I realized after looking at 6522 timer example code (e.g. on Jeff Tranter's website) that I'd used the wrong values for a 10ms tick. It looks like the actual value to use for the timers is 2 less that the calculated one. So for a 1MHz system I needed to use 9998 instead of 10000 for 10ms. The example code in GitHub has been updated.

I also finally got approval to list my spare 6522 boards on Tindie. There're only 2 but I'll order another batch if there's interest. Just search for 6522.

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Blog: http://ancientcomputing.blogspot.com/
GitHub: https://github.com/ancientcomputing

Just getting back to this after a year.

I had put together some test code to generate tones from Timer 1 toggling PB7. Physically, I routed this through a reproduction of the Apple II darlington-based driver circuit.

It's funny how a year changes things. Fresher eyes found a couple of typos e.g. I kept referring to PA7 instead of PB7 in the code.

Github has been updated with corrections etc: https://github.com/ancientcomputing/rc2014/tree/master/source/6502/6522

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Blog: http://ancientcomputing.blogspot.com/
GitHub: https://github.com/ancientcomputing