Path: utzoo!news-server.csri.toronto.edu!cs.utexas.edu!usc!jarthur!nntp-server.caltech.edu!pooh!madler
From: madler@pooh.caltech.edu (Mark Adler)
Newsgroups: comp.sys.next
Subject: Re: How to generate BREAK code?
Message-ID: <1991Mar11.023158.9529@nntp-server.caltech.edu>
Date: 11 Mar 91 02:31:58 GMT
References: <446@heaven.woodside.ca.us> <JBRYANS.91Mar5142822@beach.csulb.edu> <1991Mar10.115359.17943@thunder.mcrcim.mcgill.edu>
Sender: news@nntp-server.caltech.edu
Organization: California Institute of Technology, Pasadena
Lines: 17


der Mouse ponders:

>> (Hmmm.  I hope I haven't got SPACE and MARK interchanged....)

Yep, you got 'em backwards.  (I had to look it up to check.)

The resting state of an RS-232 (422, 423) line is MARK.  A start bit
is a SPACE.  A break is a very long SPACE.  Of course, this means little
without knowing what a MARK and SPACE are.  A MARK (the resting state) is
a negative voltage, and in the data, corresponds to a binary one.
A SPACE is a positive voltage, and corresponds to a binary zero.
Confused yet?  Also, for the control lines, a SPACE means that the
control is asserted, and a MARK means it ain't.

Mark (space) Adler
madler@pooh.caltech.edu