Experimenting with High-Speed Chips
Last time I got a 6502 CPU fully supported in the Chiplab. You can use an in-browser assembler to write your code, then upload them to run your programs against a real 6502.
Now that the chiplab is fully working for a simple chip, its time to start adding some more interesting systems. Next up is the 2A03 CPU from the NES. Though this presents some new challenges which need to be addressed.
The first chip added is a CMOS version of the 6502. This is produced with a newer process than the original 6502which happened to use NMOS. The specifics of these two processes are not too important for now. CMOS will refer to this newer 6502, and NMOS will refer to the older original design.
One nice simplification with the CMOS version of this chip is that it supports “DC” clock frequency. Though the name is a bit of a misnomer, this means that the chip can be run with an arbitrarily slow clock signal, and the behavior will still be correct.
With a CMOS 6502 already working in the lab, you may be wondering why we should care about the older NMOS version of the same chip. The 6502 was a very popular design and instruction set at the time. Since programmers were writing primarily in assembly language, using this chip meant programmers already familiar with 6502 assembly could produce software for your system. This lead to the 6502 being used in many systems, sometimes even embedded in other chips.
