Oh! Haha, I had tried that because you made it sound possible!
The time-constant of the 0.1µF cap and 1K resistor is only 100µs, much too short for a power-on situation. My experience with can oscillators is most take several 10s of milliseconds to stabilize following power on. Roll-your-own oscillators using a crystal and associated components probably take as long, or longer than a can oscillator. WDC states in the data sheet that reset must stay low for a minimum of two full Ø2 cycles, which means the oscillator must be stable before reset is released. I dunno about the 65C02, but I can tell you that the 65C816 will not come out of reset if that two-cycle minimum is not satisfied.
100us = 100,000ns, yes? OH, but you are saying during power-on it would take longer than that just to get power all over the board, etc. Ah ok.
Arranging the Ben Eater reset circuit so it will produce a 250 millisecond delay on power-up, but with using a more reasonable 3.3K resistor, would require a timing capacitor of approximately 70µF. That assumes the MPU sees the low-to-high transition of reset as valid around 3 volts. Resistance in series with the reset push button would be de rigueur to limit the capacitor discharge current to a safe level when manually resetting the machine.
Oh that's a MUCH bigger capacitor. I'm ok without all of that.
Well, good info here, I'm learning. And I've learned that the MCP130xxxD is perfectly fine for my needs. It's a 'drop in replacement' for the DS1813 (with my particular board's setup) yet cheaper. Thank you BDD, I appreciate learning from you.
Chad
