In the case of Copy-Lock, Sector 1 on track 6 was intentionally written as only 256 bytes ... you can’t create this disk structure with a standard IBM PC floppy disk controller; you need ...

See Zip disk and Floptical. (2) An earlier 3.5" floppy disk developed by IBM and available on certain IBM PCs. With a 2.88MB capacity, the Extra High Density (ED) floppy drives were compatible ...