Checksum: 44508
Path: utzoo!utgpu!tj
From: tj@gpu.utcs.toronto.edu (Terry Jones)
Date: Fri, 11-Mar-88 11:54:57 EST
Message-ID: <1988Mar11.115457.17080@gpu.utcs.toronto.edu>
Organization: University of Toronto Computing Services
Newsgroups: comp.sys.ibm.pc
Subject: Re: hooking PC's together
Summary: Bi Directional Parallel
References: <673@pasteur.Berkeley.Edu> <63200030@convexe> <1305@qetzal.UUCP> <3438@cup.portal.com> <1894@uwspan.UUCP> <730@gethen.UUCP> <4368@june.cs.washington.edu>
Reply-To: tj@gpu.utcs.UUCP (Terry Jones)
Distribution: na

If you look in the tech ref you get the distinct impression that it is 
unidirectional. But if you read carefully they indicate that the data presented
as input to the parallel port is OR'ed with the data currently output
to the port. So if you write zeroes then read you can do it. Also there are 
interrupts. 

By the way, I just tried a product called Lap-Link for use with laptops
when you want to transfer files to and from your "base" pc...
It goes like stink across the serial port, the screen is split
in half and on half is the directory of the PC you are on and the other
half is the remote pc. Lets you do copies, group copies, renames, wildcard
copies, change drives and directories etc, ON EITHER MACHINE!!!
Their plus version would allow one computer to use the other
computer hard disk AND PRINTER as if they were in the computer!!!
I transfered a 980K TIFF scanner image here in 4 minutes between 2 XT's.
(206) 483-8088 for info... (I have no connection AT all with this company,
in fact, I have only seen the product, I phoned them for info today.)
tj

BTW, Lap Link uses the serial ports at speeds ranging from a paltry
9600 baud to 115K baud... Thats right, 9600 is the slowest and 
apparently only needed for some strange hardware!!!