6502 simulator

This project is primarily an exercise to prepare for a more in-depth project. Inspired by modern Apple II expansion cards like the V2 Retro Computing Analog card [1], we wish to design a microcontroller-based card for future experimentation, the eventual goal being an emulated Z80 softcard. We know this is an achievable goal, but it seems prudent to try writing a PC-based CPU simulator first. We have selected the 6502 as our target for its low instruction count, simple architecture, and variety of addressing modes.

Our goals are as follows:

1. a SIMH-like console interface with memory/register editing, breakpoints, disassembler, and single-step execution
2. simulated RAM, ROM, and I/O devices with memory mapping and bank switching
3. realistic timing
4. a portable and general core
5. extensible for future GPIO operation

This is not intended to be able to simulate a full Apple II, NES, or similar 6502-based device.

• registers
• fetch-decode loop
• hold states and breakpoints

• commands
• breakpoint management
• limitations
• I/O devices