After building [chippy](https://github.com/bradford-hamilton/chippy), I wanted finding something a little more challenging. I really enjoyed it so I'm going to give an Apple 1 computer a shot.

Current references:
- [6502 instruction set](https://www.masswerk.at/6502/6502_instruction_set.html)
- [6502 memory test](http://www.willegal.net/appleii/6502mem.htm)
- [6502 instructions description with undocumented commands](http://www.zimmers.net/anonftp/pub/cbm/documents/chipdata/64doc)
- [a rust implementation](https://github.com/alexander-akhmetov/mos6502)