INT 6B - Novell NASI/NACS, Ungermann-Bass Net One SERIAL I/O - BUFFERED WRITE
        AX = 0000h
        CX = length
        ES:BX -> buffer
Return: CX = number of bytes written
Program: NASI is Novell's NetWare Asynchronous Services Interface which runs
          on workstations; NACS is the NetWare Asynchronous Communications
          Services module which runs on servers
Notes:  this function is also supported by TelAPI and NPC NCSI; for TelAPI,
          nonzero values in AL specify a connection ID
        this function is also supported by Connection Manager CLIENT.EXE; it
          provides the signature string "NCSI" three bytes past the interrupt
          handler, and returns CF set/AL=FFh if called while an INT 6B call is
          already in progress
SeeAlso: AX=0100h,AH=18h,INT 14/AH=19h,INT 14/AH=E3h

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