Path: utzoo!utgpu!watmath!orchid!rbharding
From: rbharding@orchid.waterloo.edu (Ron Harding)
Newsgroups: comp.sys.atari.8bit
Subject: Re: Atari 800XL Parallel Bus Documentation
Summary: _Mapping the Atari_ has some goodies on it.
Keywords: 800XL PARALLEL BUS PORT
Message-ID: <327@orchid.waterloo.edu>
Date: 31 Jan 89 16:12:53 GMT
References: <307@ultb.UUCP>
Reply-To: rbharding@orchid.waterloo.edu (Ron Harding)
Organization: U. of Waterloo, Ontario
Lines: 27

In article <307@ultb.UUCP> ajy2208@ultb.UUCP (A.J. Yarusso (713ICS)) writes:
>The following is a message from Dennis Beach at Purdue..  He does not have
>authorization to post to the net, so I am relaying this for him:
>-------------------------------------------------------------------------------
>
>    For a long time I have been wanting to experiment with the parallel port
>in the back of my 800XL.  However, I can't find any info whatsoever about
>it. . . I would be greatly appreciative if anyone could give my this 
>information or tell me where I could find it.
>
>                        - Dennis Beach
>                            fwj@mentor.cc.purdue.edu
>                              Atari hardware hacker


    I've seen a fair bit of stuph about it scatterred around in _Mapping the
Atari_ from Compute! Books (The older editions have nothing on it).  I only
have an old-style 800 (considerably modified), so I haven't been able to
verify any of it.
    It think the XL ROM's are supposed to look at the port for some ROM, and,
if it is there, it is banked switched onto the place where the floating-
point library usually is, and executed.  You can make it install a new device
driver that way.  Very convenient (compared to AUTORUN.SYS files).
    I don't remember any of its other capabilities.  This is all from memory,
so don't quote me on it.

                                 Ron Harding.