May be fun, a project remixing visual6502 as a Web Assembly (WASM) application:
https://floooh.github.io/visual6502remix/
Form the GitHub page (GitHub - floooh/v6502r: visual6502 remixed):
TL;DR: Take the visual6502 project and turn it into a native+wasm app via perfect6502, Dear ImGui and Sokol.
Via HN, Visual6502 Remix | Hacker News
(The single step mode is rather nice and informative. Requires a rather recent browser with WASM support.)
That’s looks good and runs fast! I still use visual6502 to explore and explain aspects of the 6502 - for example, there’s a trick to how the first byte of an absolute address is handled, and an even bigger trick for how the first byte of a subroutine call is handled.
The original visual6502 has an advantage, I think, over the present state of this remix: it can run substantial programs with I/O and without the burden of the graphics, which can be illuminating. As an unilluminating example, this program computes pi (very slowly indeed):
http://goo.gl/FXuoI