Fdformat is the name of two unrelated programs, both performing "low-level format" of floppy disks.
It allows users to format a floppy to a higher than usual density, enabling the user to store up to 300 kilobytes more data on a normal high density 3.5" floppy disk.
It also increases the speed of diskette I/O on these specially formatted disks using a technique called "Sector Sliding".
The Linux fdformat program works with the kernel floppy driver.
[2] Functionality similar to Hochstätter's FDFORMAT is provided by fdutils, written by Alain Knaff.