INT 61 - Banyan VINES - "Sorec" - RECEIVE INPUT EVENT NOTIFICATION
        AX = 0001h
        DS:DX -> communications control block (function 0003h)
Return: AX = status
            0000h  successful
            0001h  service not installed
            0002h  invalid service ID
            0003h-000Ah reserved for BANV interface errors
            0097h  invalid socket identifier
            00A2h  no more buffer space
            00A3h  timeout
Note:   BANYAN can use any interrupt from 60h through 66h.  The Banyan
          interrupt handler is identified by the string "BANV" in the four
          bytes immediately preceding the interrupt handler

Format of control block:
Offset  Size    Description
 00h    WORD    0003h
 02h    WORD    pointer to argument block (see below)
 04h    WORD    error return code
                0000h successful
                0097h invalid socket ID
                00A2h no more buffer space
                00A3h timeout event
                00A5h resource not available
                00A6h internal communication failure
                00B1h resource disconnect
 06h  4 BYTEs   reserved

Format of argument block:
Offset  Size    Description
 00h    WORD    character count
 02h    WORD    error return code
 04h    WORD    socket identifier
 06h    WORD    pointer to receive buffer
 08h    WORD    length of receive buffer
 0Ah    WORD    flags
                bit 0: async request
                    2: flush receive buffer on overflow
                    3: end of user message received
                    4: vectored request (if set, receive buffer contains buffer
                        descriptors)
                    5: connection-specific receive
                    6: change to connection-specific receive mode
 0Ch 16 BYTEs   socket address
 1Ch    WORD    timeout value in multiples of 200ms
 1Eh    WORD    connection identifier
 20h    WORD    type of response
                0001h message received
                0002h virtual connection established
                0003h virtual connection terminated

Format of buffer descriptor:
Offset  Size    Description
 00h    WORD    data segment
 02h    WORD    buffer pointer
 04h    WORD    buffer length
 06h    WORD    character count