> Data is getting garbled between my TNC and PC, when running at anything
> over 4800 baud. The TNC appears to work fine with another PC, so I am
> lift with the conclusion it is my PC at fault, although I have tried
> using another serial board with the same result.
Does your serial card use a 16550A UART or a 16450? The 16550 includes a
FIFO buffer which helps a lot when trying to use your serial port at higher
speeds. If you can find/try a 16550[AFN] UART that may well be enough
to enable you to move up in speed.
Terry