Subject: Re: serial line speeds...
To: Michael L. VanLoon -- HeadCandy.com <michaelv@MindBender.serv.net>
From: Feico Dillema <dillema@acm.org>
List: current-users
Date: 12/13/1997 21:22:07
Your message dated: Fri, 12 Dec 97 00:34:00 PST
>
>>Somewhere in the include files I found 230400 Bps as a standard terminal
>>speed, it is however not accepted by stty or pppd. I noticed that the speed
>>in termios.h is represented with an unsigned int value. Does this mean max.
>>serial speed is 65565 Bps??? If so, I find it a bit strange that 115200 Bps
>>is accepted just fine, while 230400 is not... I'm just being curious here.
>>Could somebody enlighted me on this topic? I may be a bit naive on these
>>things... Would it be a lot of work (and/or generate a lot of problems) to
>>switch from integer to long to support the fast serial lines (thinking of
>>ISDN-modems attached to serial ports here and such).
>
>I can't answer your question about internal representations of serial
>speeds.
Apologies for the stupid mistake. int is of course 32 bits (even on my
486 ;). I guess trying to save a system from a faulty disk the night
before gave me some lack of sleep and lack of active braincells the
next day...
>FWIW, the Hayes ESP cards, which also have a 1024-byte FIFO (and
>emulate a 16550 otherwise), claim to support up to 8 x 115200. You do
>this by running the DOS config utility and telling it to set a
>multiplier anywhere from 1x to 8x. Of course, 230400 could be
>achieved by setting the multiplier to 2x and telling NetBSD the port
>was 115200.
I guess it must be something like that. The question originated from
a friend of mine whose laptop is supposed to be able to do such
8x115200 speeds according to its system manual. That made me a
bit curious...
Thanks for all your replies,
Feico.