those hardy individuals who wanted to hook up an 8"
>drive to a PC (not that difficult, actually).
I doubt this signal is still provided for almost irreal "compatibility
purposes" only - even address space for third & fourth floppy drives
was removed (registers for C & D floppy are 'reserved' or 'unused' by
now)...
>The standard SSSD format was 128 bytes/sector x 26 sectors x 77 tracks =
>256K bytes
>A DSDD disk could be formatted to hold up to 1.2Meg.
Thanks!
>> There is one more limitation beyond media coercitivity - 1,2Mb media
>> designed to write sectors more compact than 360kb (15 vs 9), and we've
>> all the time successfully used DD diskettes formatted in HD drive
>> using 800.com utility (i.e., the same 80 narrow tracks and strong
>> magnetic field as in HD media) - no single problem in reliability nor
>> interchange between other machines. Attempts to format them as HD
>> result in ~50% bad sectors and total useless...
>No.
?!? "No" what?
>What the 800.com utility is doing is formatting the disk in standard
>double density (not high density) format, and using all 80 tracks of the
>floppy available to the newer 1.2Meg drives, to give you an 800K (roughly)
>disk. Back in the old days you could actually buy what was called a "quad
>density" drive, which was standard DSDD but had double the number of tracks
>of the double density drives just like the "modern" 1.2Meg drives. These
>drives were never standard on any PCs that I know of. 800.com is simply
>emulating the function of those drives.
Absolutely agree with you, but still don't understand if there is any
contradiction with my previous statement! :-) As I said, more tracks
and stronger magnetic field in HD drives were not obstacle to use DD
diskettes, and really impossible was only achieve 15 spt on them.
>Usually, on the drives with a head load mechanism, there was a way to
>jumper-configure the drive so that the head loaded on some combination of
>"drive select" and "motor on". I have seen these drives used on old PCs with
>a standard floppy controller which didn't drive the "head load" signal line.
Like it does in my PC currently.
>> Anyone here may post URL for SA-400 standard interface documentation
>> and detailed signal descriptions?
>
>1-33 ground
>2 unused (on most PC and non-PC controllers)
>4 head load
Thanks, but I meant full ANSI or IEEE standard white papers (as
they're available for SCSI or ATA specifications).
Funny but I can't find any web page with 'official' source!
>The original PC controller departed from this standard in the use of the
>drive select and motor on lines (remember the twisty-cable workaround). It
>did not make use of lines 2,4, 6 and 34 (ref. the IBM PC Technical Reference
>Manual).
AFAIK, pin 34 was returned to use under 'Disk Change' name.
WBR,
Artur.
Henry Broekhuyse
"compatibility
> purposes" only - even address space for third & fourth floppy drives
> was removed (registers for C & D floppy are 'reserved' or 'unused' by
> now)...
Pin 2 (high density, or low current,...) is of course now used by 1.2meg
drives. What I was trying to point out was that a pin 2 signal was not
required by any of the 360K drives used on the PC (and was not output by
most, but not all, controllers of the era including the original PC's own
controller).
Sorry about the "no" comment - I should have made it more clear what I was
referring to...
What I was referring to is that 800.com is not formatting the disk using the
drive's "high density" mode. It is telling the drive to use the lower write
current setting (same as with 360K drives), is writing the same bit density
as on 360K drives, but is formatting twice as many tracks (80 instead of
40). That is why this "trick" works successfully with a standard DSDD disk,
and does not require use of "high density" disks.
It is only if you want to push the bit density higher (allowing 1.2Meg
formatting) that the higher write current and special disk media are
required.
- Henry
Charles Sullivan
<snip>
> purposes" only - even address space for third & fourth floppy drives
> was removed (registers for C & D floppy are 'reserved' or 'unused' by
> now)...
Most of the newer motherboards now support only a single floppy drive
(although it can be any of the standard 3.5" or 5.25" types).
The (onboard) FD controller lines formerly used for the second floppy
are non-functional, and at least on my M/B, the I/O address 3F6h
(in the range 3F0-3F7 used for flops) is taken over by the Bus Master
IDE Controller.
(If anyone knows of an add-on PCI card which allows using additional
floppies - they don't need to be bootable and can work through a
driver - I'd appreciate hearing about it.)
Regards,
Charles Sullivan
SeanB51229
> Most of the newer motherboards now support only
> a single floppy drive . . .
That's terrible ! It seems that for every step forward,
we take two steps back. I realise that most new PCs
come with only one floppy drive, but I am so used to
having two (surely an artifact from my pre-hard drive
days) that I make it a point to have two in every
computer I own.
Sean Bernard
SeanB...@aol.com
Outsider
>
> Artur Yelchishchev <ris...@datanet.ee> wrote in message
> news:gi3dhs4fprlkc3n33...@4ax.com...
> <snip>
> > purposes" only - even address space for third & fourth floppy drives
> > was removed (registers for C & D floppy are 'reserved' or 'unused' by
> > now)...
> <snip>
>
> The (onboard) FD controller lines formerly used for the second floppy
> are non-functional, and at least on my M/B, the I/O address 3F6h
> (in the range 3F0-3F7 used for flops) is taken over by the Bus Master
> IDE Controller.
Very sad :-(.
> (If anyone knows of an add-on PCI card which allows using additional
> floppies - they don't need to be bootable and can work through a
> driver - I'd appreciate hearing about it.)
>
I have an ISA card which supports two IDE hard disks and two floppy
drives. I never used it but am keeping it around just in case i need
it. Perhaps there is a PCI model?
On the box it says, "Vitex Interface Card".
From a little paper that comes with it:
MP755 ISA Enhanced Multi I/O User's Manual
IDE interface control two IDE hard disk
Two Floppy Disk Controller from 360K to 2.88M(5 type)
Two high speed NS16C550 compatible RS-232 Serial Port with 16 Byte-FIFO
One Game Port
One Infrared Interface Port
One Multi-Mode Parallel Port with ChiProtect Circuitry Support
Standard Parallel Port (SPP)
Enhanced Parallel Port (EPP)
Enhanced Capabilities Port (ECP)
--
Outsider
MS-DOS 6.22, Windows for Workgroups 3.11, Netscape Navigator 4.08
Terrorism: deadly violence against humans and other living things,
usually conducted by government against its own people.
- Edward Abbey
Outsider
>
> "Charles Sullivan" <csul...@triad.rr.com> says :
>
> > Most of the newer motherboards now support only
>
> That's terrible ! It seems that for every step forward,
> we take two steps back. I realise that most new PCs
> come with only one floppy drive, but I am so used to
> having two (surely an artifact from my pre-hard drive
> days) that I make it a point to have two in every
> computer I own.
Yes, me too (even though I only own one computer). I simply must
have A and B floppies. Suppose you want to copy diskettes?
Suppose one floppy breaks down?
Artur Yelchishchev
<csul...@triad.rr.com> wrote:
-snip-
>(If anyone knows of an add-on PCI card which allows using additional
>floppies - they don't need to be bootable and can work through a
>driver - I'd appreciate hearing about it.)
I've never heard about PCI FDC, but ISA cards (so-called 'Multi I/O')
capable to switch to Secondary FDC are quite common here.
One problem is, that in PC AT architecture floppy and hard disk
controllers use one shared register (diagnostic IIRC), so using the
card is not easy task. I've tried this many times (to hook 360kb drive
in addition to existing 3" & 5" ones), and maximum level of success
achieved was the secondary FDC recognized by TeleDisk utility (both
reading & writing OK); and my attempts to assign drive letters in DOS
were negative (I've played with Driver.Sys and Driveparam commands).
One more thing possibly preventing success here is interrupt line;
even when FDC was configured as Secondary, it still hardwired to IRQ6
(while HDC has jumper for switching to IRQ15 if used as Secondary
HDC). I know little about how DOS really uses floppy IRQs, but maybe
it was the problem (Once again: TeleDisk worked just fine in such a
configuration).
If anyone knows Config.Sys & Autoexec.Bat parameters required to use
floppy drive on Secondary FDC I'll be glad to see them!
Regards,
Artur.
Artur Yelchishchev
<nonvali...@yahoo.com> wrote:
-snip-
>I have an ISA card which supports two IDE hard disks and two floppy
>drives. I never used it but am keeping it around just in case i need
>it. Perhaps there is a PCI model?
Hi Outsider,
Please see my F/U to Mr. Sullivan earlier!
Artur.
Outsider
I read your message. Wow, too bad it is so hard to make it
work.
Outsider
I don't know about that, but drivparm could _possibly_ be used to
help with drive compatibility problems.
http://users.cybercity.dk/~bse26236/batutil/help/DRIVPARS.HTM
--
Outsider
MS-DOS 6.22, Windows for Workgroups 3.11, Netscape Navigator 4.08
Mike Kenzie
> SeanB51229 wrote:
>> "Charles Sullivan" <csul...@triad.rr.com> says :
>> > Most of the newer motherboards now support only
>> > a single floppy drive . . .
>> That's terrible ! It seems that for every step forward,
>> we take two steps back. I realise that most new PCs
>> come with only one floppy drive, but I am so used to
>> having two (surely an artifact from my pre-hard drive
>> days) that I make it a point to have two in every
>> computer I own.
>
> Yes, me too (even though I only own one computer). I simply must
> have A and B floppies. Suppose you want to copy diskettes?
> Suppose one floppy breaks down?
I've gotten around this problem by installing a small network. I now have
my choice of CPU, and hardware I just connect the machines with the
hardware I need. With linux I can get the 386's and 486's connected
easily and the 286's and Xt's can connect as terminals and I'm sure if I
work at it I can get a TCP/IP stack running on them as well.
Artur Yelchishchev
<nonvali...@yahoo.com> wrote:
>> If anyone knows Config.Sys & Autoexec.Bat parameters required to use
>> floppy drive on Secondary FDC I'll be glad to see them!
>
>I don't know about that, but drivparm could _possibly_ be used to
>help with drive compatibility problems.
>http://users.cybercity.dk/~bse26236/batutil/help/DRIVPARS.HTM
Good text - but seems to be just a quote from MS-DOS manual?
And once again: in my experience, the problem was not in
'compatibility' or fine-tuning of drive settings - it was not
recognized _at all_ by DOS...
Artur.
Rez
> Most of the newer motherboards now support only a single floppy drive
I've seen that. I'd like to smack 'em one for that. :(
> (If anyone knows of an add-on PCI card which allows using additional
> floppies - they don't need to be bootable and can work through a
> driver - I'd appreciate hearing about it.)
Far as I know the only ones around are the XT-style 4-floppy
controllers. Tho that is an 8bit board and who knows if its old 16bit
driver would work under Win32. Also what hardware they support may vary
-- might only speak to 360k floppies, or might do all the standard ones.
I wonder if one of the tape drive accellerator cards, which were really
just glorified floppy controllers, might work? Tho am not sure any of
them can override a BIOS that only knows about one floppy.
~REZ~
me
>
> Charles Sullivan wrote:
> >
> > Artur Yelchishchev <ris...@datanet.ee> wrote in message
> > news:gi3dhs4fprlkc3n33...@4ax.com...
> > <snip>
> > > purposes" only - even address space for third & fourth floppy drives
> > > was removed (registers for C & D floppy are 'reserved' or 'unused' by
> > > now)...
> > <snip>
> >
> > (although it can be any of the standard 3.5" or 5.25" types).
> > are non-functional, and at least on my M/B, the I/O address 3F6h
> > (in the range 3F0-3F7 used for flops) is taken over by the Bus Master
> > IDE Controller.
>
> Very sad :-(.
>
> > floppies - they don't need to be bootable and can work through a
> > driver - I'd appreciate hearing about it.)
> >
>
> drives. I never used it but am keeping it around just in case i need
> it. Perhaps there is a PCI model?
>
>
> From a little paper that comes with it:
>
> MP755 ISA Enhanced Multi I/O User's Manual
> IDE interface control two IDE hard disk
> Two Floppy Disk Controller from 360K to 2.88M(5 type)
> Two high speed NS16C550 compatible RS-232 Serial Port with 16 Byte-FIFO
> One Game Port
> One Infrared Interface Port
> One Multi-Mode Parallel Port with ChiProtect Circuitry Support
> Standard Parallel Port (SPP)
> Enhanced Parallel Port (EPP)
> Enhanced Capabilities Port (ECP)
>
> Outsider
> MS-DOS 6.22, Windows for Workgroups 3.11, Netscape Navigator 4.08
> Terrorism: deadly violence against humans and other living things,
> usually conducted by government against its own people.
> - Edward Abbey
*Almost* all of the older I/O controller cards that had a floppy
controller were for *primary* only and handled floppy #0 (Drive A) and
floppy #1 (Drive B) only.
If you use one of these cards, disable everything on the card except
the FDC, and in the BIOS disable the motherboards FDC; this prevents
conflicts.
Doing that, one can run 2 floppy drives.
There were a few special FDC cards that either handled up to four
floppies, or could be jumpered as secondary controllers.
The best one was the Compaticard IV, which could handle all 5.25 inch
formats (320/360K, 1.2M both FD styles, and 800K), two 3.5 inch formats
(720K, 1.44M), and 8 inch drives; up to four drives.
Outsider
>
> Outsider wrote:
> >
> >
> > I have an ISA card which supports two IDE hard disks and two floppy
> > drives. I never used it but am keeping it around just in case i need
> > it. Perhaps there is a PCI model?
> >
> > On the box it says, "Vitex Interface Card".
> >
>
> *Almost* all of the older I/O controller cards that had a floppy
> controller were for *primary* only and handled floppy #0 (Drive A) and
> floppy #1 (Drive B) only.
> If you use one of these cards, disable everything on the card except
> the FDC, and in the BIOS disable the motherboards FDC; this prevents
> conflicts.
> Doing that, one can run 2 floppy drives.
> There were a few special FDC cards that either handled up to four
> floppies, or could be jumpered as secondary controllers.
> The best one was the Compaticard IV, which could handle all 5.25 inch
> formats (320/360K, 1.2M both FD styles, and 800K), two 3.5 inch formats
> (720K, 1.44M), and 8 inch drives; up to four drives.
I only bought this card last year, so I don't think it is that old.
Do you know if Compaticard still makes a card?
Ralf A. Quint
<csul...@triad.rr.com> wrote:
>Most of the newer motherboards now support only a single floppy drive
>(although it can be any of the standard 3.5" or 5.25" types).
>The (onboard) FD controller lines formerly used for the second floppy
>are non-functional, and at least on my M/B, the I/O address 3F6h
>(in the range 3F0-3F7 used for flops) is taken over by the Bus Master
>IDE Controller.
>
Which motherboard supports only one floppy drive ?
I have installed both 3.5" and 5.25" drives (A: AND B:) on a couple of
recent motherboards (INtel CC820, Matsonic 7112C and others) without
any problems .
Charles Sullivan
news:pcbjhs0drllaaqc1h...@4ax.com...
That's interesting - how did you do it? The Technical Specs for the
Intel CC820 say you can't. Go to:
http://www.intel.com/design/motherbd/cc/cc_prdoc.htm
and pull up spec 74847502.PDF which is a link on that page.
The logic diagram for the FDC on Page 59 of that spec indicates that
pins 12 and 16 (which are the Drive-Select and Motor-On pins for the
second drive, drive B:) are not connected.
Elsewhere in that same spec they show the BIOS setup screens. There
is a choice of drives for Drive A: but nothing for Drive B:.
I don't know anything about the Matsonic M/B you mention.
On my M/B, an Intel 440BX OEM version, if you attempt to access
Drive B:, it just renames A: to B:.
Regards,
Charles Sullivan
Charles Sullivan
news:3918F25D...@yahoo.com...
> Charles Sullivan wrote:
> >
> > Artur Yelchishchev <ris...@datanet.ee> wrote in message
> > news:gi3dhs4fprlkc3n33...@4ax.com...
> > <snip>
> > > purposes" only - even address space for third & fourth floppy drives
> > > was removed (registers for C & D floppy are 'reserved' or 'unused' by
> > > now)...
> > <snip>
> >
> > (although it can be any of the standard 3.5" or 5.25" types).
> > The (onboard) FD controller lines formerly used for the second floppy
> > are non-functional, and at least on my M/B, the I/O address 3F6h
> > (in the range 3F0-3F7 used for flops) is taken over by the Bus Master
> > IDE Controller.
>
>
> > (If anyone knows of an add-on PCI card which allows using additional
> > floppies - they don't need to be bootable and can work through a
> > driver - I'd appreciate hearing about it.)
> >
>
> drives. I never used it but am keeping it around just in case i need
> it. Perhaps there is a PCI model?
>
> On the box it says, "Vitex Interface Card".
>
>
> MP755 ISA Enhanced Multi I/O User's Manual
> IDE interface control two IDE hard disk
> Two Floppy Disk Controller from 360K to 2.88M(5 type)
> Two high speed NS16C550 compatible RS-232 Serial Port with 16 Byte-FIFO
> One Game Port
> One Infrared Interface Port
> One Multi-Mode Parallel Port with ChiProtect Circuitry Support
> Standard Parallel Port (SPP)
> Enhanced Parallel Port (EPP)
> Enhanced Capabilities Port (ECP)
The problem is that the newer BIOSes won't support two drives,
so even though you've got the hardware, the BIOS won't know
how to use it. I suppose one could write a driver for the second
FD - assuming there's no conflict with I/O addresses (which appears
to be the problem on my M/B).
Do the specs for your MP755 indicate the I/O addresses used?
me
>
> Ralf A. Quint <ralf_...@hotmail.com> wrote in message
> news:pcbjhs0drllaaqc1h...@4ax.com...
> > On Wed, 10 May 2000 03:11:21 GMT, "Charles Sullivan"
> > <csul...@triad.rr.com> wrote:
> >
> > >(although it can be any of the standard 3.5" or 5.25" types).
> > >The (onboard) FD controller lines formerly used for the second floppy
> > >are non-functional, and at least on my M/B, the I/O address 3F6h
> > >(in the range 3F0-3F7 used for flops) is taken over by the Bus Master
> > >IDE Controller.
> > >
> > I have installed both 3.5" and 5.25" drives (A: AND B:) on a couple of
> > recent motherboards (INtel CC820, Matsonic 7112C and others) without
> > any problems .
>
> That's interesting - how did you do it? The Technical Specs for the
> Intel CC820 say you can't. Go to:
> http://www.intel.com/design/motherbd/cc/cc_prdoc.htm
> and pull up spec 74847502.PDF which is a link on that page.
> The logic diagram for the FDC on Page 59 of that spec indicates that
> pins 12 and 16 (which are the Drive-Select and Motor-On pins for the
> second drive, drive B:) are not connected.
>
> Elsewhere in that same spec they show the BIOS setup screens. There
> is a choice of drives for Drive A: but nothing for Drive B:.
>
> I don't know anything about the Matsonic M/B you mention.
>
> On my M/B, an Intel 440BX OEM version, if you attempt to access
> Drive B:, it just renames A: to B:.
>
> Regards,
> Charles Sullivan
Most motherboards (at least all of those i have seen) support two
floppy drives.
All motherboards from the 8088 PC to the present Pentium 3's will
emulate drive B as you mention if one has only floppy A installed.
That scheme allows one to COPY A:<files> B: and prompts you to switch
floppies (source, destination) until done.
Ralf A. Quint
<csul...@triad.rr.com> wrote:
>Ralf A. Quint <ralf_...@hotmail.com> wrote in message
>news:pcbjhs0drllaaqc1h...@4ax.com...
>> Which motherboard supports only one floppy drive ?
>> I have installed both 3.5" and 5.25" drives (A: AND B:) on a couple of
>> recent motherboards (INtel CC820, Matsonic 7112C and others) without
>> any problems .
>
>That's interesting - how did you do it? The Technical Specs for the
>Intel CC820 say you can't. Go to:
> http://www.intel.com/design/motherbd/cc/cc_prdoc.htm
>and pull up spec 74847502.PDF which is a link on that page.
>The logic diagram for the FDC on Page 59 of that spec indicates that
>pins 12 and 16 (which are the Drive-Select and Motor-On pins for the
>second drive, drive B:) are not connected.
>
Ok, i won't bet on the CC820 right now, as i might be mistaken. I
don't have another board here right now and the one that we put into a
customer's system last month is not accessible for me right now. But
as i used other 820 chip set boards that can access both drives, i
would wonder why this one won't, even though the PDF manual states
otherwise (well, the errata doesn't mention anything (yet).
>I don't know anything about the Matsonic M/B you mention.
>
before i posted this, I've checked it again on two of the newer PIII
boards that i have here in the shop right now. The Matsonic 7112C (VIA
APOLLO chip set) definitely supports two floppy drives, even with swap
between A: and B:, i use it here at my office machine with both 3.5"
and 1.2" drive.
We have customer's machine in with an ASUS P3C2000 board (Intel 820
chip set), and it also allows 2 floppy drives (tried both 3.5" and
5.25" drives a couple of minutes ago).
>On my M/B, an Intel 440BX OEM version, if you attempt to access
>Drive B:, it just renames A: to B:.
>
At home i have a W2K machine with a 440BX2 motherboard, which has both
floppy type drives too.
>Regards,
>Charles Sullivan
We will get some other boards for testing in the next two weeks and i
will check these out for this. I know that Intel is trying to drop all
the legacy stuff (the CC820 has no ISA slots anymore for example, and
they show already boards that don't even have serial, parallel or PS/2
connectors anymore), but i hope that at least other manufacturers are
still making boards that support at least not only USB floppies.
Ralf
Henry Broekhuyse
> > The best one was the Compaticard IV, which could handle all 5.25 inch
> > formats (320/360K, 1.2M both FD styles, and 800K), two 3.5 inch formats
> > (720K, 1.44M), and 8 inch drives; up to four drives.
>
> I only bought this card last year, so I don't think it is that old.
> Do you know if Compaticard still makes a card?
You were actually very "lucky" to have been able to buy one of these cards -
did you get it used or from someone with new "old stock"?
Microsolutions has not been producing the Compaticard (of which the model IV
was the last) for many years now. This card was one of the few (and AFAIK
the most "popular") controller card for connecting 8" drives to a PC.
Incidentally, it is still possible to connect an 8" drive to a PC with most
(but not all) of the "older" floppy controller boards if an appropriate
adapter cable is built, and using Sydex's "22Disk" software. There is a
thorough discussion of the technical details in the comp.os.cpm FAQ (not
recently updated, but available on the web in various locations). There have
also been several discussions regarding the technical "pitfalls" on the
comp.os.cpm newsgroup over the past year, particularly with regard to the
problem of reading single density disks, which is coincidentally still
supported by some but not all controllers.
- Henry
Charles Sullivan
news:3919E927...@earthlink.net...
> Charles Sullivan wrote:
> >
> > Ralf A. Quint <ralf_...@hotmail.com> wrote in message
> > news:pcbjhs0drllaaqc1h...@4ax.com...
> > > <csul...@triad.rr.com> wrote:
> > >
> > > >Most of the newer motherboards now support only a single floppy drive
> > > >(although it can be any of the standard 3.5" or 5.25" types).
> > > >The (onboard) FD controller lines formerly used for the second floppy
> > > >are non-functional, and at least on my M/B, the I/O address 3F6h
> > > >(in the range 3F0-3F7 used for flops) is taken over by the Bus Master
> > > >IDE Controller.
> > > >
> > > I have installed both 3.5" and 5.25" drives (A: AND B:) on a couple of
> > > recent motherboards (INtel CC820, Matsonic 7112C and others) without
> > > any problems .
> >
> > That's interesting - how did you do it? The Technical Specs for the
> > Intel CC820 say you can't. Go to:
> > http://www.intel.com/design/motherbd/cc/cc_prdoc.htm
> > and pull up spec 74847502.PDF which is a link on that page.
> > The logic diagram for the FDC on Page 59 of that spec indicates that
> > pins 12 and 16 (which are the Drive-Select and Motor-On pins for the
> > second drive, drive B:) are not connected.
> >
> > is a choice of drives for Drive A: but nothing for Drive B:.
> >
> >
> > Drive B:, it just renames A: to B:.
> >
> > Charles Sullivan
>
> Most motherboards (at least all of those i have seen) support two
> floppy drives.
> All motherboards from the 8088 PC to the present Pentium 3's will
> emulate drive B as you mention if one has only floppy A installed.
> That scheme allows one to COPY A:<files> B: and prompts you to switch
> floppies (source, destination) until done.
All I can say is if your requirements include two floppy drives,
look very carefully at the detailed M/B specifications - support for
only one floppy drive is often not obvious from the quickie features
sheet. My recollection is that the CC820 quickie sheet says something
like "one floppy controller", and you'll be wrong if you assume this
is the same old PC/AT controller you're familiar with, where one controller
supports two floppy drives.
I'd venture to guess that 99.9% of PC users have no need for more than
the single 3.5" floppy which is standard on most PCs (disregarding ZIP
drives and such). So even many PC technicians are unaware of this
one-drive limitation until it's brought to their attention.
Regards,
Charles Sullivan
Outsider
> > Charles Sullivan wrote:
> > >
> > > Artur Yelchishchev <ris...@datanet.ee> wrote in message
> > > news:gi3dhs4fprlkc3n33...@4ax.com...
> > > <snip>
> > > > purposes" only - even address space for third & fourth floppy drives
> > > > was removed (registers for C & D floppy are 'reserved' or 'unused' by
> > > > now)...
> > > <snip>
> > >
> > > (although it can be any of the standard 3.5" or 5.25" types).
> > > The (onboard) FD controller lines formerly used for the second floppy
> > > are non-functional, and at least on my M/B, the I/O address 3F6h
> > > (in the range 3F0-3F7 used for flops) is taken over by the Bus Master
> > > IDE Controller.
> >
No, it only gives the jumper settings.
Function Select (jumper2)
Position Jumper Off Jumper On
IDE 1/2 (IDE 1 & IDE 2 select) IDE 1* IDE 2
FDD E/D (FDD Enable/Disable select) Enable* Disable
IDE IRQ Select (jumper3)
Item 1.2 Pin Short 2.3 Pin Short
IDE IRQ14/15 IRQ14* IRQ15
*Factory default setting
Outsider
> > > The best one was the Compaticard IV, which could handle all 5.25 inch
> > > formats (320/360K, 1.2M both FD styles, and 800K), two 3.5 inch formats
> > > (720K, 1.44M), and 8 inch drives; up to four drives.
> >
> > I only bought this card last year, so I don't think it is that old.
> > Do you know if Compaticard still makes a card?
>
> You were actually very "lucky" to have been able to buy one of these cards -
> did you get it used or from someone with new "old stock"?
I bought it new in an unopened box. According to a manufacturers
sticker on the card itself, it was produced in May 1998. I picked
it out of a computer store's product catalog.
> Microsolutions has not been producing the Compaticard (of which the model IV
> was the last) for many years now. This card was one of the few (and AFAIK
> the most "popular") controller card for connecting 8" drives to a PC.
> Incidentally, it is still possible to connect an 8" drive to a PC with most
> (but not all) of the "older" floppy controller boards if an appropriate
> adapter cable is built, and using Sydex's "22Disk" software. There is a
> thorough discussion of the technical details in the comp.os.cpm FAQ (not
> recently updated, but available on the web in various locations). There have
> also been several discussions regarding the technical "pitfalls" on the
> comp.os.cpm newsgroup over the past year, particularly with regard to the
> problem of reading single density disks, which is coincidentally still
> supported by some but not all controllers.
>
> - Henry
Thanks for the update.
me
>
> me <rober...@earthlink.net> wrote in message
> news:3919E927...@earthlink.net...
> > Charles Sullivan wrote:
> > >
> > > Ralf A. Quint <ralf_...@hotmail.com> wrote in message
> > > news:pcbjhs0drllaaqc1h...@4ax.com...
> > > > On Wed, 10 May 2000 03:11:21 GMT, "Charles Sullivan"
> > > > <csul...@triad.rr.com> wrote:
> > > >
> > > > >(although it can be any of the standard 3.5" or 5.25" types).
> > > > >The (onboard) FD controller lines formerly used for the second floppy
> > > > >are non-functional, and at least on my M/B, the I/O address 3F6h
> > > > >(in the range 3F0-3F7 used for flops) is taken over by the Bus Master
> > > > >IDE Controller.
> > > > >
I am an electronic tech since the daze of 4,5,6 etc pin tubes,
designed my own computer, and have worked on computers since IBM came
out with the PCXT, and have *yet* to actually see this "limitation".
However, there are so many companies out there that want to try to be
different, cheaper (read: greedy), etc that i will not rule out the
possibility that there may be motherboards that support only one FD.
Charles Sullivan
None of the Pentium II or III M/Bs in Intel's current production support
more than one floppy drive. See http://www.intel.com/design/motherbd
(A few of the ones they list as "retired" do.)
Mike Webb
my user group meetings. I still use 5.25" floppies of both kinds
periodically, and the bottom line is still; BE CAREFUL. Since you're dealing
with a 40-track format (360K) in an 80-track (1.2M) drive, you CAN make the
floppy unreadable in a 40-track drive by writing to it on an 80-track drive.
Sometimes it works fine, sometimes not. But regardless, it should still be
readable in the 80-track drive.
Ed, I don't have your original post, but here are some general guidelines in
dealing with these diskettes;
1) If you have data or programs on 360K diskettes and you intend to interact
with those older files, I'd advise using your 1.2M drive to copy them either
to your hard drive or to high density diskettes.
2) If you have 360K disks that you want to use, apply 1) to the files you
want to make sure you keep. Then (depending on what you have), run a bulk
tape eraser over the disks (keeping that operation WELL AWAY from your other
disks), use a strong magnet for the same purpose, or use the BULKERAS program
that came with CopyIIPC if you happen to have it. Then reformat them in your
machine, either using "FORMAT B: /4" or "FORMAT B: /F:360" (I'm assuming your
1.2M drive is the B: drive) and use them only on a 1.2M drive. If you have a
machine you're using that has a 360K drive, you don't need to bulk-erase the
disks you're going to use on it, just reformat 'em fresh to make sure they're
still good.
3) If you need to use the disks to move data from one computer to another,
use the disks formatted by the 360K drive to take data from the 360K drive to
the 1.2M drive and ONLY copy the data to the other machine (no write action).
And going the other way, use only the bulk-erased disks formatted on the 1.2M
drive to copy data to on the 1.2M drive and ONLY copy the data to the machine
with the 360K drive. It may seem a little paranoid, but the basic question
is; what's your data worth? You might be able to swap back and forth between
the two machines with each drive writing to it, but there is a risk that it
won't work and you'll end up with a jumbled-up disk.
HTH!
> From: "Charles Sullivan" <csul...@triad.rr.com>
> Date: Tue, 02 May 2000 02:51:35 GMT
> Ed Ngai <en...@sprintmail.com> wrote...
> > Charles Sullivan wrote:
> > > When the 1.2 Meg 5.25" floppy drive was introduced with the IBM-AT,
> > > there was a specific warning that writing to a 360K diskette would
> > > render it unreadable on a 360K drive. (The narrower write head of
> > > the 1.2 Meg drive would leave fringes of the wider 360K track.)
> > This is wrong. I still have a 360k and 1.2M floppy drive and you
> > have to FORMAT the 360k in a 1.2M fd w/ the correct DOS FORMAT
> > command.
> Ed,
> What is the age of your 1.2 Meg drive? My old 1.2 Meg Teac is vintage
> 1990. I could take a 360K diskette formatted on a 360K drive, write to
> it with the 1.2 Meg drive, then satisfactorally read the diskette in a
> 360K drive. Others have told me they could do the same thing with
> later model 1.2 Meg drives but not with the drives shipped with the
> original IBM-AT. This is not something that was specified by Teac
> but it did seem to work.
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Before you buy.
MasterF
computer. Dont know what PCI or ISA mean.
Outsider wrote in message <3918F25D...@yahoo.com>...
>Charles Sullivan wrote:
>>
>> Artur Yelchishchev <ris...@datanet.ee> wrote in message
>> news:gi3dhs4fprlkc3n33...@4ax.com...
>> <snip>
>> > purposes" only - even address space for third & fourth floppy drives
>> > was removed (registers for C & D floppy are 'reserved' or 'unused' by
>> > now)...
>> <snip>
>>
>> (although it can be any of the standard 3.5" or 5.25" types).
>> The (onboard) FD controller lines formerly used for the second floppy
>> are non-functional, and at least on my M/B, the I/O address 3F6h
>> (in the range 3F0-3F7 used for flops) is taken over by the Bus Master
>> IDE Controller.
>
>
>> (If anyone knows of an add-on PCI card which allows using additional
>> floppies - they don't need to be bootable and can work through a
>> driver - I'd appreciate hearing about it.)
>>
>
>I have an ISA card which supports two IDE hard disks and two floppy
>drives. I never used it but am keeping it around just in case i need
>it. Perhaps there is a PCI model?
>
>On the box it says, "Vitex Interface Card".
>
>From a little paper that comes with it:
>
>MP755 ISA Enhanced Multi I/O User's Manual
>IDE interface control two IDE hard disk
>Two Floppy Disk Controller from 360K to 2.88M(5 type)
>Two high speed NS16C550 compatible RS-232 Serial Port with 16 Byte-FIFO
>One Game Port
>One Infrared Interface Port
>One Multi-Mode Parallel Port with ChiProtect Circuitry Support
> Standard Parallel Port (SPP)
> Enhanced Parallel Port (EPP)
> Enhanced Capabilities Port (ECP)
>
>
>Outsider
>MS-DOS 6.22, Windows for Workgroups 3.11, Netscape Navigator 4.08
MasterF
disk drive adress to a com-port ot install an external disk drive which I
have?
Artur Yelchishchev wrote in message ...>-snip-
>>(If anyone knows of an add-on PCI card which allows using additional
>>floppies - they don't need to be bootable and can work through a
>>driver - I'd appreciate hearing about it.)
>
>capable to switch to Secondary FDC are quite common here.
>
>One problem is, that in PC AT architecture floppy and hard disk
>controllers use one shared register (diagnostic IIRC), so using the
>card is not easy task. I've tried this many times (to hook 360kb drive
>in addition to existing 3" & 5" ones), and maximum level of success
>achieved was the secondary FDC recognized by TeleDisk utility (both
>reading & writing OK); and my attempts to assign drive letters in DOS
>were negative (I've played with Driver.Sys and Driveparam commands).
>
>One more thing possibly preventing success here is interrupt line;
>even when FDC was configured as Secondary, it still hardwired to IRQ6
>(while HDC has jumper for switching to IRQ15 if used as Secondary
>HDC). I know little about how DOS really uses floppy IRQs, but maybe
>it was the problem (Once again: TeleDisk worked just fine in such a
>configuration).
>
>floppy drive on Secondary FDC I'll be glad to see them!
>
>Artur.
>
MasterF
load.
Charles Sullivan wrote in message ...
>me <rober...@earthlink.net> wrote in message
>news:391AE512...@earthlink.net...
>> Charles Sullivan wrote:
>> >
>> > me <rober...@earthlink.net> wrote in message
>> > news:3919E927...@earthlink.net...
>> > > Charles Sullivan wrote:
>> > > >
>> > > > Ralf A. Quint <ralf_...@hotmail.com> wrote in message
>> > > > news:pcbjhs0drllaaqc1h...@4ax.com...
>> > > > > <csul...@triad.rr.com> wrote:
>> > > > >
>drive
>> > > > > >(although it can be any of the standard 3.5" or 5.25" types).
>> > > > > >The (onboard) FD controller lines formerly used for the second
>floppy
>> > > > > >are non-functional, and at least on my M/B, the I/O address 3F6h
>> > > > > >(in the range 3F0-3F7 used for flops) is taken over by the Bus
>Master
>> > > > > >IDE Controller.
>> > > > > >
MasterF
Artur Yelchishchev wrote in message ...
><maxi...@geocities.com.nospam> wrote:
>
>>Would it be possible to re-program the computer temporarlily to re-direct
a
>>disk drive adress to a com-port ot install an external disk drive which I
>>have?
>
>adress to a com-port' - your external drive must have appropriate
>device driver software, and this isn't 'redirection' - just normal
>operation mode. I've never heard about using COM ports for ext.
>drives; common way is to use parallel (LPT) for this: many times
>faster and doesn't require voltage levels conversion.
>
>Regards,
>Artur.
>
Artur Yelchishchev
MasterF
Artur Yelchishchev wrote in message
>On Sun, 14 May 2000 14:04:23 +1200, "MasterF"
><maxi...@geocities.com.nospam> wrote:
>
>>oh. Well I dont have a driver, so what can I do?
>
>
>Artur.
Artur Yelchishchev
Dan O'Quinn
number of ways to add second floppy support (or third) to a system designed
for one floppy drive.
there were two different methods one used a device driver the other was a
sector edited and modified bootstrap. I still have that info somewhere, if
anyone thinks it might be applicable I'll try to locate it but I haven't
seen it in 15+ years so it may take a while to locate.
Dan O'Quinn
tweeks
>
> Charles Sullivan wrote:
> >
> > When the 1.2 Meg 5.25" floppy drive was introduced with the IBM-AT,
> > there was a specific warning that writing to a 360K diskette would
> > render it unreadable on a 360K drive. (The narrower write head of
> > the 1.2 Meg drive would leave fringes of the wider 360K track.)
> >
> > not to have this problem. I was concurrently running two systems
> > for a number of years, the older of which was equipped with only 360K
> > drives, and I don't recollect ever having problem reading 360K
> > diskettes on a 360K drive which were written to with a 1990-vintage
> > 1.2 Meg drive (a Teac FD55GFR-142-U).
> >
> > Others have mentioned that although they had write-compatibility
> > problems with the original IBM-AT, they too were able to read
> > diskettes on a 360K drive which had been written by the 1.2 Meg drive
> > on later clone systems.
> >
> > Somebody told me at the time they thought the later drives had a dual
> > head arrangement whereby the drive could write either the narrow
> > track for 1.2 Meg diskettes or a wider track for 360K diskettes. But
> > to my surprise the specs for this same Teac drive say that 360K is
> > read-only - nothing about dual heads or write compatibility.
> >
> > Are there any old-timers out there who know what changes were made
> > to later model 1.2 Meg drives to allow write-compatibility with 360K
> > drives? (The tech at Teac I spoke to was too young to remember any
> > of this.)
> >
> > Regards,
> > Charles Sullivan cwsu...@triad.rr.com
>
[...]
> As I remember, the drives were modified to lay down FOUR IDENTICAL BITS
> in a row when writing 360's. This approximated the width of the bits on
> the lower density media. That made it reasonably likely the older
> drives could read the disks written by the newer ones. As far as I
> recall it was never a problem of reading 360's on 1.2's, just the other
> way around.
Wasn't there also a problem if you wrote a 360k format to a 1.2M disk that the
flud density needed to format the HD media could not be reliably writen to in a
360k DSDD drive?
Tom D Tek
tweeks
>
> Rez wrote:
>
> en...@sprintmail.com wrote:
> > > c:\format b: /4 /8 ...and this works just fine, but you
> > > can't use the switch /f:360 , won't work.
>
> > The /f:360 switch works just fine for me. Or do you mean it writes a
> > disk that the old drive can't read? I never found that to be true. I
> > never used the /4 /8 switches, only the /f:360 switch, when doing my
> > extensive test formattings (see othre message). Only thing that ever
> > made a bit of difference was the DOS version.
>
> I'm using MSDOS 6.22 on 1 pc and it wont except the f:/360
> switch.
>
> Who knows ?
> Ed
]
try /f:360 crackhead! ;)
tweeks