Subject: Re: High serial port (output) speeds
To: der Mouse <mouse@Rodents.Montreal.QC.CA>
From: Bill Studenmund <>
List: port-sparc
Date: 10/23/1999 18:23:09
On Sat, 23 Oct 1999, der Mouse wrote:

> > Both power and 68k macs use a 3.68 MHz receive clock (14400 * 256).
> > So from the BRG, the highest baud rate is 14400*256/16/4 = 57600.
> Only if you insist on using the BRG in divide-by-16 mode.  Use
> divide-by-1 instead and your max rate is 14400*256/4 = 921600, just as
> the SPARC's max rate in divide-by-1 mode is 1228800 (= 9600*512/4).

Right. My other message indicates why I "insist" on using 16x (or 32x)
mode. :-) 1x mode without synchronization will work a little, but will
fall over under load. :-)

I remember Jonathan experimented once with running sone pmax workstations
in 1x mode. It just didn't work reliably in his experience. I'm afraid the
same'd happen here.

Or actually what I'm more concerned about is that folks who didn't
understand what's wrong with 1x mode would try to use it, and then get mad
at NetBSD when it didn't work. :-)

Take care,