INT 2A - NETWORK (Microsoft,LANtastic) - EXECUTE NetBIOS REQUEST
        AH = 04h
        AL = error retry
            00h automatically retry request on errors 09h, 12h, and 21h
            01h no retry
            02h ???
        ES:BX -> Network Control Block (see INT 5C"NetBIOS")
Return: AX = 0000h if successful
        AH = 01h on error
            AL = error code
Notes:  invokes either INT 5B or INT 5C as appropriate
        also supported by Lantastic, NetWare, 10NET, etc.
        NetWare 2.15 NetBIOS emulator returns CF clear if successful, CF set
          on error
SeeAlso: AH=01h,AX=0500h,INT 5B,INT 5C"NetBIOS"

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