Int 7A  - Novell Netware - Spx Driver - Establish Spx Connection           [N]

   BX = 0011h
   AL = retry count
   AH = watchdog flag
   ES:SI -> Event Control Block (see BX=0003h)

Return: AL = status
       00h attempting to contact destination socket
       EFh local connection table full
       FDh buffer size not 42 or fragment count not 1
       FFh sending socket not open
   DX = assigned connection ID number
Desc:  attempt to establish a connection with a listening socket

Notes: there should always be at least two SPX ECB's listening to a socket, so
     that NetWare can perform its internal packet exchanges
   the first fragment should start with a SPX header.  Fill in all
     destination addresses.
   this function is supported by Advanced NetWare 2.1+

See Also: BX=0000h,BX=0012h,BX=0013h,BX=0014h,BX=0015h

Format of SPX header:
Offset Size    Description
 00h   WORD    (big-endian) checksum
 02h   WORD    (big-endian) length in bytes of total packet
 04h   BYTE    transport control
 05h   BYTE    packet type (see INT 7A/BX=0003h)
 06h 10 BYTEs  destination internet address
 10h   WORD    (big-endian) destination socket
 12h 10 BYTEs  source internet address
 1Ch   WORD    (big-endian) source socket
 1Eh   BYTE    connection control (see below)
 1Fh   BYTE    datastream type
       FEh terminate connection request packet
       FFh terminate connection acknowledgement packet
       other user-defined, ignored by SPX
 20h   WORD    (big-endian) source connection ID
 22h   WORD    (big-endian) destination connection ID
 24h   WORD    (big-endian) sequence number
 26h   WORD    (big-endian) acknowledge number
 28h   WORD    (big-endian) allocation number

Bitfield for connection control:
 bits 3-0 unused???
 bit 4 end of message
 bit 5 reserved
 bit 6 acknowledgement required
 bit 7 system packet