Gene Hesketts notes on making a _cheap_ PC mouse work on the Amiga. Preface: If this modifcation causes a divorce, or warts, or your dog bites the postman again, or your Amiga goes up in copious clouds of smoke, I am not responsible. This is 100% your baby! I am going to assume that you are familiar with modern soldering technics, and not belabor the choice of irons and tools to use. Simply said, if you weren't born with a hot soldering iron in one hand, then this is NOT a project for you. I've been doing this stuff for a living since the late 40's, so I guess that makes me a genuine old fart! 1. Get the generic, approximately $15 at Office Max, Logitek DeXxa 3 button serial mouse, model #3B MSE 930265-00 or its el cheepo replacement. I have found from about 3 years use of this mouse, that its usually quite smooth in operation, requireing considerably less cleaning and tweeking to keep it moving accurately. 2. On your way back from Office Max or ???, stop in at Toys R US, and get a 9 pin gamepad extension cord, the one I just got was a 7 footer and cost about $3.50 or so. 3. Open up the mouse, and remove the cable plug from the board, tossing that cable in your "spares for pc's" box as it doesn't have near enough wires in it to work on an Amiga, which if you are gonna use all 3 buttons, takes all 9 pins in the plug. 4. Remove the socket where that cable was plugged in. 5. Clipping the legs very close to the board, remove the 16 pin integrated circuit, and clean the holes out because 7 or the wires in the gamepad cable will be inserted into the holes the IC's pins vacated. 6. Remove the chip resistor marked '470', located between the IC's 8 and 9th pin, and which is on a pad connected to pin 10 of the IC on one end, and to a runner that hits the minus pin of LD1 on the other. This is the current limiting resistor for the infrared leds that drive the motion detectors, and at 47 ohms, would smoke them quickly. 7. Form and clip the leads of a 680 ohm, 1/4 or 1/8th watt resistor so that it will lay on the bottom of the board neatly and solder to the pads vacated by the chip resistor removed in 6 above. 8. Using a short (1.5") piece of wrapping wire, connect trace that runs around the outside edge of the board using the outside hole of the cable sockets pattern on the board, over to the gap between the switches and to the bottom of the board, wrapping it around the negative lead of the small electrolytic 'c1', and taking it back thru the gap between the switches back to the top side of the board and to the hole where pin 9 of the IC was. Solder the wire where its wrapped around that bit of cap lead sticking out of the bottom of the board. 9. Now, cut the male end of the gamepad cable off a few inches from the plug, and remove about an inch of its outer jacket. 10. Verify that the black wire in the gamepad cable is indeed connected to pin 8 of the female end of this cable. If pin 8 isn't black, then you will have to make suitable corrections to the colors I will name along with the pin it belongs to. Pin 8 is the common ground for the system. I will state the color and the pin it belongs to like this: black(8) from now on. I'll also assume you are soldering as we go. 11. Insert the black(8) wire into the hole in the pcb adjacent to the J1 marking where you removed the cable socket. 12. Insert the red(7) wire into the pcb hole where pin 13 of the IC was. This is directly below the slender gap between the 'left' and 'middle' switches. 13. Insert the yellow(5) wire into the IC's hole pattern at pin 11. 14. insert the white(1) wire into the IC's hole pattern at pin 8. 15. Insert the green(3) wire into the IC's hole pattern at pin 7. 16. Insert the blue(2) wire into the IC's hole pattern at pin 6. 17. Insert the brown(4) wire into the IC's hole pattern at pin 5. 18. Insert the grey(9) wire into the IC's hole patern at pin 3. 19. Insert the orange(6) wire into the IC's hole pattern at pin 2. 20. Double check everything. 21. Plug it into the second db9 on the machine, turn it on and measure the voltage at the plus side of c1, using the minus side or the machines grounded case as the point to place the black probe, which should be 5 volts plus or minus whatever your supplies 5 volt tolerance is. 22. Check the voltage from c1's negative terminal to the ends of the 680 ohm resistor installed clear back up at step 7. You should find ground on one end, and about 2.65 volts on the other. This would indicate that there is some current flowing thru the ir led's. 23. If these check out, mash the game cable down into the gap between the middle and right switches so that its laying as the original but somewhat smaller cable was. Set the pcb back into the bottom half of the shell and mash the cable into the strain relief notches molded into it. Press down on the top of the shell enough to get the rear half into place. Put the screws in and tighten. Then using a smaller jewellers screwdriver, reach into the area under the outside buttons and press until the clips finally catch to hold the front of the top shell on. The larger size of the game cable makes this a bit more difficult obviously. 24. Plug it in and check it out! Background: The average pc mouse sets new standards for being miserly with power. It turns out that not only does the typical mouse sleep 99% of the time unless moving, it also strobes the ir leds at a high audio rate in order to get enough light for the sensors without sucking the power way down. Remember, these things actuall run on the milliamp or so from a couple of the usual rs-232 signal lines! This modification sends a steady current thru the led's, wires the switches for steady power which the amiga has plenty of, and send the photo detector outputs directly to the amiga. I experimented some with the led current, and got good operation when the resistor was adjusted to the 1000 ohm end of its range, a very miniscule (2.5 milliamps) amount of current for an led I think since the two of them are in series with themselves and the changed resistor across the 5 volt line now. So I gave it about 3.5 mills and called it good. I can imagine that some mice's led's might need as low as a 220 where the 680 I used goes. 25. This has been tried on 2 different A2k's both running ados 3.1. This machine, when running a swifty 3 button, has always been slow, making me turn on MCX's mouse acceleration to 3 or 4. Now its turned off and just right. On my office machine, its quite a bit faster. As this is a function of the conversion chips in the amiga, there isn't much I can do to slow it down there, except take my old swifty to work! 26. Author: Gene Heskett, aka 27. Have fun folks! Thats what this is all about.