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From: c60a-2ae@web4e.berkeley.edu.UUCP
Newsgroups: comp.sys.atari.8bit
Subject: Re: I/O Port expandtion  module
Message-ID: <6004@jade.BERKELEY.EDU>
Date: Fri, 20-Nov-87 16:58:55 EST
Article-I.D.: jade.6004
Posted: Fri Nov 20 16:58:55 1987
Date-Received: Sun, 22-Nov-87 13:30:59 EST
References: <871120-071531-1382@Xerox>
Sender: usenet@jade.BERKELEY.EDU
Reply-To: c60a-2ae@web4e.berkeley.edu.BERKELEY.EDU (John Kawakami -O^O-)
Organization: University of California, Berkeley
Lines: 28
Keywords: I/O, game ports
Summary: some references

The easiest way to interface some I/O device to an 800XL is through
the joystick ports.  Together they provide 8-bits parallel input/output
through the PIA chip in the computer.  The PIA has 16 bits of I/O but
the second 8 are used to bank switch memory.

There are also four pot inputs.
BTW the ports can be configured for x bits input and y bits out.

References:

Mapping the ATARI, Ian Chadwick, compute books
  Every ATARI owner MUST get this book, it's the best memory map around.

Bits & Pieces, a column in Analog computing.  Get the back issues first,
  they have clear data on setting up the ports.

An 8-bit parallel interface for the 800xl, Analog computing.  I forget which
  issue, but I can find it (probably was from 1985).  I believe this was an
  interface that provided handshaking and parity checking.  Hardware and 
  software.

Sams Computerfacts,  of course.
  I have neither their repair manuals or their programming manual, but
  people keep referring me to these.  Check electronics stores for these
  (not radio shaft).
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| JoHn KaWaKaMi alias spectacle -O^O- alias c60a-2ae@widow.berkley.edu      |
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