Path: utzoo!attcan!uunet!mcvax!unido!sbsvax!fs-info
From: fs-info@sbsvax.UUCP (Fachschaft Mathe/Info)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Bidirectional use of parallel port
Summary: Sometimes it can be done...
Message-ID: <708@sbsvax.UUCP>
Date: 20 Mar 89 14:52:15 GMT
References: <441@harrier.ukc.ac.uk>
Organization: Universitaet des Saarlandes, Saarbruecken, W-Germany
Lines: 28

In article <441@harrier.ukc.ac.uk>, rde@ukc.ac.uk (R.D.Eager) writes:
> 
> I see reviews of various products for fast transfer of files between PCs
> using the parallel port. My question is: how do they do this? The PC parallel
> port is inherently unidirectional, so are they just using the status lines
> for transferring data? I would like to know...I have an application where
> I want bidirectional transfer like this.

The original PC parallel port had been unidirectional, but fortunately not
everybody accepts everything comin' from IBM. Many parallel ports found on
graphic cards ARE bidirectional. Others are not.
Some time ago i ran into this problem. I wrote a program on my machine that
took the parallel port to be bidirectional, and everything worked fine.
Then the thing was brought to the dedicated machine, and everything went wrong.
But there i found 4 good usable status lines, and with the 8 data pins as a 
multiplex selection it worked again.
So, U see, old murphy now takes the parallel port domain, too :
Every parallel port is bidirectional, unless it needs to be

  
Patrick SCHAAF, you reach me as :

Fachschaft Mathe/Info              
Bau 27, Raum 101 
Universitaet des Saarlandes    
Im Stadtwald             X400: fs-info@sbsvax.informatik.uni-saarland.dbp.de
D-6600 Saarbruecken 11         (preferred)
GERMANY (WEST)