I know this sounds like nitpicking, but that mistake right there has caused many a 6502 emulators to produce erroneous results. The 6502 core's status register is resident and the flags in it are changed only when an op-code directly does so; it never "resets" arbitrarily, so proper conditionals that act on a specific status flag can actually occur far and wide between the op-code that actually affected that one specific flag.