This article will discuss how I converted a WICO trackball into a proportional input device by installing the logic board from a Commodore 1351 mouse. In doing so it was necessary to totally destroy the mouse. Irreversibly.
My inspiration for this hardware modification was an article in AHOY! several years ago by Morton Kevelson about turning the WICO into a mouse compatible unit for the Amiga. The main difference between the Amiga mouse and the 1351 is that the Amiga handles the signal interpretation in software inside the computer, while the 1351 has a custom chip that does all this inside the mouse itself. (I spent several frustrating hours on the phone tracking down that chip, but apparently Commodore designed the chip, ordered it from GTE Microproducts and bought the entire output. So GTE had no more chips and of course nobody at Commodore knew anything about them. That probably means the imminent death of the 1351 when they run out of chips. Thank goodness for the Contriver M-3!) Mort's article described a simple circuit board to replace the one inside the WICO to allow the Amiga to receive recognizable signals. The important information for me was a pinout of the connector inside the trackball. (see Table 1.)
The mouse is very easy to open: remove the two screws from the bottom, separate the top and bottom of the shell and remove the two screws that hold the pushbutton assembly., and the main mounting screw next to the ball. The WICO is even easier: there are six screws on the bottom of the case. But take care when removing them to hold the top of the case in place until you turn it upright again. The ball and the optic sensor rollers could fall out, and you might never be able to figure out how they go back in.
I opened up my 1351 and traced out the connections inside. I decided to eliminate the entire opto-mechanical portion of the mouse and use those components within the WICO. I also traced out the connectors coming into the 1351 and made note of the colors involved. (See Table 2.) The most important traces were the ones from the two sets of sensing wheels, one set for horizontal movement and the other for vertical. Each set has ground and +5VDC connections and outputs to two separate pins on the custom IC chip.
The two sensor boards attached to the rollers in the WICO have four wires leading away to a white 11 pin connector attached to the WICO logic board. You can disconnect this plug and set the logic board aside. Some WICO units may also have their own power supplies that plug into a mini jack in the back of the case. You can remove this jack as well. My WICO had its own 5 volt power but I decided that since the 1351 worked off the Commodore's internal 5 volts, and the resistors in the sensor circuits were lower ratings than the ones in the 1351's sensors that I could dispense with the external power supply.
Also, it seems that there are more than one board layout inside the 1351. I've seen pictures (in TC-128) of mouse anatomy and mine was different. In mine the custom chip ran transverse (left to right) across the width of the circuit board. Others may be different. However, I was able to cut the circuit board down to just the right size and shape to fit the holder tabs inside the WICO, so it would be stable inside the machine. (I used a "nibbling" tool from Radio Shack. It's meant to be used on a sheet metal chassis but works fine on circuit boards.) Also, I was lucky enough to find a "header" at a local electronics junk shop that fit the 11 pin plug inside the WICO. If you can't find something similar, you might remove the one from the WICO's circuit board or hard wire your connections.
Table three shows the connections I used from the mouse cord, the connector and the internal points on the 1351 circuit board. This wiring table is entirely dependent on the layout and chip used in your 1351. You should follow the traces on the main circuit board and be sure that the ones from the two optical sensors and the right button all go to the same pins on the IC chip as mine did. Since you are going to cut this part of the board off anyway, you may want to use a fine point marking pen to do your tracing. The lead that goes from the sensor to a resistor leads to ground: don't worry about it, we're going to use the resistor on the optical boards of the WICO instead.
Once you have checked and made note of the co
Once you have checked and made note of the connections to the 1351 circuit board and chip, you're ready to cut the board down to fit inside the WICO case.
The first step is to remove the ball & sensor module which is attached by 16 pins (eight each sensor) to the board. I used de-soldering braid from Radio Shack.
Use the original WICO board as a guide. On the one I used, there was a square notch along the bottom that fit into a slot on the bottom of the case. I was able to cut a corresponding notchin the 1351 board. If you don't have a nibbling tool, a good way to cut the board is to score it deeply along the drsired line ON BOTH SIDES and then snap on the line by cutting on it with a sharp pair of wire cutters. Of course you will be cutting through the traces that lead from the optical sensors, but that's why we're going to solder directly to the chip.
By now you should have noticed that there is a trace all the way around the board that is GROUND. It is atached to the white wire coming in from the computer cable, and lots of components are attached to this bus trace. I used one of the legs of a resistor that attached to the GROUND buss on the underside of the board for my ground connection to the 11 pin connector. The same holds true for the +5VDC line.
You should be careful in soldering the connections to the IC chip, not to overheat the chip. Use a low powered iron and tin the wire and the leg on the chip first. Then use just enough heat to stick the wire to the leg of the chip. You don't want to get this far and then fry the 1351's central nervous system with too much heat!
The one thing I didn't make note of was exactly which pin on the IC was exactly which for Vertical 1 & 2 and Horizontal 1 & 2. I do know I had to switch one of them, but whether this got onto my final table, I'm not sure. Therefore, you should, after wiring everything up, leaving the track ball case open, lay the ball on top of the rollers, plug it in to Joystick port 1, and boot GEOS or some other program that supports the proportional mouse. You will know immediately whether you have the connections correct or reversed by the way the pointer responds. If it goes right when you roll the ball left (or up when you roll down) you have reversed the "1" and "2". When all is well, shut down the computer and close up the trackball case.
I used just one additional pushbutton (Radio Shack # 275-1566) for the right mouse button, installed to the right of the built in button, and wired to ground and pin 5 of the IC chip.
I found that the setup of the buttons was less than ergonomically perfect. I have to lift my hand from the ball to hit the left (built in) button. It might be better to replace that one with a new button on the SIDE of the WICO case where your thumb rests.
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Table 1. Internal WICO connections:
WIRE COLOR FUNCTION
T1 White Left Button
T2 Red +5Volt Vertical
T3 Red +5Volt Horizontal
T4 White Left Button
T5 Black Ground Horizontal
T6 Black Ground Vertical
T7 (No Connection)
T8 Purple Vertical #1
T9 Blue Vertical #2
T10 Green Horizontal #1
T11 Yellow Horizontal #2 _
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Table #2 Wires Into 1351 (these are the only ones you need)
Pin Color Function
6 Blue Left Button
7 Purple +5Volt
8 White Ground
(All wires stay connected to the 1351 circuit board. This is just so you know where to find the line you need)
Table #3 Hybrid Connections
WICO Pi
Table #3 Hybrid Connections
WICO Pin Color 1351 Connection (Color)
T1 White Left Button (Blue)
/Red +5Volts (Purple)
T3) / \Red +5Volts (Purple)
T4)\ /(White) (Left Button)
T5) |--- |Black Ground (White)
T6)/ \Black Ground (White) Note T4,5 &6 ALL Grd)
T7 (No Connection)
T8 Purple Vert #1 (IC Pin 3)
T9 Blue Vert #2 (IC Pin 4)
T10 Green Horz #1 (IC Pin 1)
T11 Yellow Horz #2 (IC Pin 2)
Right Button IC Pin 5
Ground
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That about does it. Enjoy. If you have any questions, E-mail me. I'm known as Jacquot on Q-Link. Or you can write me at the following address:
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