P.S. the big secret is that you can't run pure ASCII with no other
protocol and pull this off. All of the devices have to know when to
talk, and when to shut up.
On 1/5/2015 9:34 PM, Lynn W. Taylor, WB6UUT wrote:
Don,
In the relatively early days of Packet Radio there were more than a
few multi-port NET-ROM nodes that were assembled by tying three (or
more) TNC-2s together with a relatively simple diode combiner.
I may even still have the diagram for combiner. It wasn't powered,
didn't have anything more complex than diodes.
The TNC-2 used normal 1488/1489 chips for receivers and drivers, and
took slight advantage of the fact that the receiver didn't strictly
"need" RS-232 levels (that 0v was as good as -3v).
Serial errors did occur when two or more ports tried to talk at once,
but NET-ROM ran AX-25 on the serial port and the errors got handled
that way.
73 -- Lynn
On 1/5/2015 8:59 PM, Don Wilhelm wrote:
Since RS-232 is a point-to-point protocol, multiple TX drivers cannot
exist together.
\
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