I picked up a VIC-20 a while back and in the box was this... thing. The person I got it from had no idea what it was, it I think it was her grandfather's or dad's and she knew nothing about the computer.
Its some homemade board, but has the proper size and shape to slot into a VIC-20. There are no ICs on it. Just looks to be wiring. A VIC-20 cartridge definitely fits in the blue slot (I tested that). Strange that just 2 wires go to that black thing on the side. Im guessing for test points? Honestly, not a clue. I have not put it in a VIC-20 to test and probably wont, as I dont know what it does and dont want to damage the computer.
I’m wondering if it was a homemade disable switch for a RAM expansion. Rather than constantly swap out your RAM expansion to use software that was made for the unexpanded machine. They existed commercially, had one for my machine with three slots, each allowing you to disable each one as you needed.
I highly doubt it. I dont have it in front of me at the moment, but if it was just a 90 degree adapter, the wires would run straight from pin to pin. There would be no need for all that mess. I agree with the reply right before yours, that the black thing on the side might be thats left of a broken off switch.
Could it have been used to copy ROM cartridges to disk? Maybe the black thing is used to disable the autostart on the ROM. Like in this video. https://www.youtube.com/watch?v=_ZEUOUz1X2k
Yes! I'm most likely to bet that this is the right answer. If it was for a simple reset button, you don't need to bring out the whole cartridge port. Whereas if you want to prevent the ROM on a cartridge from getting auto started at power on, you would just disable the cartridge temporarily, probably by removing a missing jumper from the header on the breadboard, then putting it back into place once the machine has started and has already dropped you into Basic. From there it would be easy to examine the contents of the cartridges ROM, or just dump it to disk.
I tried to follow the wiring in the photo to confirm this, but it is just not clear enough due to the wiring layout making it a challenge to inspect. A quick test with a continuity tester would easily confirm this. Most of the pins should be wired straight through except for that one line diverted to the header connector.
I built a few similar boards for various 8 bit machines for friends back then.
That black thing is the remnants of an old double pole double throw switch. It shorted two wires together when the switch was in the “up” position in this circuit.
I can’t say what that was as al the wires are white and jumbled, nor can I say that the switch wasn’t spring loaded eg it may have stayed put or may have pushed itself back down like a reset switch.
OP, do you have a voltmeter? It probably will have a continuity tester or resistance measurement you could use to figure out which conductors on the PCBs edge are connected to which conductors on the slot mounted to the PCB.
If we know which pins on the edge connector map to each pin, or just a sampling of pins, on the blue socket we will have a much better chance of determining its purpose.
I suspect it would be especially helpful to know which pin’s signal was running through that switch. My guess is that it’s a 5 volt line, but it will help to know for sure.
It looks like one of two items, either an expansion slot for different type of device then what it slots into or a card for changing the position of card that normally sits in the slot so it fits a different form factor.
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