visual6502

Alternatively it's fairly trivial today to run a transistor-level simulation of the 6502 (and a couple of other chips) thanks to the visual6502 reverse engineering effort (the http: link is intended): http://visual6502.org/ The netlist is available in their Git repo: https://github.com/trebonian/visual6502 ...and there's a C port of the netlist simulation code: https://github.com/mist64/perfect6502 One advantage of this approach is that you can inspect internal chip state that isn't visible on the output pins, which is very useful for emulator coding. ...and a couple of years ago I glued all those bits and pieces together for a 'remix' of the original visual6502 web application, using WASM + WebGL + Dear Imgui: https://floooh.github.io/visual6502remix/

To give proper credit (I think it's also mentioned in the blog post), the Z80 netlist was actually extracted by the visual6502 project. The data files are available in the visual6502 github repository: https://github.com/trebonian/visual6502

Here’s the source code (or at least comments about the assembled op codes) to the example program: https://github.com/trebonian/visual6502/blob/master/testprog... It looks like that subroutine they call at $0010 has a special hook that writes to the console whenever they write to memory address $0f.

I very much doubt it's a reference to anything. It doesn't appear to have a useful purpose besides demonstrating/exercising a few of the important components of the processor: it performs operations using the registers, the stack (JSR/RTS), memory (INC), and the ALU (ADC). A quick search through GitHub shows that this code is unchanged since the initial commit of the original Visual6502: https://github.com/trebonian/visual6502/blob/4d8da5b680216dc...

GitHub repository: https://github.com/trebonian/visual6502