Int 7C Fn 0009  - Sk-upps Data Link Interface API - Register Multicast     [N]

   AX = 0009h
   BX = protocol ID (see AX=0007h)
   ES:DI -> multicast address (6 bytes)

Return: AX = completion code (see AX=0001h)

Notes: The broadcast address is always enabled.
   Set bit 9 of PCB's protocol mode field in REGISTER PROTOCOL call
     (AX=0007h) to receive all multicast frames.

See Also: AX=000Ah,AX=0014h