Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!usc!ucsd!ucbvax!bloom-beacon!eru!hagbard!sunic!news.funet.fi!ousrvr!ousrvr!so-hpa From: so-hpa@stekt.oulu.fi (Heikki Paananen) Newsgroups: comp.sources.wanted Subject: Re: (something about PRN) Message-ID: Date: 7 Nov 90 14:01:31 GMT Sender: news@ousrvr.oulu.fi Distribution: comp Organization: University of Oulu, Dept. of EE, Finland Lines: 28 I say, joep@tnosoes.izf.tno.nl was wondering if there is some way to put two MSDOS machines communicating via PRN port. As far as I know the PRN port is unidirectional (that is, there is usually 8-bit latch (74LS373 or similar located on the paraller port board which interfaces the fast processor for the slow printer). So, if someone is trying to push "highs" and "lows" into the port from the wrong direction (s)he would sooner or later end up with black thick cloud of smoke coming out from the cabinet. I think the only way to communicate via this port is employing the few input lines of the port. For example, there is a pin called OUT OF PAPER, which indicates that the printer has no paper. Now connecting one of the outputs to the out of paper -input of the second computer (and vice versa) and you will get a nice asyncronous 1-bit communication bus (but before that investigate the function of your COM port and you will find some similarities.) Yet, all this is true in my case and I am not sure that this information is universially valid (bidirectional latches or ...) If I am totally wrong, please inform me (got then someting to tell grandchildren too.) ------------------------------------------------------------------ There he sits, drawing images on the causeway ------------------------------------------------------------------ Heikki Paananen so-hpa@stekt.oulu.fi The university of Oulu Department of electrical engineering, FINLAND ------------------------------------------------------------------ With small bits of chalk he sketches all the lost days ------------------------------------------------------------------