Swallow Amusement Machines

Connect an arcade joysick to your PC.

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This file was written by Greg Bendokus and is provided here for your information. We can accept no liability for damage caused to your PC from errors or omissions. If you find any errors, please let us know. It was written by an American so references of Radio shack and 120V can be substituted for Maplin and 240V.


This  project  will  allow  you to connect  an arcade-style
switch joystick to your PC's gameport through the use of the guts
from  a  PC  gamepad.    Yes, you read  correctly.  To be able to
complete this project, you must be in possession of the following:
1.  An arcade joystick, preferably the whole console  with sticks
and  buttons,  right  from  an arcade machine.  I used one from a
Double Dribble machine because  it has 2 nice sticks, each with 4
fire     buttons.  (I haven't  tried an  arcade  stick  that uses
microswitches - if you do, let me know how you make out.)  
2.  Some basic  knowledge of  electronics, i.e.   how  to  follow
circuit board traces and  the  difference  between hot and ground.
3.  One (or 2) PC gamepads.  What  kind to use it up to you - the
$5 ones from Babbage's work as  well as  a Gravis.  Don't get too
fancy because you're going to  junk everything except the circuit
board inside (hereafter referred to as the circuit card).
4.  A spool of wire,  available  from  Radio Shack, which will be
used to  connect  the  leaf  switches to the gamepad circuit card. 
Don't use anything too thick, or you will have problems with your
wire overlapping traces on the circuit card, causing all kinds of
headaches.  You will also need a  short  piece  of this wire with
both ends stripped, to use as a test lead.
5.  A soldering iron.  A good pencil iron from the Shack  will do,
just  don't  use  one  of those industrial 600 watt guns  and you
should be fine.  Since we'll be soldering directly to the circuit
card, don't use solder with a lot of rosin in it.
STEP 1 - Getting Ready
Take  your gamepad, remove all the screws, and open it up.  Throw
away  everything except the small circuit card, attached to which
is the cable that plugs into your PC.
If you have a common gamepad, you should see 2  groups of 4 round
traces on the circuit card.  4 of  these are for the fire buttons,
the other 4 are for the compass directions.  Determine which ones
are which.
Plug this shell of a gamepad into your PC and turn it on.
What you need to do now is to fire up any game program on your PC
that has a  joystick  calibration  function in it.  The choice is
yours, but make sure the program shows you the actual position of
the  joystick  on the screen.  MsPacPC is a good example.  If you
have Windows 95,  you  can  use  the joystick setup applet in the
control panel,  which is  my preferred  method.  Be sure you have
the joystick type set to "4 button gamepad" if you do this.  
NOTE:  I've done all of my wiring and soldering with  the gamepad
plugged in my  PC while it was turned on.  I can't be responsible
for any damage caused if  YOU  do  this, but unless you wire up a
120V AC line to the gamepad, I can't  imagine that anything could
get  fried.  Doing  it this way also  immediately allows to check
your work. Not recommend
STEP 2 - Finding the correct traces.
Each round trace on the gamepad card has 2 circuit traces leading
to it, usually one on each side.  By connecting a single piece of
wire  across  both  of these  traces, you "close the circuit" for
that switch and the gamepad  circuitry thinks you've just pressed
a direction (or a fire button).  What you want to do is take your
test  wire  and  manually  close  these  switches  and  see  what
direction is registered in your calibration program. The switches
on PC gamepads are usually arranged this way:
		   ||
     --------------||---------------
     |                             |
     |    U                   2    |
     |                   1         |
     | L     R                     |
     |                        4    |
     |    D              3         |
     |                             |
     -------------------------------
Take a piece of paper and jot down your findings.
Of  course,  if your  arcade  joystick setup is using only 2 fire 
buttons, you don't need to worry about buttons 3 and 4.  If   you 
are  using  2  joysticks  (you  will  need  a  joystick "Y" cable,
available at  the Shack), be  aware that  your PC is limited to 2
fire buttons each when using 2 sticks.
STEP 3 - Time to do some soldering.
Well, we're ready to solder.  Look at one of the leaf switches on
your arcade stick.  Each  one should  have 2  solder blades on it,
even though some have 3, like Wizard of Wor sticks.
All you do now  is simply solder each  blade to opposite  ends of
the traces for  that direction on  the game  card.   Let's do the
left direction first.  Move your joystick left and note what leaf
switches  close; it  won't always  be the  ones you  would think!
Now, solder a wire, about 6 inches long, to one of the  blades on
the back of the leaf switch.  Repeat  for the  other  blade.  Now
take these 2 wires  and  solder  them, one  to each side,  to the
left  gamepad  direction  trace  on  the  gamepad,  which  you've
determined earlier with your test lead.
Move  the joystick  left, and  with any  kind of luck, the screen
should say that you're moving the  joystick to the left.  If this
works,   congratulate  yourself  and  wire  up the  rest  of  the
directions  and any  fire buttons you're using.  Repeat the whole
process with another gamepad card if you have second joystick.
Some of you may note that I didn't mention you  could tie all the
grounds  together  on the  leaf switches and just run one wire to
the  low  side  of all  the  gamepad's  switches.   I seem to get
better  results  when I DON'T do this,  i.e. the stick calibrates
easier with my software.  It is also  a pain in the ass to find a
common  ground  on  a  gamepad - it's  just  easier  to make each
connection a separate one.  Feel free to experiment, though...
STEP 4 - Finishing up.
That wasn't so bad, huh?  Hopefully, when  you got  your joystick,
you  also got  the  wooden enclosure it came in.  If you did, you
can  use  a screw  and  attach the circuit card right to the wood
next  to the  joystick assembly.  Most gamepad circuit cards have
holes in them which make this easy to do.  Just make sure none of
your wires  interfere with the leaf switch blades.  You  can then
take a  piece  of  plywood, cut  it to fit the back of the wooden
console, and  nail  it  on,  making  a box.  Use  a staple gun to
fasten  the PC cord(s) to the wood so your handiwork isn't ripped
to  shreds  if  the  cord is   yanked.  You  should  now  have  a
completed  box with  one (or  two) cords  coming  out of the back,
ready to plug into your PC.
(If you didn't get the enclosure, well, build  something  to hold
the stick.  You're on your own for the fire buttons...)
Now,  plug the  thing into  your PC  and fire it up!  I recommend
trying Starforce to  really give the thing  a  good  work-out. If
you've  wired  up 2 sticks, the logical choice to try first would
be Robotron  (worth  building for  this  game alone).  Be sure to
calibrate the program(s) for your new stick(s) first! If all goes
well, you should be  quite  impressed with your work.  It  should
also become quite a apparent what youve been missing by trying to
play these emulators with a gamepad. :-)
POSSIBLE PROBLEMS:
1.  You may need to adjust the  gaps of  your leaf  switches.  If
you find  it  hard  to  move  diagonally,  check each  individual
direction  and adjust the switches for the best feel.  There is a
very fine  line  when  setting  leaf switches - either they don't
touch at all or they are  too  sensitive.  If  you  have  a  leaf
switch blade adjustment tool (looks like a knitting needle with a
gap on the end), this will be a much  easier  process.  I have no
idea where to get  one of  these tools - arcade machine repairmen
usually have them.  
2.  It may be hard to accurately calibrate the joystick  in  some
programs.  The only real problem I've had  is with  Mike  Cuddy's
Gyruss and Time Pilot emulators.  The  on-screen  joystick cursor
just goes nuts when I try to calibrate the stick.  I  resorted to
plugging in a normal gamepad, calibrating  the program with  that,
and then plugging the arcade stick back in.   No   problem.  Most
other programs, like Sparcade and  even  Doom(!), calibrate quite
easily and work like a champ.  MAME even calibrates automatically,
which is really nice. 
							   
3.  You may be tempted to try to use an Atari joystick instead of
an arcade stick.  Don't bother.  The 'bubble'  switches on  these
joystick's circuit cards have such a weak  electrical  connection
that the end result  will  always seem  to be  erratic,  with one
direction usually refusing to  work at  all.  Experimenting  with
this is where the whole project started, however.               
4.  I've tried my setup on several Soundblaster cards,  including
one of those $30 clone cards, with  no  problems at all.  I  have
NOT tried it  with  a GUS,  or  anything else for that matter.  I
can't  imagine  why  one  sound  card's  gameport  would   behave
differently  than any other, but in world  of  computer  hardware,
anything's possible.
-----------------------------------------------------------------
Well, there you have it.  If you  run into any  problems or  just
want to tell me how you like your new controller, please Email me
at:
bendokus@postoffice.ptd.net
Also, be aware  that  this  is  a  very  early  version  of  this
document,  the  bulk of  which  being   written at 2 AM.  If  you
feel  something  could  be  explained  better  or  come  up  with
an  easier  way  to do  something  you've  read  here, please let
me know.  I am looking for ANY  suggestions that  would   improve
this document, so please Email me at the above address.
You are free to upload this document to  whoever or  wherever you
like,  provided you do not modify it in any way.
I  will  not be  held  liable  for  any misuse of the information
contained  herein.   What  this  basically  means  is that  I  am
absolved of all blame if you blow up your PC.
-----------------------------------------------------------------
I'd like to thank all of the arcade  emulator  authors for  their
hard  work, allowing me to re-live a prized part of my  childhood.
Thanks also to Phil for reading my first  draft  of this document.
Your web page will definitely be missed!
Finally, special thanks must  go to my good friend Scott Stilphen,
arcade machine guru that he is, who  patiently endured  my temper
tantrums when we first  tried to wire up Atari sticks to a Gravis
pad.  Without him, this project would have never happened.
-----------------------------------------------------------------
Greg Bendokus
19th March. 1997
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