From owner-freebsd-hackers  Fri Aug 25 10:28:00 1995
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From: terry@cs.weber.edu (Terry Lambert)
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Subject: Re: ISDN Anyone?
To: jkh@time.cdrom.com (Jordan K. Hubbard)
Date: Fri, 25 Aug 95 11:28:02 MDT
Cc: phk@critter.tfs.com, phk@freefall.FreeBSD.org,
        jgreco@brasil.moneng.mei.com, terryl@CS.Stanford.EDU,
        freebsd-hackers@freebsd.org
In-Reply-To: <20546.809317604@time.cdrom.com> from "Jordan K. Hubbard" at Aug 24, 95 07:26:44 pm
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> > There is actually a lot more promise in a 16550 or 16650 at 460800 bps.
> > You only get 1/16th or 1/32th the number of interrupts.
> 
> Hmmm.  I find that the serial interrupt overhead is pretty intense at 115.2
> even with a 16550.  You know some secret for doing this I don't?

That's because it's being done wrong.

You take the interrupt and poll like hell in the service routine to handle
higher data rates.  You can do 115k on a non-FIFO'ed UART using this
technique.


					Terry Lambert
					terry@cs.weber.edu
---
Any opinions in this posting are my own and not those of my present
or previous employers.