You might also want floooh's remix which has a nicer UI, with the ability to see instructions evaluated, modify memory, assemble/disassemble code, view traces, etc.
This is going to sound quaint, but because of this simulation, this is the first time I realized they're _literal_ flags on the sides of the CPU, which is blowing my mind.
Unless they are hooked directly to little Swiss clock figurines holding semaphores. At that point you’d kinda have the amazing human CPU from Three Body Problem.
Visual 6502 remix: https://floooh.github.io/visual6502remix/ Visual Z80 remix: https://floooh.github.io/visualz80remix/