INT 6F - 10-NET - RECEIVE
        AH = 05h
        CX = number of seconds before timeout
        DS:DX -> receive buffer (see below)
Return: CF set on error
            AX = error code (see AH=00h)
        CF clear if successful
            AH = FEh if dequeued message is a CB message

Format of receive buffer:
Offset  Size    Description
 00h 12 BYTEs   sending node's ID
 0Ch    WORD    length of message
 0Eh  N BYTEs   message (maximum 1024 bytes)