blgardne@esunix.UUCP (Blaine Gardner) (02/18/88)
A one line mention of my trackball hack has stirred some interest again,
and since it's been more than a year since I posted it, I'm reposting my
trackball-to-Amiga-mouse hack. I'm also including the other two
trackball hacks that have appeared on the net. Choose the one you like
best, and kiss your warranty goodbye!
========================================================================
Notes from George Robbins on my original posting:
========================================================================
Per request, I am reposting the original article on converting WICO and
perhaps Atari 2600 trackballs to mouse-compatible devices. While I have
not tried the conversion, what the original author describes seems to
be quite reasonable.
One other approach that might be easier would be to obtain a spare mouse,
extract the little logic board and attach it to the various LEDs, photo-
sensors and switches...
The original article in comp.sys.amiga describes how to convert WICO
and Atari 2600 track balls to work with the Amiga. Converting for the
Atari ST is essentially the same, except for some disagreement between
Atari and CBM on which quadrature signals go to which "joystick" lines.
Pin Amiga Atari
=== ===== =====
1 Vertical X-B
2 Horizontal X-A
3 Vertical-Quatrature Y-A
4 Horizontal-Quadrature Y-B
5 Pot X N.C.
6 Left Button Left Button
7 +5V +5V
8 Ground Ground
9 Pot Y-Right Button Right Button
As you can see, the pin-outs are compatible enough that no harm will result
if the two are interchanged, however since the quadrature outputs don't
match up you will get pointless twitching instead of useful motion. Simply
switch the wires going to pins 1 thru 4 until you get it right.
A minor problem is that the WICO trackballs are discontinued, so unless you
already know where to find one, you may have problems.
===========================================================================
My original posting:
===========================================================================
Original (corrected) article from blgardne@esunix.UUCP (Blaine Gardner):
Title: Wico trackball mouse VERSION 2.0 (BUG FIX & ATARI NOTE)
Ok, here it is, sorry I took so long to post it. I have tried to make this
understandable, if you don't know what an LM 339 or a DB9 is, maybe you
shouldn't try this.
---------------------------------------------------------------------------
Wico track ball modification.
Converting the Wico track ball into an Amiga mouse compatible track ball
is a fairly simple procedure. But if you are uncomfortable with a soldering
iron, get some competent help.
You could damage your Amiga if you make a mistake when
assembling this project! You could also void your Amiga
warranty! You will definitly void your trackball warranty!
YOU HAVE BEEN WARNED!!!
Ok, now that that's out of the way here are the gory details.
The stock trackball contains a small pc board, this will be removed and
replaced with one containing an LM 339 quad comparator.
The comparator simply converts the output of the opto-coupler to a TTL
level pulse. Both the X and Y axis use two emitter-detector pairs. The
output of each of these detectors is fed through one of the comparators.
The output of the comparator is then fed to the Amiga's mouse port. Since
the output of the trackball will be identical to the mouse's output, the
modified trackball will work with ALL software that uses the mouse.
Here we go!
Remove the 6 (six) screws from the bottom of the trackball case and
open it (right-side-up please). In the lower-right corner there is a small
pc board with two connectors. Remove the board & connectors. You can toss
the board, and the cable that has the joystick connector. (The cable only
has 7 wires and we need 8. You can scrounge the 11 pin male header off of
the board.)
Cut a piece of perf board the same size as the original board. Just
make sure it fits in the same place as the original. The plastic grooves
will hold it perfectly.
Two cautions here: make sure the top can be screwed down without hanging
up on the new board, and make sure all your components will clear the
standoff near the board!
Using the (crude) schematics below, wire up the circuit. You will need to
drill a hole in the case to mount a second switch (for the right button).
Make sure the second switch will clear all existing hardware! Wire the second
switch between ground and pin 9 on the DB 9 connector.
It is a good idea to place a medium sized capacitor (10-20 uf) across +5 and
ground where power enters the perf board.
Parts List:
Wico Trackball #72-4545
Wico Corporation
Consumer Division
6400 W. Gross Point Road
Niles, Illinois 60648
800-323-4014
Joystick Extension Cord Radio Shack #276-1978
LM 339 Quad Comparator Radio Shack #276-1712
14 pin DIP Socket Radio Shack #276-1999
Soft-Touch Switch Radio Shack #275-1566
Perf Board
11 pin Male Header (can be removed from Wico)
10 - 20 microfarad capacitor (12V or higher)
Resistors (1/4 or 1/8 Watt, 5% tolerance)
280 Ohm (4 each)
3.3K Ohm (4 each)
6.8K Ohm (4 each)
100K Ohm (4 each)
---------------------------------------
Wico TrackBall Internal Connector
(Color code assumes Wico is consistent in their wiring.)
1 Pushbutton White
2 +5 (Y-axis) Red
3 +5 (X-axis) Red
4 Ground (Pushbutton) White
5 Ground (X-axis) Black
6 Ground (Y-axis) Black
7 N/C ---
8 Y-axis output Violet
9 Y-axis output Blue
10 X-axis output Green
11 X-axis output Yellow
---------------------------------------
Pinouts for LM 339
------------------------
| 14 13 12 11 10 9 8 |
) |
|. 1 2 3 4 5 6 7 |
------------------------
1 Output 2
2 Output 1
3 +5 Volts
4 Input 1-
5 Input 1+
6 Input 2-
7 Input 2+
8 Input 3-
9 Input 3+
10 Input 4-
11 Input 4+
12 Ground
13 Output 4
14 Output 3
---------------------------------------
Amiga Mouse Connector (DB 9 Female)
-------------
\ 5 4 3 2 1 /
\ 9 8 7 6 /
---------
1 V pulse
2 H pulse
3 VQ pulse
4 HQ pulse
5 N/C
6 Button 1 (Left)
7 + 5 Volts
8 Ground
9 Button 2 (Right)
----------------------------------------------
Connections from Wico | Connections from LM 339
11 pin socket to LM 339 | to DB9 (Mouse port connector)
|
Wico -> LM 339 | LM 339 --> DB9
---- ------ | ------ ---
1 (to pin 6 on DB9) | 2 1
2 3 \__+5 Volts | 13 2
3 3 / | 1 3
4 12 \ | 14 4
5 12 >--Ground | N/C 5
6 12 / | (pin 1 on Wico) 6
7 N/C | +5 Volts 7
8 4 | Ground 8
9 6 | 9
10 10 |
11 8 |
---------------------------------------
O +5 Volts O +5 Volts
| |
\ \
3.3K Ohm / / 6.8 K Ohm
\ 100K Ohm \
| |
+-----/\/\/\/-------+ |
| /| | |
| / +|---+------+ (Pins 5,7,9,11)
| /1/4 | |
Output to /__|________/ LM | |
Amiga \ \ 339 | \
(Pins 1,2,13,14) \ | / 280 Ohm
\ -|--+ \
\| | |
| |
| |
Input from ball >-------+ -----
(Pins 4,6,8,10) | ---
| -
\
3.3K Ohm /
\
|
|
|
-----
---
-
-------------------------------------------------------
There it is! The above information was obtained from the Amiga Hardware
Reference Manual, and from tearing apart my mouse & trackball and trace-
ing out the schematics myself. (Mostly from tearing my hardware apart!)
Any errors in the above information are mine (but for a few hours work
they can be yours too! |^) ), not Evans & Sutherland's. They are kind
enough to pay me to play with their computers, they have no control over
my ramblings here on usenet.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
The above infomation is the correct version. In my first posting + 5 volts
and button 2 were switched on the DB9 pinouts.
There have been a lot of inquiries about doing the same modification on
the Atari 2600 trackball. I hadn't seen the Atari untill two days ago, but
I can now tell you that the same procedure will work for it. In fact it is
a little easier on the Atari trackball because the LM339 is already present.
Just remove all the components from the board except the 339, the supply
voltage filter (inductor + electrolytic cap near the 6 pin header), and
resistors R9 - R18. Actually you'll have to remove those too because they
are the wrong values, and the 339 socket blocks several traces that need
to be cut. (As I remember 430K and 10K should be swapped for 100K and 3.3K
respectively.)
The biggest problem is that Atari wired the 339 as a non-inverting
comparator, and Amiga uses an inverting comparator. So you'll have to CUT
AND JUMPER (those that flinched may leave the room) to get the inverted
configuration (see above data for the correct circuit).
I don't plan to do a detailed plan for the Atari trackball, if the above
information doesn't mean much, don't try it yourself.
This general plan should work for all trackballs that use a pair of opto-
couplers on each axis. The old TG trackball for the Apple II (and probably
other computers) will NOT work since it uses a pair of pots.
I hope this helps all you hardware hackers that can't live without a real
trackball. Have fun, and don't blow up your Amiga!
===========================================================================
Here is the second trackball hack that showed up on the net. This is the
easiest one for the Atari 2600 trackball.
===========================================================================
From msl5864@ritcv.UUCP Wed Dec 31 17:00:00 1969
Relay-Version: version B 2.10.1 6/24/83; site esunix.UUCP
Path: esunix!uplherc!utah-gr!utah-cs!ut-sally!husc6!seismo!rochester!ritcv!msl5864
From: msl5864@ritcv.UUCP
Newsgroups: comp.sys.amiga
Subject: Atari Trackball Conversion
Message-ID: <161@ritcv.UUCP>
Date: Fri, 13-Mar-87 00:19:16 MST
Article-I.D.: ritcv.161
Posted: Fri Mar 13 00:19:16 1987
Date-Received: Sun, 15-Mar-87 00:14:00 MST
Reply-To: msl5864@ritcv.UUCP (Michael S. Leibow)
Organization: Rochester Institute of Technology, Rochester, NY
Lines: 43
I just bought a couple of Atari brand trackballs at the local hobby store
for 14 bucks and decided to convert one of them to work like a mouse for
my Amiga. I followed the instructions that were given a while back for Atari
trackballs, and totally ruined the thing. After working on a second one, I
studied the circuits myself and have successfully made the modification.
The first part of the modification is quite easy and doesn't need any soldering.
THe second part will involve a minor amount of soldering and that is so that
the right switch can be disconnected from the left and work like the mouse.
Part I. Open the trackball by removing the screws and prying the two halves
apart. There will be a 6 pin connector at the end of the DB-9 cable. Scratch
away the foil paths on the circuit board that lead to pins 1 through 4 from
left to right. (Two of the foil paths are on one side of the circuit board
and the other two are on the other side). Connect the following pins
from the 6 pin connector to the pins of the LM339.
6 PIN CONNECTOR LM399
--------------- -----
1 -> 14
2 -> 2
3 -> 13
4 -> 1
I accomplished this by piggy backing a second socket on top of the LM339 and
just plugging wires from the connector to the socket. This should complete
part I. To test it out, plug it in to the Amiga and try to use it like a
mouse. Both buttons will work like the left button on the mouse.
Part II. In order to make the right button work like the right button on the
mouse you will have to buy another cable. In the trackball I bought, there was
no wire for pin nine of the DB-9 connector and that is where the right switch
goes. So, cut off the old cable and solder the remains of the old cable to the
new cable. Cut the red wire connecting the two switches so that the majority
of the length is attached to the right switch. COnnect the wire from the right
switch to pin nine of the cable. Now the trackball should work just like a
mouse. Be very careful that you don't connect the wrong wires from the DB-9
cable to the six pin connector and switches. On my first attempt I switched
pins 7 and 8 by accident and blew some of the chips on the circuit board.
I have already built this circuit and I don't believe there are any mistakes
in this posting. I am sorry in advance for any mistakes there might be. Also,
I have nothing to do with Commodore or Atari.
============================================================================
This is the third (and final?) trackball hack to appear. The advantage
of this one is it allows the Atari 2600 trackball to be switched between
joystick and Amiga mouse modes. When I built it, the mouse response was
pretty jumpy compared to the other two hacks. If you want a game
controller, use this hack. If you want a smooth mouse, use one of the
other two.
=============================================================================
Path: esunix!uplherc!utah-gr!utah-cs!ut-sally!husc6!mit-eddie!mit-amt!mit-caf!rajeev
From: rajeev@mit-caf.UUCP (Rajeev Jayavant)
Newsgroups: comp.sys.amiga
Subject: Atari Trackball Modification
Message-ID: <367@mit-caf.UUCP>
Date: 8 Jun 87 06:22:47 GMT
Reply-To: rajeev@mit-caf.UUCP (Rajeev Jayavant)
Distribution: na
Organization: Massachusets Institute of Technology
Lines: 159
For those of you who've been waiting for an inexpensive trackball,
here are the modifications for converting an Atari trackball (model
CX22) to emulate an Amiga mouse. This device is different from the
Wico trackball which has been previously mentioned on the newsgroup.
One nice feature of the Atari trackball is a joystick emulation mode
in which it can be used in place of a joystick. It can be plugged
directly into the Amiga and used in the joystick mode. Unfortunately
a few modifications are needed to use it in place of the mouse.
KayBee toy stores in the Boston area currently have these things on
sale for $9.99 so you should be able to have a fully functional
trackball for well under $20.
For those who grow squeamish at the sight of a dismantled trackball, it
is possible to build an adapter that can be plugged in between the
Amiga and the trackball. The only disadvantage of the adapter
apporach is that the second trackball button cannot be used as the
right mouse button. Please send me email if you would like
instructions for constructing the in-line adapter.
Disclaimer: While I beileve that the instructions provided here are
correct, I do not claim any responsibility for the results of your
actions. I seriously doubt you can injure your Amiga even if you make
a mistake in construction; I do not know if the same can be said for
the trackball.
Now for the moment you've all been waiting for. You will need a
74LS86, a 74LS157, and one Radio Shack joystick extention cord (or
equivalent 9 conductor cord with a female DB9 connector on the end).
Note: Radio Shack does not carry the IC's, but they should be commonly
available.
The cord is necessary because the trackball comes with a 7 conductor
cord, making it impossible to use both buttons separately.
Unfortunately all the Radio Shacks in my area are out of the extention
cord thus I had to reuse the cord that came with the trackball and do
not yet have a functioning right mouse button.
Open the trackball by removing the four screws on the bottom of the
case. Separate the two halves of the case by holding on to the bottom
half and pushing a screwdriver through one of the two holes near the
middle of the case (they look like they should have recessed screws in
them but there aren't any screws). Be careful when separating the two
halves otherwise the ball will land on your foot and roll across the
floor :-).
In the upper left corner there is a 6 pin connector to which the
incoming cable is attached. Remove the connector to expose the six
signal pins. I will refer to these as T1 thru T6 (from left to
right). The signals on the pins are:
Pin | Joystick Mode | Trackball Mode | Wire Color
----+---------------+--------------------+-----------
T1 | left | vertical direction | green
T2 | right | vertical pulse | violet
T3 | up | horizontal dir | white
T4 | down | horizontal pulse | blue
T5 | +5 V in | +5 V in | orange
T6 | ground | ground | black
----+---------------+--------------------+-----------
The horizontal and vertical pulses (T4 and T2) can be fed directly to
the Amiga (to the right pins of the game port, of course), but the
HQpulse and VQpulse required by the Amiga must be constructed from
the available signals. The HQpulse is simply the XNOR of the Hpulse
and the Horiz. direction. Similarly the VQpulse is the XNOR of the
Vpulse and Vert. direction. The two XNOR gates are implemented using a
74LS86 (quad XOR gate). The 74LS157 is a quad 2-to-1 multiplexer that
is used to preserve the joystick emulation mode.
CONSTRUCTION NOTES
------------------
There is plenty of room inside the trackball case, so you can choose
just about any construction method you desire. I chose to wire wrap
the circuit on a tiny piece of perfboard and mounted it in the right
side of the case. I attached the circuit to the trackball by wire
wrapping directly onto the posts exposed by removing the six-pin
connector. I soldered the incoming cable onto a DIP header (also from
Radio Shack) which is then plugged into a third socket on my little
circuit board. Being able to easily remove the cable is a big plus
since you can keep it out of your way 'til the very end.
The schematic below shows how to construct the little circuit board.
The pins on the gameport connector are referred to as P1 thru P9.
Connect the circuit board to the appropriate pins (T1-T6 and P1-P9).
The joystick/trackball switch is the little slide switch near the
lower left corner of the trackball (top view). You will need to
solder a little wire to the bottom-most of the three contacts on the
switch.
To get to the contacts on the bottom of the switch, you will need to
remove the PC board in the trackball. Lift out the "cue ball" and the
two rollers it is resting on. Then remove the two screws holding down
the PC board and lift it out. Reverse the process after you've
attached the wire to the switch contact with a dab of solder.
To wire the buttons, do the following:
1) Cut the red wire connecting the two switches together.
(also cut the red wire leading to the incoming cable).
2) Connect the black wire to ground (T6).
3) connect the red wire from the left button to P6.
4) connect the red wire from the right button to P9.
SCHEMATIC
---------
Joystick/Trackball Switch -----------+
(Bottom contact) |
T2-----------------------+-------+---|--------------+
T1---------------------+ | | | |
| | | | |
T3------+--------------|-|-----+ | +-|--------------|--------------P3= VQpulse
| | | | | | | |
T4----+-|--------------|-|-----|-|-|-|--------------|--------------P2= Hpulse
| | | | | | | | |
T5--+-|-|------------+-|-|-+---|-|-|-|------------+-|--------------P7= +5V
| | | | | | | | | | | | |
| | | +--------+ | | | | | | | | +--------+ | |
| | +-|1 7 14|-+ | | | | | | +-|1 7 16|-+ |
| +---|2 4 13|---+-|-|---|-|-|---|2 4 15|---|-+
| +-|3 L 12|-----+ | +-|-|-|---|3 L 14|---+ |
| +-|4 S 11|-+ | | | | +---|4 S 13|-+ |
+-----|5 8 10|-+ | | +-|-----|5 1 12|-|---|------------P4= HQpulse
+---|6 6 9|-------+ | +-----|6 5 11|-|---+
| +-|7 8|---------+ +---|7 7 10|-|---+
| | +--------+ | +-|8 9| | |
| | | | +--------+ | |
+-|--------------------------|-|------------+ |
| +-|----------------|-----------P1= Vpulse
T6=GND--+-------+--------------------+----------+-----+-----------P8= GND
| |
+-----------+ +------------+
|Left Button|----+ |Right Button|----------P9= button 2
+-----------+ | +------------+
+--------------------------------------P6= button 1
TROUBLESHOOTING
---------------
Reassemble the trackball after making all connections. Set the
joystick/trackball switch to "trackball" and try using the trackball
in place of the mouse. If all has gone well, your pointer should move
smoothly in response to the trackball movement.
If there is no movement or the movement is *very* jittery,
double-check your connections. It is very likely that something is
not connected or that two signals have been switched. It may help to
try out the joystick emulation mode if you think signals have been
crossed (it'll be easier to tell which signals have been crossed!).
Good Luck!
Rajeev
--
/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/
Rajeev Jayavant Quote: "Excuse me. I've lost my marbles." (P. Opus)
ARPA: rajeev@caf.mit.edu UUCP: ....!mit-eddie!caf!rajeev
===========================================================================
Ok, there you go, the collected wisdom of the ages on the subject of
hacking trackballs into Amiga mice. Since they are identical in function
to the standard mouse (once modified), they will work with 100% of
existing software. And Kay-Bee Toys still has a bunch of them for under
$10. Happy hardware hacking!
--
Blaine Gardner @ Evans & Sutherland 540 Arapeen Drive, SLC, Utah 84108
UUCP Addresses: {ihnp4,ucbvax,allegra,decvax}!decwrl!esunix!blgardne
ihnp4!utah-cs!esunix!blgardne usna!esunix!blgardne
"Nobody will ever need more than 64K." "Nobody needs multitasking on a PC."mark@speedy.cs.wisc.edu (Mark Spankus) (02/23/88)
Well after seeing the recent postings on trackball hacks, I had to put in
my 2 cents worth. I recently purchased an Atari 2600 trackball from the
local KayBee toy store for $9.00. After some initial probing and testing
I discovered that the outputs from the comparator were the same polarity
as my amiga mouse, so no additional inversions were necessary. (Hey did
you know that they work the same way even if the signals are inverted?)
Anyway some friends wanted to make their own Trak-mice so I wrote up my
experiences. It requires no additional ICs or circuit modifications, works
without problems and leaves the original cable intact in case you ever want
to play missile command on your 2600 again. :-)
Atari2600 Trackball Modifications
==================================
NOTE: These modification void your warranty! Don't attempt this if you're
afraid of soldering irons :-)
Unfortunately the cable supplied with the Atari trackball is missing the
wire which has the right mouse button signal. Therefore it is necessary to
either replace the existing cable with one that has the additional wires
or install a second one devoted to just the amiga. I chose the second
approach. Since I didn't want to hack up another joystick extension cord,
I mounted a female DB-9 on the right rear corner of the case, and can now
just plug the extension cord into the amiga & then into the trackball. This
also allows you to leave the original cable supplied with the trackball in
place so that you can use it for it's original purpose. I later removed it
to limit the amount of wire dangling about. Installing a DB-9 is the
SUGGESTED approach!
Alternately you could use all the existing parts and live without the
right mouse button. This will require you to cut several traces and give
up the original use of the trackball. (You will make it amiga-only)
In this case cut the traces on the top and bottom of the circuit board
leading to the colors white, blue, green, brown on the cable to circuit
board connector. Make the connection listed below but replace the
references to pins 1,2,3,4 with the positions of the colors white,blue,
green, brown on the circuit board connector. You won't need to get any
additional parts or make any additional modifications to the buttons,
but you won't have a right mouse button. :-(
-----------------------------------------------------
Parts List:
Joystick Extension Cord Radio Shack #270-1705 $4.99
Female DB-9 Connector Radio Shack #276-1538 $2.49
-----------------------------------------------------
First you will need to open the trackball. There are four screws in the
corners of the base. There are also two plastic posts which slide together
and are difficult to get apart. Remove the screws and slide a knife or
other flat object between the halves. Gently pry the lid off. The posts
are located in the middle of the trackball near the top and bottom. The
top will come completely off. Next take out the ball and the two metal
bars with the slotted wheels attached and set them aside.
If you choose to, mount a DB-9 connector in the right rear corner of the
trackball. This will allow you to keep the extension cord intact. If you
don't want to do this, you can cut off the male end of the extension cord
and drill a small hole in the back to let the cable pass through.
Now on to the wiring. There are several solder pads located on the top
of the circuit board in the lower left corner. They are labeled TP1 - TP6.
There is another one labeled TP13 to the right of TP6. There is also a
resistor labeled R17 (a 10k). You will need to make connections to most
of these points and to the top of R17 (away from the edge of the board).
Using a low wattage soldering iron, make the connections from the DB-9
to the points on the circuit board as listed below. Use any small
wire (wire wrap wire is fine, but a bit small). If you have decided to
directly connect the joystick cord, you will need to figure out the color/pin
arrangement to make the correct connections.
--------------------------------------
Amiga Mouse Connector (DB 9 Female)
-------------
\ 5 4 3 2 1 / Front
\ 9 8 7 6 / View
---------
1 V pulse ----------> TP3
2 H pulse ----------> TP2
3 VQ pulse ----------> TP4
4 HQ pulse ----------> TP1
5 N/C
6 Button 1 (Left)
7 + 5 Volts ----------> To top end of R17
8 Ground ----------> TP13
9 Button 2 (Right)
[Remember the pin numbers are switched left to right when viewing from the
rear of the connector!]
------------------------------------------------
The buttons as supplied are wired together. You will need to cut the red
wire on the right hand switch at a distance long enough to reach pin 9 on
the DB-9. The other end of the wire will be connected to pin 6. If you are
going to remove the original cable, you will also need to make an additional
ground connection from the black wire to pin 8 on the DB-9 or to TP13 which
ever is easier.
This concludes the wiring. Make sure all your connection are secure and
that there are no shorts. Also make sure that the wires will not interfere
with the movement of the ball or slotted disks.
Put the metal bars and ball back in the trackball. Power up your amiga and
plug the trak-mouse in. If anything strange happens, remove the cable
IMMEDIATELY and verify your wiring. The only really damaging mistake is to
make the wrong connections to either the +5 or ground. If everything is ok,
put the top on & screw it back together. Have fun with your new Trak-Mouse!
[It goes without saying that none of you would ever plug both cables into
two machines at once.... Right? You Betcha!]
Mark Spankus
University of Wisconsin - Madison
Computer Science Systems Lab
path: ...!{allegra,heurikon,ihnp4,seismo,ucbvax,uwm-evax}!uwvax!mark
arpa: mark@speedy.cs.wisc.edu
Mark Spankus
University of Wisconsin - Madison
Computer Science Systems Lab
path: ...!{allegra,heurikon,ihnp4,seismo,ucbvax,uwm-evax}!uwvax!mark
arpa: mark@speedy.cs.wisc.edumark@speedy.cs.wisc.edu (Mark Spankus) (02/23/88)
Well after seeing the recent postings on trackball hacks, I had to put in
my 2 cents worth. I recently purchased an Atari 2600 trackball from the
local KayBee toy store for $9.00. After some initial probing and testing
I discovered that the outputs from the comparator were the same polarity
as my amiga mouse, so no additional inversions were necessary. (Hey did
you know that they work the same way even if the signals are inverted?)
Anyway some friends wanted to make their own Trak-mice so I wrote up my
experiences. It requires no additional ICs or circuit modifications, works
without problems and leaves the original cable intact in case you ever want
to play missile command on your 2600 again. :-)
Atari2600 Trackball Modifications
==================================
NOTE: These modification void your warranty! Don't attempt this if you're
afraid of soldering irons :-)
Unfortunately the cable supplied with the Atari trackball is missing the
wire which has the right mouse button signal. Therefore it is necessary to
either replace the existing cable with one that has the additional wires
or install a second one devoted to just the amiga. I chose the second
approach. Since I didn't want to hack up another joystick extension cord,
I mounted a female DB-9 on the right rear corner of the case, and can now
just plug the extension cord into the amiga & then into the trackball. This
also allows you to leave the original cable supplied with the trackball in
place so that you can use it for it's original purpose. I later removed it
to limit the amount of wire dangling about. Installing a DB-9 is the
SUGGESTED approach!
Alternately you could use all the existing parts and live without the
right mouse button. This will require you to cut several traces and give
up the original use of the trackball. (You will make it amiga-only)
In this case cut the traces on the top and bottom of the circuit board
leading to the colors white, blue, green, brown on the cable to circuit
board connector. Make the connection listed below but replace the
references to pins 1,2,3,4 with the positions of the colors white,blue,
green, brown on the circuit board connector. You won't need to get any
additional parts or make any additional modifications to the buttons,
but you won't have a right mouse button. :-(
-----------------------------------------------------
Parts List:
Joystick Extension Cord Radio Shack #270-1705 $4.99
Female DB-9 Connector Radio Shack #276-1538 $2.49
-----------------------------------------------------
First you will need to open the trackball. There are four screws in the
corners of the base. There are also two plastic posts which slide together
and are difficult to get apart. Remove the screws and slide a knife or
other flat object between the halves. Gently pry the lid off. The posts
are located in the middle of the trackball near the top and bottom. The
top will come completely off. Next take out the ball and the two metal
bars with the slotted wheels attached and set them aside.
If you choose to, mount a DB-9 connector in the right rear corner of the
trackball. This will allow you to keep the extension cord intact. If you
don't want to do this, you can cut off the male end of the extension cord
and drill a small hole in the back to let the cable pass through.
Now on to the wiring. There are several solder pads located on the top
of the circuit board in the lower left corner. They are labeled TP1 - TP6.
There is another one labeled TP13 to the right of TP6. There is also a
resistor labeled R17 (a 10k). You will need to make connections to most
of these points and to the top of R17 (away from the edge of the board).
Using a low wattage soldering iron, make the connections from the DB-9
to the points on the circuit board as listed below. Use any small
wire (wire wrap wire is fine, but a bit small). If you have decided to
directly connect the joystick cord, you will need to figure out the color/pin
arrangement to make the correct connections.
--------------------------------------
Amiga Mouse Connector (DB 9 Female)
-------------
\ 5 4 3 2 1 / Front
\ 9 8 7 6 / View
---------
1 V pulse ----------> TP3
2 H pulse ----------> TP2
3 VQ pulse ----------> TP4
4 HQ pulse ----------> TP1
5 N/C
6 Button 1 (Left)
7 + 5 Volts ----------> To top end of R17
8 Ground ----------> TP13
9 Button 2 (Right)
[Remember the pin numbers are switched left to right when viewing from the
rear of the connector!]
------------------------------------------------
The buttons as supplied are wired together. You will need to cut the red
wire on the right hand switch at a distance long enough to reach pin 9 on
the DB-9. The other end of the wire will be connected to pin 6. If you are
going to remove the original cable, you will also need to make an additional
ground connection from the black wire to pin 8 on the DB-9 or to TP13 which
ever is easier.
This concludes the wiring. Make sure all your connection are secure and
that there are no shorts. Also make sure that the wires will not interfere
with the movement of the ball or slotted disks.
Put the metal bars and ball back in the trackball. Power up your amiga and
plug the trak-mouse in. If anything strange happens, remove the cable
IMMEDIATELY and verify your wiring. The only really damaging mistake is to
make the wrong connections to either the +5 or ground. If everything is ok,
put the top on & screw it back together. Have fun with your new Trak-Mouse!
[It goes without saying that none of you would ever plug both cables into
two machines at once.... Right? You Betcha!]
Mark Spankus
University of Wisconsin - Madison
Computer Science Systems Lab
path: ...!{allegra,heurikon,ihnp4,seismo,ucbvax,uwm-evax}!uwvax!mark
arpa: mark@speedy.cs.wisc.edu
Mark Spankus
University of Wisconsin - Madison
Computer Science Systems Lab
path: ...!{allegra,heurikon,ihnp4,seismo,ucbvax,uwm-evax}!uwvax!mark
arpa: mark@speedy.cs.wisc.edu
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Mike Wilkins (mwilkins@mmug.edgar.mn.org)
UUCP: ...jhereg!tcnet!vware!edgar!mmug!mwilkins
FidoNet: 1:282/55.3 - Mike's Diner BBS
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