JV> Best to use int 14 just to setup the [serial] ports, but
JV> deal with reading/writing them directly. Can't remember 
JV> exactly why, ...
  The usually undocumented feature of Int 14 serial port operation is
that the BIOS function uses the CTS/RTS lines (pins 5 or 8  AND pins 4
or 7 on 25 or 9 pin connectors).  Remember that the world is not binary, 
it is ternary. This means that the CTS/RTS lines can be logic 1, logic
0, or undefined.  On serial ports where these CTS/RTS lines are not
connected, the the Undefined state occurs often.  Therefore the serial
port works sometimes, then stops working other times.  
Many people become frustrated with the unexplained operation they
get from INT 14h (because they don't understand the CTS/RTS signals)
and end up writing their own code directly to the UART.
But the quick and dirty solution is quite simple.  Connect the CTS and
RTS lines from each UART to its corresponding neighbor.  INT 14h should 
take care of the rest.
--- Maximus 3.01
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