INT 2F U - DOS 5.0+ SETUP
AH = 49h
AL = function
00h update format completion gauge
BX = percentage complete, 0000h when done, FFFFh if aborted
Return: AX = status
0000h continue formatting
else installation program wants FORMAT to abort
10h get pointer to resident data
AX = FFFFh if supported
ES:BX -> internal structure
???
Return: ???