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Atari to Coco/Apple Joy Adapter [message #40298] Sat, 02 March 2013 22:09
knudsen is currently offline  knudsen
Messages: 173
Registered: February 2013
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Senior Member
Message-ID: <1575@ihnss.UUCP>
Date: Tue, 28-Jun-83 20:17:20 EDT
Article-I.D.: ihnss.1575
Posted: Tue Jun 28 20:17:20 1983
Date-Received: Wed, 29-Jun-83 10:18:12 EDT
Lines: 45

Due to popular demand (dozen requests!), here is the El Cheapo
adapter to feed Atari-type sticks into an analog X-Y type computer.
I assume your machine, like the TRS Coco, supplies +5 volts and
ground, and takes in two voltages from your existing analog
joystick pots, these voltages varying between GND and +5.
Also that your fire/jump button shorts its lead to GND.
And that your Y axis is positive downward (more volts=>down);
if not, reverse the UP & DOWN Atari connections.

Atari-type sticks indicate directions by grounding one or more
of four leads.  Two of these can just short your analog inputs to GND.
The other two each turn on a PNP transistor hanging from the +5 line,
whose collector pulls up the analog input.

You'll need a male DB-09 connector, two PNP transistors Q1 and Q2
(any kind will do, but not NPN!),
and two resistors around 3K ohms (lotsa leeway) R1 & R2.
If possible, mount the connector on an out-of-way side of existing
analog stick box and build circuit inside it.  This circuit likes
having your existing analog stick pots in parallel with it
(see below), otherwise you must add 4 more resistors.

WIRING LIST: Pin numbers refer to the 9-pin connector;
X, Y, FIRE, GND, and +5 to your existing computer (inside stick box).

1) +5 to Q1 emitter and Q2 emitter, and optionally to pin 7.
2) X to pin 3 and Q1 collector; optionally add pin 5.
3) Y to pin 1 and Q2 collector; optionally add pin 9.
4) Q1 emitter to R1.
5) Other end of R1 to pin 4.
6) Q2 emitter to R2.
7) Other end R2 to pin 2.
8) FIRE to pin 6.
9) GND to pin 8.

That's it!  To use, plug Atari (WICO, etc) stick into your modified
analog stick and CENTER it.  Then don't touch it, play with the
Atari stick.
Of course this scheme won't work for games using the full analog
potential of your existing stick (Polaris, etc), but is preferred
for Donkey Kong, Mega-Bug, and all those other ones where your
analog stick keeps making up dumb moves for you.
(What you really need is a self-centering analog stick, but
those are $55 and up...)
	En-joy,	mike k
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