Building a is a classic rite of passage for systems programmers. The MOS 6502 was the brain of iconic systems like the Apple II , Commodore 64 , and NES . Its simple architecture—featuring only 56 base instructions and 6 registers—makes it one of the best CPUs to emulate for learning purposes. 1. Architecture Basics
Holds the current stack location (usually at address $0100 ). (Status Register) Stores flags: Carry, Zero, Negative, Overflow, etc.. 6502-emulator
Special high-speed memory area used like extra registers. Stack ($0100–$01FF): Fixed location for the system stack. Building a is a classic rite of passage
Locations where the CPU looks for jump addresses when it resets or receives a signal. 2. The Emulation Loop The core of your emulator is a "Fetch-Decode-Execute" loop: Emulating a CPU in C++ (6502) Special high-speed memory area used like extra registers
To start, you must define the data structures representing the CPU's internal state. Description (Program Counter) Points to the next instruction in memory. A (Accumulator) Used for all arithmetic and logic. X & Y (Index) Used for addressing offsets and loops. S (Stack Pointer)
The 6502 uses a 16-bit address bus, allowing it to address 64 KB of memory.