*BSD News Article 10367


Return to BSD News archive

Received: by minnie.vk1xwt.ampr.org with NNTP
	id AA7834 ; Tue, 26 Jan 93 19:00:21 EST
Newsgroups: comp.unix.bsd
Path: sserve!manuel.anu.edu.au!munnari.oz.au!spool.mu.edu!uunet!boulder!ucsu!rintintin.Colorado.EDU!galbrait
From: galbrait@rintintin.Colorado.EDU (GALBRAITH JOHN)
Subject: Re: reading from parallel port
Message-ID: <1993Jan26.025455.7032@ucsu.Colorado.EDU>
Sender: news@ucsu.Colorado.EDU (USENET News System)
Nntp-Posting-Host: rintintin.colorado.edu
Organization: University of Colorado, Boulder
References: <1jhejv$9l3@Germany.EU.net> <C1ADIM.1s3@sleeper.apana.org.au>
Date: Tue, 26 Jan 1993 02:54:55 GMT
Lines: 29

In article <C1ADIM.1s3@sleeper.apana.org.au> raz@sleeper.apana.org.au (Roland Turner) writes:
>bs@Germany.EU.net (Bernard Steiner) writes:
>
>>Folks,
>>I just read through one of those terrible x86 magazines. Somebody advertized
>>their LPT port ethernet[TM] adapter.
>
>>While I believe that the idea of driving the ethernet through a slow LPT
>>port is not really fascinating, I sort of like the idea of using the
>>parallel port for "serious work". This would require reading from the
>>port, though.
>

I have built some hardware that read from the parallel port.  The problem
is that the main data lines are output only.  You can read from the port,
but it returns the last value that you wrote, not what is currently
what you may have put on the port.
	I did get it to work (I was building a MIDI port for a lab).  What
I did was to use four control lines from one of the ports that CAN be read
and read a nibble at a time.  It worked, and was fine for MIDI (A serial
interface) but I would imagine that it would be SLOW for an ethernet card.

Also, it could be that some newer lpt cards do have bidirectionality.  I
think the MCA cards do for instance, but I may be wrong.

john galbraith
galbrait@rintintin.colorado.edu