Asklemmy

The floppy disk format is based on the FAT12 file system.

https://www.cs.drexel.edu/~johnsojr/2012-13/fall/cs370/resources/UnderstandingFAT12.pdf

And with enough creative tweaks to that file system, you can get DMF 1.68MB format, and if you think a bit outside the box and erase the redundant secondary FAT table and settle on a max of only 16 files on the disk, you can squeeze a few more kilobytes out of that even.

I actually made a number of custom modded blank disk images with more storage space, I might dig out the full specs of all the variants later.

Modified versions of various blank floppies
-------------------------------------------
These modifications reduce the number of
FAT tables from 2 to 1 and also reduce the
number of root entries down to 16 files,
which frees up some extra storage space.

The 1.72MB format can ONLY be used on Win9X
systems on real hardware, as not even WinNT
can access tracks 81 or 82 on floppy disks.
Disk image programs like WinImage can still
access files within 1.72MB floppy images.



1.44MB Standard:
80 Tracks		18 Sectors/Track
2880 Sectors Total	1474560 Bytes Total
-------------------------------------------
Sectors Per Cluster: 1	Number of FATs: 2
Max Root Entries: 224	Sectors Per FAT: 9
1457664 Bytes Data

1.44MB Maxed:
-------------------------------------------
Sectors Per Cluster: 4	Number of FATs: 1
Max Root Entries: 64	Sectors Per FAT: 3
1470464 Bytes Data

Differences:
-------------------------------------------
12800 Bytes More, 160 Less Root Entries



1.68MB Standard:
80 Tracks		21 Sectors/Track
3360 Sectors Total	1720320 Bytes Total
-------------------------------------------
Sectors Per Cluster: 1	Number of FATs: 2
Max Root Entries: 224	Sectors Per FAT: 10
1702400 Bytes Data

1.68MB Maxed:
-------------------------------------------
Sectors Per Cluster: 4	Number of FATs: 1
Max Root Entries: 64	Sectors Per FAT: 3
1716224 Bytes Data

Differences:
-------------------------------------------
13824 Bytes More, 160 Less Root Entries



DMF 1024 Standard:
80 Tracks		21 Sectors/Track
3360 Sectors Total	1720320 Bytes Total
-------------------------------------------
Sectors Per Cluster: 2	Number of FATs: 2
Max Root Entries: 16	Sectors Per FAT: 5
1714176 Bytes Data

DMF 1024 Maxed:
-------------------------------------------
Sectors Per Cluster: 4	Number of FATs: 1
Max Root Entries: 64	Sectors Per FAT: 3
1716224 Bytes Data

2048 Bytes More, 48 More Root Entries



DMF 2048 Standard:
80 Tracks		21 Sectors/Track
3360 Sectors Total	1720320 Bytes Total
-------------------------------------------
Sectors Per Cluster: 4	Number of FATs: 2
Max Root Entries: 16	Sectors Per FAT: 3
1716224 Bytes Data

DMF 2048 Maxed:
-------------------------------------------
Sectors Per Cluster: 4	Number of FATs: 1
Max Root Entries: 64	Sectors Per FAT: 3
1716224 Bytes Data

Differences:
-------------------------------------------
0 Bytes More, 48 More Root Entries



1.72MB Standard:
82 Tracks		21 Sectors/Track
3444 Sectors Total	1763328 Bytes Total
-------------------------------------------
Sectors Per Cluster: 1	Number of FATs: 2
Max Root Entries: 224	Sectors Per FAT: 10
1745408 Bytes Data

1.72MB Maxed:
-------------------------------------------
Sectors Per Cluster: 4	Number of FATs: 1
Max Root Entries: 64	Sectors Per FAT: 3
1759232 Bytes Data

Differences:
-------------------------------------------
13824 Bytes More, 160 Less Root Entries

If you're interested in the blank disk images themselves, let me know.

Also, 1474560 / 1024 = 1440

If anyone could keep up with binary numbers back in the day, floppy disks were literally measured in binary megabytes.