On Sat, 6 Sep 2003, Rich Beaudry wrote: If you upgrade to DOS 3.20 or newer, then you do NOT need that disk. If your XT has IBM's BIOS, then you need to add DRIVER.SYS to your CONFIG.SYS file. If you are using a non-IBM BIOS, then you can use DRIVPARM instead (in MS-DOS, and present but not documented in PC-DOS) NOTE: DRIVPARM is incompatible with IBM's BIOS. If you want to use DOS <3.20, then you want that disk. NOTE: SOME versions of MS-DOS 2.11 support 720K.