Slow Throughput with TB+ Modem
Eric S. Raymond
eric at snark.UUCP
Sun Dec 25 15:45:01 AEST 1988
In article <672 at vector.uucp>, chip at vector.UUCP (Chip Rosenthal) writes:
> In article <1439 at neoucom.UUCP> wtm at neoucom.UUCP (Bill Mayhew) writes:
> >I've been surprised at the gernally crummy serial port performance
> >of most IBM/Intel clone architecture machines exhibit. Even AT
> >class machines with the 16450s don't do very well at speeds greater
> >than 4800 bps.
>
> Correction -- even 386 class machines can't do it.
> When I was using a standard, dumb serial port on the XENIX box, I could
> never run faster than 4800bps. Even then it would drop characters if the
> system was heavily loaded. (I looked at the PC BIOS, and it looks like
> hardware flow control is supported, but I only have a 3-wire connection.
> XON/XOFF flow control is not supported.)
I run a 9600bps line to a 'blazer off a 16MHz 386 box using a generic dumb
serial card. It works like a champ. This is under stock Microport 3.0e, using
RTS/CTS flow control. I conjecture that either a) XENIX's serial-port driver is
brain-damaged (thresholds set wrong maybe, or too little c-list space) , or b)
your serial card really sucked. The latter seems marginally more likely.
--
Eric S. Raymond (the mad mastermind of TMN-Netnews)
Email: eric at snark.uu.net CompuServe: [72037,2306]
Post: 22 S. Warren Avenue, Malvern, PA 19355 Phone: (215)-296-5718
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