INT 61 - Banyan VINES - "Sosession" - REGISTER APPLICATION WITH COMM SERVICE
        AX = 0001h
        DS:DX -> communications control block (function 0008h)
Return: AX = status
            0000h  successful
            00A2h  no more buffer space available
Note:   BANYAN can use any interrupt from 60h through 66h (default 61h).  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    0008h
 02h    WORD    process type
                0001h transient process
                0002h resident process
 04h    WORD    error return code
 06h  4 BYTEs   reserved