1.44mb floppies are HD and these drives should be able to read the DD disks (both of which are 3.5in of course).
I'm not as sure about the 5.25in drives as there were several different densities which were not 100% compatible with each other. Iirc there was HD, DD and QD (quad density).

There's also 3.5in ED disks which basically doubled 3.5in HD disk storage capacity, but I doubt you will run into any such disks anytime soon. These would need a dedicated 2.88mb FDD to be able to read them, but should be able to read 1.44mb floppy disks just fine.

I'm unsure about other standards using the same media. I'm mostly a PC guy but perhaps you could still read the raw data and convert it using software? it really depends on what your plans are.

There was this issue with 5,25 drives. The DD (360kB) drives spin at a different speed then a HD (1,2MB) drive. Some HD drives do have the capability to spin at the speed, but not all.

Besides that, the 360k disk should be formatted in a 360 drive (I prefer twice) before writing data to it in a HD drive. The 360kB disk has a wider track and the DD head is just as wide. The more narrow HD head may leave some data on the edge of the track. No problem it the edge shows zero but other garbage may interfere with the main data.

For DD 720kB / HD 1,44MB / and ED 2,88MB do not share this problem.

So i could use 1.44 and 360k 3.5 drives, and 1.2, and 360k 5.25" drives, and be able to run the 720k disks fine in the larger capacity drive, read/write/format? Apologies for the super basic questions, im 20 and just learning these things 😅

Oooo a floppy discussion! 😀

Some say it is not recommended to use 720kb DD floppies in hd drives and vice versa but it does work in my experience. Something about different magnetic materials or what not, results may vary I suppose.

Fun fact, you can put tape on a hd 3.5 floppy and the sensor in your hd drive will recognize it as a 720 kB disk.

Alistar1776 wrote on 2022-04-27, 18:56:

My question is, can I use a 1.44mb 3.5 drive, to read/write floppies of that capacity or lower, and same for 1.2mb 5.25 drives to read/write floppies that are that capacity or lower? Or do I need dedicated drives for the smaller capacities? I may have to format the floppies as well, so the same questions apply there.

To some extent you can. You should read the wiki articles on floppy disks but in general:
* A 3.5" HD drive should properly read and write DD disks as well, the difference in magnetic material is not that big. The problem might be with some late, "end of line" drives that were made to be cheap. The DD sensor is missing and the drive will assume all disks to be HD, while DOS will refuse to format any floppy not detected as DD to 720k format.
* DD 3.5" PC drives are rare, and the floppies even more so (seems the Amiga crowd used them all up), these drive will struggle to write to HD floppies. It might just work, depending on the particular drive and media. Obviously any HD floppy will be written as DD one.
* 5.25" HD drive will read DD floppies, might be able to write them but that is not guaranteed, and also such floppy might no longer be readable in DD drive. Might need reformatting or even demagnetising pass to "cure" that. To actually properly write to DD floppies you need a DD drive, period.
* 5.25" DD drive will only work with DD floppies. It's heads are not strong enough to write to HD media, most such attempts will fail miserably. Usually it will be able to read HD floppies formatted as DD ones in HD drive only if that floppy was demagnetised first to remove the high density track layout.

Deunan wrote on 2022-04-27, 20:39:

* DD 3.5" PC drives are rare, and the floppies even more so

Not that rare. A lot of mice or Ethernet cards came with DD floppies with drivers, even when HD floppies were otherwise ubiquitous.

Deunan wrote on 2022-04-27, 20:39:

To some extent you can. You should read the wiki articles on floppy disks but in general: * A 3.5" HD drive should properly read […]
Show full quote

Alistar1776 wrote on 2022-04-27, 18:56:

My question is, can I use a 1.44mb 3.5 drive, to read/write floppies of that capacity or lower, and same for 1.2mb 5.25 drives to read/write floppies that are that capacity or lower? Or do I need dedicated drives for the smaller capacities? I may have to format the floppies as well, so the same questions apply there.

To some extent you can. You should read the wiki articles on floppy disks but in general:
* A 3.5" HD drive should properly read and write DD disks as well, the difference in magnetic material is not that big. The problem might be with some late, "end of line" drives that were made to be cheap. The DD sensor is missing and the drive will assume all disks to be HD, while DOS will refuse to format any floppy not detected as DD to 720k format.
* DD 3.5" PC drives are rare, and the floppies even more so (seems the Amiga crowd used them all up), these drive will struggle to write to HD floppies. It might just work, depending on the particular drive and media. Obviously any HD floppy will be written as DD one.
* 5.25" HD drive will read DD floppies, might be able to write them but that is not guaranteed, and also such floppy might no longer be readable in DD drive. Might need reformatting or even demagnetising pass to "cure" that. To actually properly write to DD floppies you need a DD drive, period.
* 5.25" DD drive will only work with DD floppies. It's heads are not strong enough to write to HD media, most such attempts will fail miserably. Usually it will be able to read HD floppies formatted as DD ones in HD drive only if that floppy was demagnetised first to remove the high density track layout.

So HD is like 1.2mb, 1.44mb, the DD would be 720k drives? Just to make sure im understanding correctly.

Alistar1776 wrote on 2022-04-27, 21:28:

Deunan wrote on 2022-04-27, 20:39:

To some extent you can. You should read the wiki articles on floppy disks but in general: * A 3.5" HD drive should properly read […]
Show full quote

Alistar1776 wrote on 2022-04-27, 18:56:

My question is, can I use a 1.44mb 3.5 drive, to read/write floppies of that capacity or lower, and same for 1.2mb 5.25 drives to read/write floppies that are that capacity or lower? Or do I need dedicated drives for the smaller capacities? I may have to format the floppies as well, so the same questions apply there.

To some extent you can. You should read the wiki articles on floppy disks but in general:
* A 3.5" HD drive should properly read and write DD disks as well, the difference in magnetic material is not that big. The problem might be with some late, "end of line" drives that were made to be cheap. The DD sensor is missing and the drive will assume all disks to be HD, while DOS will refuse to format any floppy not detected as DD to 720k format.
* DD 3.5" PC drives are rare, and the floppies even more so (seems the Amiga crowd used them all up), these drive will struggle to write to HD floppies. It might just work, depending on the particular drive and media. Obviously any HD floppy will be written as DD one.
* 5.25" HD drive will read DD floppies, might be able to write them but that is not guaranteed, and also such floppy might no longer be readable in DD drive. Might need reformatting or even demagnetising pass to "cure" that. To actually properly write to DD floppies you need a DD drive, period.
* 5.25" DD drive will only work with DD floppies. It's heads are not strong enough to write to HD media, most such attempts will fail miserably. Usually it will be able to read HD floppies formatted as DD ones in HD drive only if that floppy was demagnetised first to remove the high density track layout.

So HD is like 1.2mb, 1.44mb, the DD would be 720k drives? Just to make sure im understanding correctly.

Indeed.
ED: 3,5" 2,44MB
HD: 3,5" 1,44MB or 5,25" 1,2MB
DD: 3,5" 720kB or 5,25" 360kB
SD: ???

waterbeesje wrote on 2022-04-27, 22:07:

Indeed. ED: 3,5" 2,44MB HD: 3,5" 1,44MB or 5,25" 1,2MB DD: 3,5" 720kB or 5,25" 360kB SD: ??? […]
Show full quote

Alistar1776 wrote on 2022-04-27, 21:28:

Deunan wrote on 2022-04-27, 20:39:

To some extent you can. You should read the wiki articles on floppy disks but in general: * A 3.5" HD drive should properly read […]
Show full quote

To some extent you can. You should read the wiki articles on floppy disks but in general:
* A 3.5" HD drive should properly read and write DD disks as well, the difference in magnetic material is not that big. The problem might be with some late, "end of line" drives that were made to be cheap. The DD sensor is missing and the drive will assume all disks to be HD, while DOS will refuse to format any floppy not detected as DD to 720k format.
* DD 3.5" PC drives are rare, and the floppies even more so (seems the Amiga crowd used them all up), these drive will struggle to write to HD floppies. It might just work, depending on the particular drive and media. Obviously any HD floppy will be written as DD one.
* 5.25" HD drive will read DD floppies, might be able to write them but that is not guaranteed, and also such floppy might no longer be readable in DD drive. Might need reformatting or even demagnetising pass to "cure" that. To actually properly write to DD floppies you need a DD drive, period.
* 5.25" DD drive will only work with DD floppies. It's heads are not strong enough to write to HD media, most such attempts will fail miserably. Usually it will be able to read HD floppies formatted as DD ones in HD drive only if that floppy was demagnetised first to remove the high density track layout.

So HD is like 1.2mb, 1.44mb, the DD would be 720k drives? Just to make sure im understanding correctly.

Indeed.
ED: 3,5" 2,44MB
HD: 3,5" 1,44MB or 5,25" 1,2MB
DD: 3,5" 720kB or 5,25" 360kB
SD: ???

Isnt there 720k 5.25 also? So SD would be the 360k drives on both?

And then next question, will a DD drive, read a HD disk written as a DD disk? Ex. 1.2mb disk, only 720k written on it.

My end goal is to lessen the amount of floppy drives I need, because many cases that I can find, dont have enough drive bays for a CD ROM, 3 5.25 drives, and 3 3.5 drives for every capacity i could need for OS and/or programs for anything id get to work on

Alistar1776 wrote on 2022-04-27, 22:27:

And then next question, will a DD drive, read a HD disk written as a DD disk? Ex. 1.2mb disk, only 720k written on it.

Those two should never meet, 1.2MB is 5 1/4", 720k is 3.5" (unless you use a wierd formatter that may need a TSR for reading - I formatted 5 1/4" DD to 800k that way, but can't remember if they read natively.

If we're talking PC type specifically, the standards were:
1. 5 1/4" DD 40 track 360k
2. 5 1/4" HD 80 track 1.2M (the drive can read 360k by double stepping, but when writing to a 360k, it is writing a half width track and cannot reliably overwrite a true 40 track drive track)
3. 3 1/2" DD 80 track 720k
4. 3 1/2" HD 80 track 1.44M - the drive can switch density signalled by the HD hole and use either 1.44M or 720k
5. 3 1/2" ED 80 track 2.88M (very rare drive & media, didn't really catch on)

Matth79 wrote on 2022-04-27, 23:55:

Those two should never meet, 1.2MB is 5 1/4", 720k is 3.5" (unless you use a wierd formatter that may need a TSR for reading - I […]
Show full quote

Alistar1776 wrote on 2022-04-27, 22:27:

And then next question, will a DD drive, read a HD disk written as a DD disk? Ex. 1.2mb disk, only 720k written on it.

Those two should never meet, 1.2MB is 5 1/4", 720k is 3.5" (unless you use a wierd formatter that may need a TSR for reading - I formatted 5 1/4" DD to 800k that way, but can't remember if they read natively.

If we're talking PC type specifically, the standards were:
1. 5 1/4" DD 40 track 360k
2. 5 1/4" HD 80 track 1.2M (the drive can read 360k by double stepping, but when writing to a 360k, it is writing a half width track and cannot reliably overwrite a true 40 track drive track)
3. 3 1/2" DD 80 track 720k
4. 3 1/2" HD 80 track 1.44M - the drive can switch density signalled by the HD hole and use either 1.44M or 720k
5. 3 1/2" ED 80 track 2.88M (very rare drive & media, didn't really catch on)

Ok. Thats mainly what i was after, most common ones i actually need. I know i couldve just asked that, but it was still a good education to learn what could be done on floppys 😅 i appreciate all the help!

Azarien wrote on 2022-04-27, 20:51:

Deunan wrote on 2022-04-27, 20:39:

* DD 3.5" PC drives are rare, and the floppies even more so

Not that rare. A lot of mice or Ethernet cards came with DD floppies with drivers, even when HD floppies were otherwise ubiquitous.

Afaik, of all the 3.5in FDDs I collected over time, only a single one was a 3.5in DD drive, though last time I checked is like 15 years ago or so (I got all kinds of 3.5in drives as I dumpsterdived them so not all of them may even be PC FDDs).

I don't know how rare the 3.5in DD drives are, but the 3.5in DD disks were really common.

Virtually all the other 3.5in FDDs I found were HD drives except for a few which were 2.88 ED drives.

Deunan wrote on 2022-04-27, 20:39:

To some extent you can. You should read the wiki articles on floppy disks but in general: * A 3.5" HD drive should properly read […]
Show full quote

Alistar1776 wrote on 2022-04-27, 18:56:

My question is, can I use a 1.44mb 3.5 drive, to read/write floppies of that capacity or lower, and same for 1.2mb 5.25 drives to read/write floppies that are that capacity or lower? Or do I need dedicated drives for the smaller capacities? I may have to format the floppies as well, so the same questions apply there.

To some extent you can. You should read the wiki articles on floppy disks but in general:
* A 3.5" HD drive should properly read and write DD disks as well, the difference in magnetic material is not that big. The problem might be with some late, "end of line" drives that were made to be cheap. The DD sensor is missing and the drive will assume all disks to be HD, while DOS will refuse to format any floppy not detected as DD to 720k format.
* DD 3.5" PC drives are rare, and the floppies even more so (seems the Amiga crowd used them all up), these drive will struggle to write to HD floppies. It might just work, depending on the particular drive and media. Obviously any HD floppy will be written as DD one.
* 5.25" HD drive will read DD floppies, might be able to write them but that is not guaranteed, and also such floppy might no longer be readable in DD drive. Might need reformatting or even demagnetising pass to "cure" that. To actually properly write to DD floppies you need a DD drive, period.
* 5.25" DD drive will only work with DD floppies. It's heads are not strong enough to write to HD media, most such attempts will fail miserably. Usually it will be able to read HD floppies formatted as DD ones in HD drive only if that floppy was demagnetised first to remove the high density track layout.

So the huge sea of 3.5in DD disks have all been scooped up? Interesting...

Joakim wrote on 2022-04-27, 20:08:

Oooo a floppy discussion! 😀

Some say it is not recommended to use 720kb DD floppies in hd drives and vice versa but it does work in my experience. Something about different magnetic materials or what not, results may vary I suppose.

Fun fact, you can put tape on a hd 3.5 floppy and the sensor in your hd drive will recognize it as a 720 kB disk.

If you're referring to 3.5in FDDs, I used DD disks in HD drives all the time. It seemed to work perfectly fine for what it was.
I used to use them to transfer data I downloaded to my own PC as I didn't have internet back then (no joke, the ZIP drive I got later was a real saver here xD)

Alistar1776 wrote on 2022-04-27, 22:27:

And then next question, will a DD drive, read a HD disk written as a DD disk? Ex. 1.2mb disk, only 720k written on it.

My end goal is to lessen the amount of floppy drives I need, because many cases that I can find, dont have enough drive bays for a CD ROM, 3 5.25 drives, and 3 3.5 drives for every capacity i could need for OS and/or programs for anything id get to work on

I'd suggest you get a case with enough space to accommodate all the drives you'll need, if only because you can always swap cables around and a larger case usually is easier to work with.
If you want to max flexibility that is.
I doubt btw you'd even need an optical drive in such a system meant to read floppy media. You can always add an optical drive quick if you need to install from some CDROM or something.

Tetrium wrote on 2022-04-28, 09:58:

I'd suggest you get a case with enough space to accommodate all the drives you'll need, if only because you can always swap cabl […]
Show full quote

Alistar1776 wrote on 2022-04-27, 22:27:

And then next question, will a DD drive, read a HD disk written as a DD disk? Ex. 1.2mb disk, only 720k written on it.

My end goal is to lessen the amount of floppy drives I need, because many cases that I can find, dont have enough drive bays for a CD ROM, 3 5.25 drives, and 3 3.5 drives for every capacity i could need for OS and/or programs for anything id get to work on

I'd suggest you get a case with enough space to accommodate all the drives you'll need, if only because you can always swap cables around and a larger case usually is easier to work with.
If you want to max flexibility that is.
I doubt btw you'd even need an optical drive in such a system meant to read floppy media. You can always add an optical drive quick if you need to install from some CDROM or something.

the optical drive would be used for anything that writes to disk, like Win98SE, Win2000, Win XP, ME, software and games and drivers for anything within that era. having the space to have one in the case already and hooked up is just convenience really.

The fancy formatter I used was http://toastytech.com/files/nformat.html - and as I had quite a lot of DD 5 1/4", I used them as 800k - I think my system did handle them without the driver.
Also, the documentation describes the problem with 360k in a 1.2Mb drive... the 80 track drive writes alternate half width tracks, so:
A 1.2MB drive can 100% read a 360k disk. To write a 360k, it needs to be on degaussed media so that there is nothing in the skipped track gaps. That disk MAY read adequately in a 360k drive, but will only be providing 50% of the signal that a native 360k would.
1.44Mb drives should switch density (and drive level) according to the hole present in 1.44Mb disks, so should not have any problem covering 720k as well.
PS. NFORMAT can also generate the Microsoft DMF format using appropriate parameters (21 sectors per track, 16 root directory and 2 or 4 sector clusters)

Question... if a 3.5 1.44mb FDD can read and write 720k 3.5 disks, can those disks still function just fine in a normal 720k FDD?

Alistar1776 wrote on 2022-05-14, 06:42:

Question... if a 3.5 1.44mb FDD can read and write 720k 3.5 disks, can those disks still function just fine in a normal 720k FDD?

Yes they should read fine unless the 720k disk was formatted into a 1.44mb disk. On the ibm ps/2 it was not necessary to have the extra hole to format to 1.44mb either.

Tetrium wrote on 2022-04-28, 09:50:

Virtually all the other 3.5in FDDs I found were HD drives except for a few which were 2.88 ED drives.

How could you tell when you had a 2.88 ED drive without a 2.88mb disk. Is it always on the label?

I have a weird 1.44mb fdd which on the back has less ground pins than normal. I thought they were ripped out and the drive was damaged but when I popped the model into google it seems to be like that. It is a Mitsumi D359m3d https://www.amazon.com/D359M3D-Mitsumi-Floppy … e/dp/B000EISIQ6 . Any ideas know why this is so? Its the only fdd I've seen like this.