I beleive the uarts still default to FIFOs disabled. I use rs422 on plan9 (on a 1.6Ghz machine) at 115Kbaud reliably - as long as the fifo is enabled (the manpage is a bit out of date, though the source isn't). Having said this I _do_ have trouble at 115K on my 400Mhz laptop, which is sad as it could be really useful.
Updating the manpage moves one click up the To-do list... -Steve
