Path: utzoo!mnetor!uunet!unisoft!gethen!farren
From: farren@gethen.UUCP (Michael J. Farren)
Newsgroups: comp.sys.ibm.pc
Subject: Re: hooking PC's together
Message-ID: <730@gethen.UUCP>
Date: 5 Mar 88 15:24:14 GMT
References: <673@pasteur.Berkeley.Edu> <63200030@convexe> <1305@qetzal.UUCP> <3438@cup.portal.com> <1894@uwspan.UUCP>
Reply-To: farren@gethen.UUCP (Michael J. Farren)
Organization: There's Unix there in Oakland
Lines: 23

In article <1894@uwspan.UUCP> root@uwspan.UUCP (John Plocher) writes:
>+---- Isaac_K_Rabinovitch@cup.portal.com writes in <3438@cup.portal.com> ----
>| ->+Is there a way to hook to PCs together via the parallel ports?
>| 
>| As I said before, I'm puzzled that the parallel approach isn't more
>| popular.  Perhaps it's harder to implement.
>+----
>
>Because the parallel adapter in the PC and AT is UNI-Directional - it can
>send but it can not receive data.

I was originally going to respond to this in exactly the same way, until
I took the time to break out the schematics for the IBM parallel interface
and look for myself.  Sorry, John, but it IS bidirectional - there is
an input data buffer on those data lines as well as an output buffer.
You have to switch a bit or two on one of the 8255's to get data in,
but it would seem that's all there is to it.

-- 
Michael J. Farren             | "INVESTIGATE your point of view, don't just 
{ucbvax, uunet, hoptoad}!     | dogmatize it!  Reflect on it and re-evaluate
        unisoft!gethen!farren | it.  You may want to change your mind someday."
gethen!farren@lll-winken.llnl.gov ----- Tom Reingold, from alt.flame