Klaus Dorman's functional tests for the 6502 are fantastic: https://github.com/Klaus2m5/6502_65C02_functional_tests


I am unaware of any formalised test suite for either the 6520 or 6522. The 6526 is at least partially covered by Wolfgang Lorenz's C64 test suite. Because of the applicability to other machines, you usually see it documented for its 6502 tests (and the outward link to the suite itself there is broken; instead try that listed here) but it includes a ...

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