ahhh... the 65816 must be more strict then the W65C02S... I'm curious now... think I'll order a 65816 and see if I can get it to work on the same board.

Has anyone here tried a dual CPU system using the 6502?

Hmm, in my circuit, I had to resort to using 74F logic -- LS was just too slow (7ns rise/fall times for me). I later switched to a 4-pin metal can oscillator, and freed up a bit of space.

Maybe it had more to do with your circuit design then the 74LS switching time? Or maybe the W65C02S 5ns F&R ...

I think for learning purposes, to use a breadboard to build a simple 6502 computer is quite the right thing to do. If it works consistently, then what's the problem (which it does). We can go on and on about good practice, etc.etc... but were not trying to launch the space shuttle here... just have ...

1) NEVER think about using anything but a pre-built, all-in-one, 4-pin metal-canned clock oscilators for the CPU's clock. Anything less will be too slow for the CPU on the breadboard (each strip in the breadboard adds capacitance, and each wire, as Garth says above, adds inductance, all ...