*BSD News Article 18444


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Newsgroups: comp.os.386bsd.questions
Path: sserve!newshost.anu.edu.au!munnari.oz.au!news.Hawaii.Edu!ames!haven.umd.edu!uunet!Germany.EU.net!mcsun!ieunet!ieunet!dec4ie.ieunet.ie!jkh
From: jkh@whisker.lotus.ie (Jordan K. Hubbard)
Subject: Re: what is sio?
In-Reply-To: jbw@bbin.uucp's message of 15 Jul 93 00: 05:58 GMT
Message-ID: <JKH.93Jul15082332@whisker.lotus.ie>
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Organization: Lotus Development Ireland
References: <RAM.93Jul10194417@xor.epi.wisc.edu>
	<1993Jul12.075521.13223@cnplss5.cnps.philips.nl> <CA6Iy2.Bsu@bbin.uucp>
Date: Thu, 15 Jul 1993 08:23:32 GMT
Lines: 15

>What does it mean for the serial driver to be bidirectional?  I would have
>thought they all would be able to send and recieve data so it must mean
>something else?

It means you can dial both in and out on the same line (think about it
- if a getty is always sitting on a normal "unidirectional" port, you
can never open it for outgoing read/write.  Likewise, if you always
use it for going out with tip or kermit, then the lack of a getty will
mean that no one can log in on it.  The bidir hacks allow this by
putting the getty to sleep when it's not needed (that's the simplest
way to look at it, anyway).

				Jordan
--
Jordan Hubbard  jkh@violet.berkeley.edu, jkh@al.org, jkh@whisker.lotus.ie