A 1.44 “MB” floppy is 1440k, or about 1.406 real MB, and of that the space used by the FAT file system reduces it to around 1.38 free space.
For some reason I couldn’t find the exact number and don’t have any handy to check it myself.
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.
Very little, around 60k.
A 1.44 “MB” floppy is 1440k, or about 1.406 real MB, and of that the space used by the FAT file system reduces it to around 1.38 free space.
For some reason I couldn’t find the exact number and don’t have any handy to check it myself.
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 EntriesIf 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.