INT 2F U - IOMEGA DRIVERS - LOCK MEDIA IN DRIVE                                 
	AX = 5711h
	BX = program ID??? (0201h used by GUEST.EXE)
	DX = 496Fh ('Io')
Return: CF clear if successful (storage medium in drive)
	    AX = new lock count
	CF set on error (drive empty)
SeeAlso: AX=5700h,AX=5701h,AX=5710h,AX=5712h