INT 21 - Novell NetWare - WORKSTATION - GET PRIMARY CONNECTION ID
        AX = F005h
Return: AL = connection ID of primary file server (1-8), 00h if not set
Notes:  this function is supported by Advanced NetWare 2.0+
        by default, the primary file server is the one from which the login
          script executed; it is set to 00h if the workstation is not logged in
          and when it detaches from its primary file server
SeeAlso: AX=EF03h,AX=F000h,AX=F002h,AX=F004h