rwv01 wrote: ↑Sat Apr 25, 2020 11:49 pm
Thanks for your replies.
Well, patching the F1 key to the control port would be the most practical way to do it, but I'd rather not
hack the VIC itself. If a software wedge is possible, would it work like the CardKey numeric keypad and software combination?
It is not such a great hacking issue, only a few tools are needed, such as screwdriver, knive, two wire cable, about 145 ohm resistor, soldering tools and insulating tape, since the keyboad itself has a free plug-in connection. There you could patch the keyboard cable, there is no need to touch the sacred motherboard at all.
More advanced could be to plug in a second connector with exposed prepared cable piggy back between CB connector and the keyboard connector, so that every button can be patched or reached from external.
To be on the safe side, you can use a second spare keyboard.
I did something similar a while ago. Here I patched the F1 key with an external button the first time.
At a next time, I connected a 64 buttons square custom matrix to study the behavior when more buttons pressed at time, you know, some games get cheats working that way. But this was not my principal purpose.
As you can see there are 18 lines = 8 row select + 8 column select, if you can imagine an 8x8 matrix. The leftover black and white cables are for restore key.
The green cable from the right side half from connector on following picture is the first line leading to F1 button.
The grey-white cable (near brown) starting from the left on the picture is the second line leading to F1 button.
Disconnect the keyboard connector with care. Mark both cables with an marker pen or isulating tape.
Cut the two lines you marked and prepare it to solder with the external two wires, or carefully peel the cable sheating with a cable cutter at a small point around the cable, so that the wire for connecting the external button can be reached, without cutting the cabel.
On one of this lines you should insert in serie an around 145 Ohm resistor, as in the original keyboard button I measured this value. 120 ohm should do the job too. Now solder your new key to the ends of you external cabel. Done. If you want to be sure what you have done, use an multimeter to check connections or even to be sure you have not done some shot circuit.
Connect now your patched keyboard to CB and check the software side of the matter.
0 PRINT PEEK(197):GOTO
RUN
If you get a value of 64 when no key is pressed and 39 by pressing F1 operation was successfully.
Now fix the new extension key to the joystick with super glue and have fun with your cartridge game