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From: hughes@locusts.Berkeley.EDU (Eric Hughes)
Newsgroups: comp.os.msdos.programmer
Subject: Re: Modems and baud rate divisors
Message-ID: <HUGHES.90Dec1153716@locusts.Berkeley.EDU>
Date: 1 Dec 90 23:37:15 GMT
References: <2128@mentor.cc.purdue.edu>
Sender: usenet@agate.berkeley.edu (USENET Administrator)
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In-Reply-To: standish@mentor.cc.purdue.edu's message of 1 Dec 90 22:12:33 GMT

In article <2128@mentor.cc.purdue.edu> standish@mentor.cc.purdue.edu
(Dreamwalker) writes:
>Could someone tell me what the baud rate divisors are for a modem?

You are really programming the serial port chip, not the modem.

>All I have is that 300 baud is 384, ...

A baud rate divisor takes an external clock and divides it down to
get lower frequencies.

Thus if 300 bps corresponds to 384, then 1200 bps corresponds to
384/4 = 96, 2400 bps --> 48, 9600 bps --> 24, and 115200 bps --> 1.

This is where that 115 Kbps figure for fast serial port connections
from PC to PC comes from.

Eric Hughes
hughes@ocf.berkeley.edu