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Atari Trackball to Amiga Conversion ----------------------------------- By John H. Lee (jhlee@hac2arpa.hac.com) Copyright 1995 by John H. Lee. All Rights Reserved. NOTICE ------ Permission to freely redistribute this file is hereby granted provided that it is redistributed in its entirety. The author assumes no liability for any damage or injury resulting from use of or following of directions in this document. USE AT YOUR OWN RISK. This file documents how to convert Atari model CX22 and CX80 trackballs (originally manufactured for the Atari Video Computer System(TM) and Atari home computers) for use on Commodore Amiga computers. I've encountered at least two different Atari trackballs: the model CX22 and model CX80. The model CX22 has a beige trackball and two round buttons. The model CX80 has a black trackball and twp triangular buttons. The CX22 appears to be the original model while the CX80 is the newer cost-reduced model. They are functionally identical with somewhat similar circuit designs. Their construction differ considerably, but both can be converted into Amiga trackballs while preserving their switchable trackball and joystick modes. Atari CX22 Trackball Conversion (Round Buttons & Beige Trackball) ----------------------------------------------------------------- Theory of Conversion: The CX22 trackball generates quadrature signals from vertical and horizontal optical interrupters just like an Amiga mouse. A LM339C quad op-amp IC is used as a quad comparator to clean up the signals from the optical pickups. A 4538 (dual D-flip-flop) and a 4011 (quad 2-input NAND) IC take the quadrature signals and generate four direction signals: left, right, up, and down. The four direction signals, the vertical pulse signal, and horizontal pulse signals are fed into a 4019 (quad AND/OR selector) IC that selects between the joystick signals and the Atari mouse velocity & direction signals. The conversion works by replacing the Atari mouse signals at the 4019 selector IC with the quadrature signals from the comparator. The Atari joystick signals are the same as the Amiga's. If desired, the right trackball button is separated from the left button and turned into Mouse Button 3 (the right mouse button). Some games also recognize it as a second joystick button. Parts Needed: 9-pin cable with female DB9 connector (if a right-mouse button is desired) Parts to connect the 9-pin cable (heatshrink tubing for insulating splices or 6 crimp terminals for a .100"-center Molex-type housing) Hookup wire Tools Needed: #2 Phillips screwdriver Anti-static wriststrap IC puller Needle nose pliers Ohmmeter Soldering iron Solder 1. Remove the four screws from the corners on the underside of the case. 2. Carefully pry apart the two halves of the shell, which are held together by two pressure-fit posts. They might be tight, so be patient. You might want to try pushing on the post with a screwdriver through what look like two screw holes in the bottom shell. Be careful not to drop the freed trackball on your foot. 3. Remove the two interrupter shafts and bearings. 4. Remove the two screws that hold down the printed circuit board and carefully disengage the plastic hook that holds down the corner. 5. Lift up the PCB and unplug the cable connector J1. 6. Remove the PCB from the shell. 7. Take anti-static precautions and locate the 16-pin IC marked "A5" on the PCB (a 4019) on the left side of the PCB. Carefully remove IC A5 from its socket, noting the orientation of the IC (look for the dot at pin 1 or the notch at one end.) 8. Carefully straighten pins 1, 3, 5, and 7 so that they stick straight out to the side of the IC. Dual In-Line Package IC Pin Numbering (looking from COMPONENT side at a 16-pin IC): --------------------------------------------- Dot---\ v------Notch +-U-+ 1 |o | 16 2 | | 15 3 | | 14 4 | | 13 5 | | 12 6 | | 11 7 | | 10 8 | | 9 +---+ 9. Reinsert IC A5 into its socket, making sure it's oriented correctly. 10. Solder the following jumper wires directly to IC A5 from the test points marked "TPx" placed along the bottom of the PCB. Be careful to avoid overheating the IC. IC A5 Pin Test Point Which Is Connected To (for reference) --------- ---------- ------------------------------------- 1 TP3 IC A1 pin 13 3 TP2 IC A1 pin 1 5 TP4 IC A1 pin 14 7 TP1 IC A1 pin 2 11. Unfortunately, the original cable does not connect pin 9, so it cannot support a right mouse button. If you don't want the right mouse button, you can leave the original cable and skip to step 16. 12. Replace the original cable with the new 9-pin cable. Connect the following pins from the female DB9 cable to connector J1. I reused the J1 connector shell from the original cable and installed new crimp-on terminals purchased from an electronics store. You may find it easier to cut the wires, leaving about 2" to splice the connector onto the new cable (don't cut the black ground wire to the buttons!) I highly recommend heat-shrink tubing to seal the splices; electrical tape *will* come apart, permitting shorts to occur. DB9 Pin J1 Pin Used For ------- ------ -------- 1 4 Mouse Vertical / Forward 2 3 Mouse Horizontal / Back 3 6 Vertical Quadrature / Left 4 5 Horiz. Quadrature / Right 5 (not connected) Mouse Button 2 (Middle) / Horiz. Pot 6 (Left Button) Mouse Button 1 (Left) / Fire 7 2 +5 8 1 Ground 9 (Right Button) Mouse Button 3 (Right) / Vertical Pot DB9 Pin Numbering (looking at the end of the female DB9): +-----------+ | 5 4 3 2 1 | \ / \9 8 7 6/ +-----+ 13. Cut the red wire that runs between the two buttons. Cut it as close as possible to the connector at the left button. 14. Splice the left button red wire to the DB9 pin 6. 15. Splice the right button red wire to the DB9 pin 9. 16. At this point, all wiring has been completed. Double check your work and make sure there are no shorts. 17. Plug connector J1 back onto the PCB. 18. Snap the PCB back into the bottom shell, but do not install the screws yet. Replace the two interrupter shafts and bearings, and place the trackball on the shafts. 19. Test the trackball while it's still disassembled. Set the mode select switch on the trackball to "Trackball" and plug the trackball into the mouse port of your Amiga. 20. Turn your Amiga on and verify that the mouse cursor moves and the buttons work as expected. 21. Run your favorite joystick game, move the trackball to the second mouse port if needed, switch the trackball to joystick mode, and verify the that trackball now acts like a joystick. 22. Turn your Amiga off and unplug the trackball. 23. Install the two screws that hold down the PCB. Make sure that the interrupters spin without touching the optical sensors. 24. Reassemble the shell and install the four screws in the corners. 25. Enjoy your new trackball! Atari CX80 Trackball Conversion (Triangular Buttons & Black Trackball) ---------------------------------------------------------------------- Theory of Conversion: The CX80 trackball generates quadrature signals from vertical and horizontal optical interrupters just like the Amiga mouse. Two-thirds of a 40106 (hex Schmitt-trigger inverter) IC is used as a quad comparator to clean up the signals from the optical sensors. A 4098 (dual precision retriggerable monostable multivibrator), 4013 (dual D-flip-flop), and remaining one-third of the 40106 IC take the quadrature signals and generate four direction signals, left, right, up, and down. The four direction signals, the vertical pulse, and horizontal pulse signals are fed into a 4019 (quad AND/OR selector) IC that selects between the joystick signals and the Atari mouse velocity & direction signals. The conversion works by replacing the Atari mouse signals at the 4019 selector IC with the quadrature signals from the 40106 hex inverter. The Atari joystick signals are the same as the Amiga's. If desired, the right trackball button is separated from the left button and turned into Mouse Button 3 (the right mouse button). Some games also recognize it as a second joystick button. Parts Needed: 9-pin cable with female DB9 connector (if a right-mouse button is desired) Heatshrink tubing (for insulating splices) Hookup wire Tools Needed: Anti-static wriststrap #1 Phillips screwdriver Needle-nose pliers Soldering iron Solder X-acto knife 1. Peel off the four stick-on rubber feet on the underside of the case. 2. Remove the four screws hidden by the feet. 3. Open the shell. Be careful not to drop the loose trackball on your foot. 4. Take anti-static precautions. The main printed circuit board is attached to two small circuit boards by ribbon cable. These small PCBs hold the optical sensors for the vertical and horizontal interrupters. They are slid into place and held by friction. Carefully pry up and loosen them. 5. Carefully lift the PCB assembly from the bottom shell. Do not disconnect the cable yet. 6. There are four IC's on the PCB. Looking at the component side of the PCB with the connectors to the cable at top, locate the 4019 (16 pin) and 4013 (14 pin) IC's on the right side of the PCB. 7. Turn the PCB over and on the solder side locate the solder pads for the 4013 and 4019 IC's. 8. Using a sharp Xacto knife, cut the traces to the 4019 IC at pins 4, 6, and 15. Be sure to cut only the traces to those pins. Pin 1 is marked with a small "1". Remember that the left and right sides are reversed when you're looking at the solder side. My favorite technique is to make two cuts close to each other and then lift (or scrape) the copper sliver between the cuts away from the PCB. Dual In-Line Package IC Pin Numbering (looking from COMPONENT side at a 16-pin IC): --------------------------------------------- Dot---\ v------Notch +-U-+ 1 |o | 16 2 | | 15 3 | | 14 4 | | 13 5 | | 12 6 | | 11 7 | | 10 8 | | 9 +---+ 9. Verify with a ohmmeter that the traces have been cut. 10. Solder the following jumpers from the pads of the 4013 IC to the pads of the 4019 IC. Use short pieces of hookup wire; 30-gauge wire-wrap wire works pretty well. Be careful not to overhead the IC's. 4013 IC Pin 4019 IC Pin ----------- ----------- 3 6 9 15 11 4 11. Unfortunately, the original cable does not connect pin 9, so it cannot support a right mouse button. If you don't want the right mouse button, you can leave the original cable and skip to step 15. 12. Locate the contact area for the right button on the PCB. There is a trace that goes to the "BLUE" connector via a solder pad for a jumper to the left button. Cut this trace between the right button contact area and the first solder pad, near the solder pad. The wire to pin 9 of the DB9 cable will be soldered directly to the trace leading to the contact area. 13. Replace the original cable with the new 9-pin cable. Connect the following pins from the female DB9 cable to the connector pads along the top edge of the PCB. You'll probably want to solder the new cable directly to the pads. Optionally, you can cut off the spade connectors from the original cable and splice them to the new cable. (I couldn't find substitute spade connectors.) I highly recommend heat-shrink tubing to seal the splices; electrical tape *will* come apart, possibly permitting shorts to occur. DB9 Pin PCB Pad Used For ------- ------ -------- 1 Brown Mouse Vertical/Forward 2 Red Mouse Horizontal/Back 3 Orange Vertical Quadrature/Left 4 Yellow Horiz. Quadrature/Right 5 (not connected) Mouse Button 2 (Middle)/Horiz. Pot 6 Blue Mouse Button 1 (Left)/Fire 7 Purple +5 8 Gray Ground 9 (Right Button) Mouse Button 3 (Right)/Vertical Pot DB9 Pin Numbering (looking at the end the female DB9): +-----------+ | 5 4 3 2 1 | \ / \9 8 7 6/ +-----+ 14. Scrape the oxidation off the trace to the right button and solder the wire to the DB9 pin 9 directly to the PCB trace leading to the right button. 15. At this point, all wiring has been completed. Double check your work and make sure there are no shorts. 16. Reinsert the optical sensor PCB's back into their slots. Make sure they're fully inserted and that the interrupters spin without touching the optical sensors. 17. Position the PCB back into the bottom shell and place the trackball on the interrupter shafts. 18. Fit the top shell back on and install only two screws, in diagonally opposite corners. 19. Test the trackball while it's still partially disassembled. Set the mode select switch on the trackball to "TB" and plug the trackball into the mouse port of your Amiga. 20. Turn your Amiga on and verify that the mouse cursor moves and the buttons work as expected. 21. Run your favorite joystick game, move the trackball to the second mouse port if needed, switch the trackball to "JS" mode, and verify the that trackball now acts like a joystick. 22. Turn your Amiga off and unplug the trackball. 23. Install the remaining two screws into the shell. 24. Stick the four rubber feet back over the screw holes. 25. Enjoy your new trackball! --------------- Copyright 1995 by John H. Lee. All Rights Reserved. All trademarks are the property of the respective trademark owners.