The MOS 6502 Microprocessor has been around sinc 1975 and is used in many popular systems, like
the Apple II, Amiga 2600, Commodore 64 and the Nintendo Entertainment System (NES).
It features an 8-bit accumulator and ALU, two 8-bit index registers and a 16-bit memory bus, allowing the processor to access up to 64kB of memory.
I/O is mapped to memory, meaning that both RAM, ROM and I/O are addressed over the same 16-bit address bus.
Because of it's simple and elegant design and the plethora of information available about this microprocessor, the 6502 is very useful for learning and hobby projects.
The 65C02 is a updated version of the 6502. It includes some bug fixes and new instructions. The goal is for i6502 to fully support the 65C02 as well.
Although this package contains everything you need, there is not single 'emulator' program yet. The CPU, address bus and RAM components are all available to you, but documentation is still lacking.
For now, you can checkout the project, and run the tests.