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From: preece@uicsl.UUCP
Newsgroups: net.micro
Subject: Re: 1200 baud modem problems - (nf)
Message-ID: <4958@uiucdcs.UUCP>
Date: Wed, 18-Jan-84 22:45:19 EST
Article-I.D.: uiucdcs.4958
Posted: Wed Jan 18 22:45:19 1984
Date-Received: Sat, 21-Jan-84 06:58:15 EST
Lines: 22

#R:sri-arpa:-1540200:uicsl:7000040:000:1035
uicsl!preece    Jan 18 12:59:00 1984

I'm a little confused by claims that the ability/inability to send
a break lies in the terminal program and not in the modem. The
terminal program must, indeed, do something to tell the modem to
send a break. The modem itself, however, is the only place that
the break state can be induced on the line, so it too must have a
special ability. The terminal sets the data line (between itself
and the modem) to the space state for a relatively long time (say
a quarter of a second). The modem must recognize that that is a
signal to it to pass on a (relatively) long space state. Aa 212A
modem doesn't just use the data line state to select between two
signals it can send down the line. Among other things, it uses a
four-level signal, so two states are sent at once.  I suspect the
modem gathers a whole character before sending anything, but I
am just guessing. I have read in several places that the Anchor
212 modem cannot send a break; that doesn't make it true, but it
makes me suspicious.

scott preece
ihnp4!uiucdcs!uicsl!preece