Date: Wed, 03 Sep 1997 17:36:51 +0930 From: Mike Smith <mike@smith.net.au> To: Greg Lehey <grog@lemis.com> Cc: Mike Smith <mike@smith.net.au>, FreeBSD Chat <chat@FreeBSD.ORG> Subject: Re: Anyway to get connect speed with usermode ppp/tun0 device? Message-ID: <199709030806.RAA00241@word.smith.net.au> In-Reply-To: Your message of "Wed, 03 Sep 1997 16:39:57 %2B0930." <19970903163957.09017@lemis.com>
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> (moved to chat) > > On Wed, Sep 03, 1997 at 04:29:44PM +0930, Mike Smith wrote: > >> > >>> The speed is specified as 'baud'; in fact, it's bit per second. > > > > It is correct to specify the speed as "baud" in conjunction with a > > single-wire serial interface. > > I suppose you mean a two-wire interface. No. A two wire interface can transport four values per baud. > Sure, you can use the term > baud if that's the speed talking about. Here we're talking about a > 2400 baud interface. It's transferring 38,400 bits per second. Not by any definition I can comprehend. You have a single wire serial interface, clocked at 38,400 transitions per second. That is 38,400 baud no matter which way you look at it. To achieve 38,400 bps at 2400 baud you need a signalling mechanism with 65536 possible values, or 16 bits of significance. This puts you in the high-end trellis-encoding market, certainly not on good ol' EIA-232. > OK, you might say "this interface is between the serial interface and > the modem". And yes, over this interface the speed is 38,400 baud as > well as 38,400 bps. But that's \fIvery\fP misleading, and there's no > need for it. I don't understand. stty can only report on the configuration of the serial port, and it does that correctly. It has no way of knowing what the modem thinks its doing; as I have already pointed out it is impossible to know what the modem is "really" doing at any point in time anyway. "Yes, I do know what 'baud' means." 8) mike
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