3.5 inch floppies are not 720KB, 880KB or 1.44MB:
Double sided, double density: 1 megabyte in MFM format.
Double sided, high density: 2 megabytes in MFM format.
On the Amiga, you could actually store 1MB on a DD disk, because the disk drive controller can handle it.
All this assumes you only store the data on the disk, but formatting doesn't take up that much space of a floppy anyway (880KB Amiga file system still doesn't use the entire disk, same for peecee formats).
Last edited by Thorham; 07 April 2011 at 19:15.