Hello everyone, I never thought to do anything related to the 6502, I always used the Z-?? in the 80's (It should be forbidden to mention it), but now I am delighted to discover the 6502. I recently bought a KIM Uno (Obsolescence Guaranteed) kit and then the PAL-1 Replica.
I'm now working on the KIM-1 Ruler (#KIM1Ruler on Twitter) a version of the KIM Uno (non-profit project).
I just signed up for this forum because I think I will need some help and feedback as the project progresses.
regards.

Very nice! I like handheld computing, and I like embedded emulation. I don't have a slide rule holster, but if I did, and if I wore it all the time, I might like to replace the slide rule with the KIM rule.

I do have a question: is the keyboard debouncing handled at the arduino level, or at the 6502 level?

As far as I could understand:
exec6502() , scanKeys() and Serial.available() are executed regularly in the Arduino loop().
The CPU emulation exec6502() executes 100 instructions each time is called.
The key debounce time is associated with the duration of this main loop.

New key inputs can come from the keypad or the serial port.
In the 6502 cpu emulation:
- Any read memory to the GETKEY address (0x1F6A in the KIM monitor) is intercepted to check for a new key.
- Also, any read to the keyboard input port address (0x1740, Port A of the 6530-002 RIOT) signals the emulation to check the keypad as the source.

In any case @oscarv is the wizard behind this.

Thanks! (It seems likely, then, that the Arduino level will deliver clean debounced keypresses to the 6502 layer.)