6 ms·

Wasn't there a way for Linux to format 3 1/4 inch floppy disks beyond the standard 1.44MB all the way to 2MB? Or was that simply using a compressed filesystem?

LeoPanthera 6y ago
Many of the "extra large floppy" tricks don't work with USB floppy drives, and require a "real" drive.
dragonwriter 6y ago
A “1.44MB floppy” referred to it's standard, IIRC, FAT formatted capacity; it actually had a 2MB total capacity.
- userbinator 6y ago
  Yes, the ultimate (unformatted) capacity of the medium is rougly 2 million bytes, and includes the sector headers as well as the gaps to account for rotational speed variance. The calculation is as follows: A 1.44M drive nominally writes at 500Kbit/s and spins at 300RPM, i.e. one track takes 200ms and 100Kbit are written. There are 80 tracks so 8000Kbit on one side, or 16000Kbit on two sides, corresponding to 2Mbit in total. By writing "long sectors" that take up the whole track, omitting almost all the overhead and gaps, and using up to 82 tracks, the 2M utility I linked in another comment here manages to reach very close to that limit.
  - VLM 6y ago
    In the 90s there used to be a web page for linux describing all the possible physical formats and one interesting side effect was changes in average kilobytes/sec transfer rate. Obviously more tracks simply took longer to read more data in a linear fashion but there were weird interactions where long sectors increased average bandwidth, mostly. I'm old enough to manually set interleave parameters on hard disks in the early 80s, so that was interesting. I don't remember interleave optimizing on floppies but I may just forget.
nitrogen 6y ago
I seem to recall the Windows 95 or 98 install floppies being 1.68MB each, but you could go further. If I remember right this involved either reducing redundancy in the FAT or increasing cluster size. Looks like this came up on HN before: https://news.ycombinator.com/item?id=19583531 https://news.ycombinator.com/item?id=19583531
- dspillett 6y ago
  While they did tweak things like the number of root entries and such, the main way to get more space was simple to cram more sectors onto each track than the standard format (and make sure they weren't using cheap floppies that couldn't work correctly with the extra data density). Some cheap/grotty/dying floppy drives were not happy either the extra data density either, though that was a rare problem (anecdata: I experienced one drive that didn't like the format but would read everything else I expected it to).
userbinator 6y ago
https://en.wikipedia.org/wiki/2M_(DOS) https://en.wikipedia.org/wiki/2M_(DOS)
abbeyj 6y ago
https://en.wikipedia.org/wiki/Distribution_Media_Format https://en.wikipedia.org/wiki/Distribution_Media_Format
edent 6y ago
I did look at that, but I couldn't quickly find a way to get the Pi to read them.
walrus01 6y ago
There was also an official standard for 2.88MB floppy disks which never caught on much, and by the time it would have been useful the zip disk, ls100 and CD-R drives killed it. Finding media for it now would probably be difficult and costly. The floppy drive seen in the adapter with the small ribbon cable is the same from x86 PC laptops around 2002. I don't think any slimline type 2.88MB drives were made, only desktop size.

LeoPanthera 6y ago

Many of the "extra large floppy" tricks don't work with USB floppy drives, and require a "real" drive.

dragonwriter 6y ago

A “1.44MB floppy” referred to it's standard, IIRC, FAT formatted capacity; it actually had a 2MB total capacity.

userbinator 6y ago
Yes, the ultimate (unformatted) capacity of the medium is rougly 2 million bytes, and includes the sector headers as well as the gaps to account for rotational speed variance. The calculation is as follows: A 1.44M drive nominally writes at 500Kbit/s and spins at 300RPM, i.e. one track takes 200ms and 100Kbit are written. There are 80 tracks so 8000Kbit on one side, or 16000Kbit on two sides, corresponding to 2Mbit in total. By writing "long sectors" that take up the whole track, omitting almost all the overhead and gaps, and using up to 82 tracks, the 2M utility I linked in another comment here manages to reach very close to that limit.
- VLM 6y ago
  In the 90s there used to be a web page for linux describing all the possible physical formats and one interesting side effect was changes in average kilobytes/sec transfer rate. Obviously more tracks simply took longer to read more data in a linear fashion but there were weird interactions where long sectors increased average bandwidth, mostly. I'm old enough to manually set interleave parameters on hard disks in the early 80s, so that was interesting. I don't remember interleave optimizing on floppies but I may just forget.

nitrogen 6y ago

I seem to recall the Windows 95 or 98 install floppies being 1.68MB each, but you could go further. If I remember right this involved either reducing redundancy in the FAT or increasing cluster size. Looks like this came up on HN before: https://news.ycombinator.com/item?id=19583531 https://news.ycombinator.com/item?id=19583531

dspillett 6y ago
While they did tweak things like the number of root entries and such, the main way to get more space was simple to cram more sectors onto each track than the standard format (and make sure they weren't using cheap floppies that couldn't work correctly with the extra data density). Some cheap/grotty/dying floppy drives were not happy either the extra data density either, though that was a rare problem (anecdata: I experienced one drive that didn't like the format but would read everything else I expected it to).

userbinator 6y ago

https://en.wikipedia.org/wiki/2M_(DOS) https://en.wikipedia.org/wiki/2M_(DOS)

abbeyj 6y ago

https://en.wikipedia.org/wiki/Distribution_Media_Format https://en.wikipedia.org/wiki/Distribution_Media_Format

edent 6y ago

I did look at that, but I couldn't quickly find a way to get the Pi to read them.

walrus01 6y ago

There was also an official standard for 2.88MB floppy disks which never caught on much, and by the time it would have been useful the zip disk, ls100 and CD-R drives killed it. Finding media for it now would probably be difficult and costly. The floppy drive seen in the adapter with the small ribbon cable is the same from x86 PC laptops around 2002. I don't think any slimline type 2.88MB drives were made, only desktop size.