I ran into this strange behavior of the BIT operation. The BIT operation does two things:


Bits 7 and 6 of operand are transfered to bit 7 and 6 of SR (N,V);
The zero-flag is set to the result of operand AND accumulator.


I'm still trying to get my emu to pass Klaus tests, and I'm running ...

Thanks BigEd, this was just the response I needed to get some confidence in how I interpret the logs and documentation! I'm sure more questions will pop up shortly!

Welcome! I'm having trouble accessing visual6502 but I have a local copy (you could download one from the Wayback Machine.) I'm not so familiar with perfect6502 - the model is fine, I'm sure, but I don't know about the inputs or the interpreting of the logs

I've compared visual6502 and ...

So I was quite happy about my 6502 emu. And then I started comparing logs with visual6502/perfect6502. Aaaand... no.

It's something about the "pipelining" that just breaks my brain. At least I think it's related to that.

For testing, I created a very small program:


start:
ldx #$02
loop:
dex ...