Emulation

The magic of translating the ghost of a machine into the language of another. Discover how software becomes silicon through the power of first principles.

Structured Principles
  1. PART I: THE BRAIN
    1. The Fetch-Decode-Execute Cycle
    2. Registers & Arithmetic Logic Units
  2. PART II: THE UNIVERSE
    1. Memory Mapping & Buses
    2. Bank Switching: Breaking Zero-Page
  3. PART III: THE LIGHT
    1. PPU & Scanline Rendering

The Pulse of the Machine

Every processor is a heartbeat. In each cycle, it fetches an opcode from memory, decodes what it means, and executes the logic. To emulate a CPU, we must recreate this cycle in software, often with a giant `switch` statement or a lookup table.

CPU Step-Debugger
PC: 0x8000
A: 0x00
X: 0x00
Y: 0x00

Watch how the Program Counter increments and registers change as the emulator "interprets" raw binary data.

The Geometry of Information

A CPU doesn't know what a "controller" or "screen" is. It only knows memory addresses. Through Memory-Mapped I/O, writing to a specific address like `0x2000` might actually be talking to the graphics chip. We must build a virtual "Bus" that routes data to the correct device.

Real-time Memory Map

A visualization of 64KB address space. High-speed writes simulate a running game's data flow.

Drawing with Electrons

Retro consoles didn't have "framebuffers" in the modern sense. They drew to the screen one scanline at a time, racing the electron beam of a CRT. Emulating a PPU (Picture Processing Unit) requires precise timing to match the horizontal and vertical synchronization of old displays.

Scanline Pulse Visualizer

Observe the raster beam's journey as it reconstructs an image pixel by pixel.