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Article #41 (75 is last):
From: knudson@cs.UND.NoDak.Edu (Chad N.R. Knudson)
Newsgroups: freenet.sci.comp.atari.prog.8bit.resource
Subject: Dummy Cartridge for Atari 800
Posted-By: xx004 (aa853 - Craig Lisowski)
Edited-By: xx004 (aa853 - Craig Lisowski)
Date: Sun Sep 18 03:15:15 1994


Schematic for Dummy Cartridge

This modification tricks the computer into thinking a cartridge is
installed.  This is a terribly crude attempt at a schematic for it,
since the original notes I had are quite old, and were just a few
scribbles.  I'm sorry that I don't have better references to the
pins of the Atari board for the cartridge port, but I'm sure you
can figure them out.

Parenthesis in the diagram indicate that the two lines are not
connected.

                                                   Switch

                                                   +--/ -+
                                                   |     |
                 +---------------------------------+     +----+
                 |                                            |
                 |  |  |  |  |  |  |                          |
              +----------------------+                        |
              + 14 13 12 11 10  9  8 +                        |
              +                      +                        |
              +> 7404 Hex Inverter   +                        |
              +                      +                        |
              +  1  2  3  4  5  6  7 +                        |
              +----------------------+                        |
                 |  |  |  |  |  |  |                          |
            +----+  |              |                          |
            | +-----+              +-----------------------+  |
            | |                                            |  |
            | |  Pins on bottom of circuit board for the   |  |
            | |  LEFT cartridge                            |  |
            | |                                   +--------)--+
            | +-----------------------------------(--+     |
            | |                                   |  |     |
            | |  O  O  O  O  O  O  O  O  O  O  O  O  O  O  |
            | |                                            |
            | |  O  O  O  O  O  O  O  O  O  O  O  O  O  O  |
            | |  |  |                                |     |
            | +--+  +--------------------------------)-----+
            +----------------------------------------+

Pin 14 of the 7404 connects to one side of the switch
Pin 2  of the 7404 connects to two of the cartdige port pins, all
       other pins of the 7404 connect to only one.

Atari 800 Computer upside down, keyboard toward you


-- 
Chad Knudson    knudson@cs.und.nodak.edu        Center for Aerospace Sciences
                +1 701 777 4571                   University of North Dakota
-- 
Michael Current, Keeper of the 8-Bit Atari FAQ & Vendor/Developer Lists,
 Cleveland Free-Net Atari SIGOp: aa700, 


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