Step 5.2: Single-step


I wired up a single-step clock by the end of the hack-day weekend. This means that, instead of going at 1 MHz, I can clock one bit at a time.

Running the whole CPU + Flash RAM + ACIA stack: Inconclusive.

Running the whole CPU + Flash RAM + ACIA stack with the Flash in a tight loop: Why is the address line going in a weird direction? Also, why are some of the lines silent with my logic probe?

I check and the silent line is within the spec for that particular part against the Rockwell datasheet. Switch the logic probe to TTL mode and it starts to behave. But it’s going into places that it’s not supposed to be going!

Switching back to the configuration from Step 3, but single-stepping: Discover that the processor is very much not single-stepping properly anymore. Seems like somewhere along the way I managed to zap it!

It also turns out that I only picked up one 65c02, which is a really poor life choice.

Second break: Waiting for a 65c02 to appear in the mail!