Path: utzoo!utgpu!water!watmath!clyde!att!ncsc1!tsp
From: tsp@ncsc1.AT&T.NCSC (Tom Poindexter x8862)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Parallel Printer Port
Summary: Parallel port used bi-directionally
Keywords: Input
Message-ID: <59@ncsc1.AT&T.NCSC>
Date: 22 Sep 88 14:27:42 GMT
References: <8579@watdragon.waterloo.edu>
Distribution: na
Organization: AT&T NCSC, Englewood,CO
Lines: 23


I have seen advertised a software-based network package that runs through
parallel ports.  It's LanLink 5X from The Software Link; I think they use
some sort of special cable to get the proper signal lines routed.  This
would certainly imply both input & ouput through the port.

Also, check out the last few Byte issues; Steve Ciracia articles on 8051
development make use of an PC's parallel port as I/O to the controller.  He
shows a few hardware modifications (trace cuts, et.al.) that are needed
to make an IBM parallel port work, and mentions that many clone parallel
port boards should work bi-directionally as is.

If you are really just interested in seeing what is sent to a printer over a
network, I think you could just use any of the public domain printer
spoolers that use a disk file; spool to disk, then hex dump the file.  
With a little more work, just trap INT 17H (I think) on the PC that has 
the printer attached.  That's the standard BIOS interrupt to the printer
driver.  Any spooler or network redirector takes over this interrupt to
provide its' own services.

-tp
-- 
Tom Poindexter    {where ever}!att!ncsc5!tsp