INT 7F - Alloy NTNX, MW386 - ATTACH OR RELEASE DRIVE FOR LOW-LEVEL WRITE ACCESS
        AH = 24h
        CL = function
            00h attach
            01h release
        CH = drive (0=A:,1=B:,etc)
Return: AX = status
            00h successful
            01h invalid request
            02h already attached
            03h not attached
            04h lock table full
Note:   only drives on the current machine may be attached