Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!sun-barr!cs.utexas.edu!uunet!van-bc!
From: lphillips@lpami.wimsey.bc.ca (Larry Phillips)
Newsgroups: comp.sys.amiga
Subject: Re:
Message-ID: <615@lpami.wimsey.bc.ca>
Date: 7 Jul 89 02:12:13 GMT
Lines: 38
To: van-bc!rnews

In <42403@bbn.COM>, denbeste@bbn.com (Steven Den Beste) writes:
>Part of why I'm confused is that EVERYONE seems to use "baudrate" informally to
>mean the rate at which the computer can feed bits to the modem. A "9600 baud"
>modem always is reported to carry 960 10-bit characters per second - even if it
>is only making 2400 transitions per second on the telephone line.

Well, that is the problem in a nutshell. Common usage is not technically
correct. If modems were measured by the baud rate on the computer side, the bps
and baud would be the same.

The signalling rate vs. bits/second rate look like this on each side of the
modem:


      2400 bps            2400 bps

CPU ------------- MODEM ------------- PHONE LINE

      2400 baud            600 baud


The reason for this is that on the CPU side of the modem, one transition (state
change) represents one bit, while on the phone side, 1 state change represents
4 bits. Common usage says we have a 2400 'baud' modem here, while engineers
would call it a 2400 'bps' modem running at 4 bits per baud.

Not that this will make a lot of difference, since the general public will
still call them 2400 baud modems, and we will all know what is meant by that.

-larry

--
Van Roy's Law:  An unbreakable toy is useful for breaking other toys.
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|   //   Larry Phillips                                                |
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|        COMPUSERVE: 76703,4322                                        |
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