Planet-Dune wrote on 2020-03-26, 21:11:

- Can I freely use a 1.2MB floppy to write data to 360KB floppies to be used on a 360KB drive?

No. You can write data to a 360KB disk and keep using that with the 1.2MB drive. A 360KB drive however won't be able to reliably read the disk. That is by design, as the head of a 1.2MB drive is much smaller, leaving junk of data left and right of the track that a 360KB drive will pick up, causing it not to understand what it reads.

Planet-Dune wrote on 2020-03-26, 21:11:

- Can I format a 360KB floppy in a 1.2MB drive? I tried and it weirdly enough said it was "formatting 1.2mb" and then said there were 200kb of bad sectors and 900kb usable (on a 360kb floppy as far as I can tell) but the floppy really didn't work well anymore at that point, especially in the 360kb drive.

You need to tell format that it's a 360KB disk. You can not format it to 1.2MB, for obvious reasons.

derSammler wrote on 2020-03-26, 21:31:

No. You can write data to a 360KB disk and keep using that with the 1.2MB drive. A 360KB drive however won't be able to reliably […]
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Planet-Dune wrote on 2020-03-26, 21:11:

- Can I freely use a 1.2MB floppy to write data to 360KB floppies to be used on a 360KB drive?

No. You can write data to a 360KB disk and keep using that with the 1.2MB drive. A 360KB drive however won't be able to reliably read the disk. That is by design, as the head of a 1.2MB drive is much smaller, leaving junk of data left and right of the track that a 360KB drive will pick up, causing it not to understand what it reads.

Planet-Dune wrote on 2020-03-26, 21:11:

- Can I format a 360KB floppy in a 1.2MB drive? I tried and it weirdly enough said it was "formatting 1.2mb" and then said there were 200kb of bad sectors and 900kb usable (on a 360kb floppy as far as I can tell) but the floppy really didn't work well anymore at that point, especially in the 360kb drive.

You need to tell format that it's a 360KB disk. You can not format it to 1.2MB, for obvious reasons.

Okay, that explains all my frustration... I figured it would work like a 720kb diskette where it can be used in a 1.44mb drive just fine without issues (and then still be readable on a 720 one)...

Well would still be nice to know if there are any good check and format utilities out there or should I just use default format.com ?

FORMAT.COM should be fine. It has various options to check for bad tracks and such; just use the "/?" parameter to get all options listed.

1.2MB and 360K are completely different only in writing heads width track. 360K is wider than 1.2MB also is narrower.

Can read 360K on 1.2MB and can write a blank 360k disk on 1.2MB pretty good but comes up a problem when 360K drive formatted on 360K disk then write on 1.2MB in 360K mode then you have more problems on reading messy 36oK disk in 360K drive due to mixed width on each tracks.

Better find a real 360K drive.

And another issue is 1.2MB write amplification is stronger than 360K meant 1.2MB disk formatted as 360K in 1.2MB drive have hard time writing data hard enough impressions on 36oK drive.

Cheers,

A 3.5" disk I won in an auction is 360k. Wait a moment, isn't this capacity supposed to be for 5.25" disks? 😮

Myloch wrote on 2023-02-14, 14:44:

A 3.5" disk I won in an auction is 360k. Wait a moment, isn't this capacity supposed to be for 5.25" disks? 😮

3.5" Single Sided, Double Density is 360 KB.
Sometimes used with computers other than PC.

Grzyb wrote on 2023-02-14, 15:04:

Myloch wrote on 2023-02-14, 14:44:

A 3.5" disk I won in an auction is 360k. Wait a moment, isn't this capacity supposed to be for 5.25" disks? 😮

3.5" Single Sided, Double Density is 360 KB.
Sometimes used with computers other than PC.

360KB also is the "forgotten" format that 3,5"1,44 MB drives can read/write. Including the modern USB floppy drives.

Back in time, 360KB format was used with 3,5" floppy drives on legacy hardware that didn't support anything higher than 360KB SD.
The 3,5" drive was used as a drop-in replacement, so to say.

It's a disk with shareware from germany, for PC. Since the floppy had a bad shape (mould and dirt) I thought it was unreadable for that reason, and it stayed on my desk for months. But apparently it was just that Windows 7 didn't recognize that and wanted me to reformat. I casually discovered all the data was intact when I tried to read it with a japanese imaging tool for floppies. I'm prone to think all windows versions (except maybe 95-98-me) cannot recognize 360k formatted 3.5" disks.

It's never been a standard format on the PC.
But of course, a Double Sided drive can read Single Sided media.

Another possibility for a 360 KB 3.5" diskette is Double Sided, Double Density, but with only 40 tracks written.
Once upon a time, I encountered such a disk, bundled with some hardware - two diskettes were provided, 5.25" and 3.5", both 360 KB, with exactly the same contents - obviously both created off the same disk image.

Myloch wrote on 2023-02-14, 15:36:

I casually discovered all the data was intact when I tried to read it with a japanese imaging tool for floppies.
I'm prone to think all windows versions (except maybe 95-98-me) cannot recognize 360k formatted 3.5" disks.

That's one of the many reasons I have a copy of WinImage 3 and Windows 3.1 on my vintage computers. 😁
Windows 3.1x doesn't do the IHC damage, also: https://www.os2museum.com/wp/the-ihc-damage/

Btw, didn't use the MSX computers such low-end floppy formats, too ?
If so, their community may have some expertise in this field.

Yes the MSX can have single-sided or double-sided 3.5" drives (depending on the machine). Those use the same format of MS-DOS (because MSX-DOS was derived from it).

Nice to know that 1,2MB drives can read all the lower capacities as well. Writing wouldn't be that important for me, since I imagine if I ever got my hands on any 360k floppies, they'd come filled with data already - so passive reading is good enough. Clean, new 1,2 MB floppies could be used for writing stuff to instead.

I just got a system to work that has core 2 duo and windows 10 but supports dual floppy including 5,25'' with no modifications, that's a pretty rare and specialized motherboard that I was able to find, pretty stoked about this 😁