INT 2F U - DOS v5.0 - SINGLE-FLOPPY LOGICAL DRIVE CHANGE NOTIFICATION
AX = 4A00h
CX = 0000h
DH = new drive number
DL = current drive number
Return: CX = FFFFh to skip "Insert diskette for drive X:" message
Note:   called by MSDOS 5.00 IO.SYS just before displaying the message
"Insert diskette for drive X:" on single-floppy systems


2F4A00CX0000 - DOS v5.0 - SINGLE-FLOPPY LOGICAL DRIVE CHANGE NOTIFICATION