Cheap 65C02 chips from Ali Express

[ceptimus]

I'm building some new Picocomputers, and took a chance on a lot of 5 off W65C02S8P-10 chips from an Ali seller. The extra number under the main one is SA1034A on mine.

They work, but not at full speed. All are okay at PHI2: 2000 kHz, a couple work up to 3200 kHz. None work at 4000 kHz. When I try to push them faster than they want to run, I get a ?watchdog timeout when attempting to load a .rp6502 file, or, on a couple of occasions when I've been at the 'bleeding edge' speed, a lock up while the 6502 program is running.

The same Picocomputer I've tested them on runs reliably up to PHI2: 8000 kHz with a W65C02S6TPG-14 I bought from Mouser.

From an online search, I found that the W65C02S8P-10 chips are supposed to be able to run up to 10 MHz, but it's possible that there's something about their timing that stops them working much above 2 MHz on the Picocomputer. Or maybe my chips are fake or rejects - I knew I was taking a chance when I bought them, but they were cheap! :)

I also ordered a lot of five cheap W65C22S VIA chips from Ali, but they've not arrived yet. I'll test those out, if, and when, they arrive.

[rumbledethumps]

Tons of 1, 2 and 4MHz 65C02 were made back in the day. Sounds like you got some blacktopped or maybe an old counterfeit batch surfaced.

On the plus side, you can now save a few cents on the 74xx parts since they don't need to support 8MHz.