Int 62 Fn 0B  - Cswitch - Send Message                                     [T]

   AH = 0Bh
   CX = number of bytes to write
   DS:SI -> buffer
   DX = queue number (0-63)

Return: AX = FFFEh triggered by something arriving, redo the call
      = FFFFh bad queue number
      = 0000h no message was on queue
        else  number of bytes in message

See Also: AH=0Ah,AH=0Ch