Technical information

Serial Solutions NewBIOS Reference
The following modes are currently supported:
Mode Use
0 RS232 standard, DTR/CTS
(this was the default)
1 RS422 RTS/CTS
2 RS485 half duplex handshake, RTS set true
during output.
3 RS485 send only, RTS always set true.
4 No handshake, also known as three handshake.
Only Txd, Rxd and Ground wires need be
connected. All other lines are ignored.
(This is now the default )
Chapter "What To Do First", section "Handshake
Selection" gives more details of the hardware handshakes.
Other Points.____________
NewBIOS will allow the setting of handshake modes for
ports whose address has not yet been set, but their address
remains zero and they cannot be used.
Page 96 Chapter 5