INT 2F U - IOMEGA DRIVERS - UNLOCK MEDIA IN DRIVE / EJECT                       
	AX = 5712h
	BX = program ID??? (0201h used by GUEST.EXE)
	DX = 496Fh ('Io')
Return: AX = new lock count (00h = unlocked)
Note:	if the lock count was already zero, the storage medium is ejected
	  from the drive
SeeAlso: AX=5700h,AX=5701h,AX=5710h,AX=5711h