How To Convert a Sega Genesis Controller to Atari Standard Pinout

From: Michael Current (aa700@cleveland.Freenet.Edu)
Date: 03/07/98-05:51:12 PM Z

From: aa700@cleveland.Freenet.Edu (Michael Current)
Subject: How To Convert a Sega Genesis Controller to Atari Standard Pinout
Date: Sat Mar  7 17:51:12 1998

Date: 2 Mar 1998 20:07:39 GMT

I did this up before I read a message here that seems to indicate that
unmodified Sega controllers will work on an Atari 8-bit.  If so, I
would like to hear about it!

For other machines (like my TI-99/4A primary rig), an almost-compat
like the Sega controller will not work, so the following mod is


How To Convert a Sega Genesis Controller to Atari Standard Pinout

The Sega controller almost has the same pinout as an Atari Standard
joystick (wonder why!).  The lowest-cost model (no-frills, three
fire buttons, ~ $10 at Toys R Us) can easily be modified for use with
Atari STs, Atari 8-bitters, TI-99/4As (mod tested on these) and probably
all other home computers from the 70's and 80's.  With this mod, the
movement pad will work like a regular joystick, and the middle fire
button ("B") will work as a joystick fire button.

1. Unscrew the 6 screws and lift off the back.  Remove the cable/board

2. Disable the single logic device (74HC157) by:
   a. Cutting pins 4, 7, and 9, or
   b. Cutting the entire chip clean off!

   Note that, holding the board so the "notch" at the end of the
chip is "up", pin 1 is at the upper left corner.  Pins number down the
side and up on the other side, with pin 16 opposite pin 1.  Remember
that when looking at the reverse (circuit) side, the image is flipped!

3. Make a solder bridge between pins 3 and 4, 6 and 7, and 9 and 10.  If
globbing on enough solder to make the bridge doesn't appeal to you, use
a bit of wire, like a bit of resistor lead from your junkbox.

1. The one-side circuit board is pretty easy to trace out.  You could
easily jump the other fire buttons to "B" so they all work.

2. Supposedly, with a bit of ingenuity, you could put a very small
three-pole, double-throw switch somewheres on the controller, NOT
cut the chip off the board (but merely clip pins 4, 7, and 9), and
wire the switch in such that

   pin 3/6/10 ------o\
                      \o------  where pin 4/7/9 used to connect
                                on the circuit board
   pin 4/7/9  ------o
   (stubs on the chip)

And you can switch the controller between Sega and Atari modes!
(This has not been tried, it just stands to reason!)
* David Ormand           *** Southwest 99ers *
* *** Tucson, Arizona *
**************************** TMS9900 Lives!  *
Michael Current,
8-bit Atari FAQ and Vendor Lists,
Cleveland Free-Net Atari SIG, telnet:// (go atari)
St. Paul Atari Computer Enthusiasts,

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