Yes, you're living at the end time - emulating the 6502 chip

jwz - Visual Transistor-level Simulation of the 6502 - in Javascript. This team use photographs of the 6502 chip to create a model of the circuits and their interactions, allowing the physical chip to be modeled ...

Visual 6502 FAQ

.... There are many excellent emulators available, but emulation is approximation. It can be extremely difficult to create an accurate emulator, because the typical approach to writing an emulator is to glean information from chip specification documents or more rarely from any chip schematics that happen to be available. This information is always incomplete and even the original chip logic schematics (also Verilog and VHDL code) can differ from what was actually built in silicon (see ECO). A disciplined emulator will capture and use traces of actual chip behavior, but it's near impossible to capture the billions of sequences of bits that a real chip gives rise to. Instead, we build a virtual chip by modeling and simulating the actual microscopic parts of a physical chip. We're interested in accurately preserving historic designs. It's archaeology for microchips.

While a multitude of people understand the instruction set for the 6502, almost no one, apart from the original designers, understands how the physical chip achieves this instruction set. The design is as elegant and sophisticated as any program written for the 6502. As digital archaeologists, we invite the current generation of hardware and software engineers to appreciate the work of the small number of designers who created the basis of everything we do today...