Using 1.44MB Floppies as 1.2MB Floppies [PC-98]

The PC-98 uses a weird 1.2MB 3.5“ disk format, that is almost, but not-quite compatible with traditional IBM PC 3.5” 1.44MB floppies (it can use the disks themselves, but cannot read the contents).

On Linux, to prepare a standard 3.5“ high density floppy as a PC-98 1.2MB floppy you need to install the tool ufiformat:

First install it from your standard package repo (it's in the Ubuntu/Mint repositories):

$ apt-get install ufiformat

Then insert a blank floppy in your internal/external/USB floppy drive and reformat it (where sdm is the device name of your floppy drive of course):

$ ufiformat /dev/sdm -f 1232

If you look at the output of dmesg now, you'll see that it has turned the format of the floppy itself into a 1.2MB disk:

[3034644.733661] sd 15:0:0:0: [sdm] 2880 512-byte logical blocks: (1.47 MB/1.41 MiB)
[3034714.697763] usb 1-1.5: reset full-speed USB device number 51 using ehci-pci
[3034715.039175] sd 15:0:0:0: Power-on or device reset occurred
[3034715.679181] sd 15:0:0:0: [sdm] Spinning up disk...
[3034716.841769] .
[3034718.249766] .
[3034718.495158] ready
[3034719.007182] sd 15:0:0:0: [sdm] 1232 1024-byte logical blocks: (1.26 MB/1.20 MiB)
[3034719.775155] sdm: detected capacity change from 0 to 1261568

You can now happily dd a PC-98 floppy image to the disk:

sudo dd if=MS-DOS\ 6.20\ \(System\ disk\ #1\).hdm of=/dev/sdm bs=64k status=progress
19+1 records in
19+1 records out
1261568 bytes (1.3 MB, 1.2 MiB) copied, 41.8561 s, 30.1 kB/s
  • blog/pc98_fdd.txt
  • Last modified: 2019/06/30 12:03
  • by john