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65c02-SIM Wiki

Welcome to the wiki for the 65c02 emulator for Ben Eater's memory layout.

What is this project?

This project is a full emulator of the WDC 65C02 microprocessor (the CMOS variant of the classic MOS Technology 6502), designed around the memory layout used in Ben Eater's 65c02 projects. It includes a modern ImGui-based graphical interface and a complete SDK toolchain for developing software that runs on the emulator.

Emulated components

Component Description
CPU Full WDC 65C02 processor
RAM 32 KB of random-access memory (0x0000–0x7FFF)
ROM 32 KB of read-only memory (0x8000–0xFFFF)
VIA MOS 6522 Versatile Interface Adapter (timers, I/O)
ACIA MOS 6551 Asynchronous Communications Interface (serial)
GPU Custom graphics controller with 7.5 KB of VRAM
SID Sound synthesis chip (3 oscillators + ADSR)
LCD 2×16 character LCD display

General architecture

┌──────────────────────────────────────────────────────┐
│              SIM_65C02 (Main Executable)             │
├──────────────────────────────────────────────────────┤
│                  Frontend / GUI                      │
│     ImGui · SDL3 · OpenGL 3.3 · ImGuiFileDialog      │
├──────────────────────────────────────────────────────┤
│                   Control Layer                      │
│           AppState · Console · UpdateChecker         │
├──────────────────────────────────────────────────────┤
│           65c02_core Static Library                  │
│  ┌───────────┬────────────┬──────────────────────┐   │
│  │  CPU      │  Memory    │  Peripherals         │   │
│  │ (65c02)   │ (RAM+ROM)  │  VIA · ACIA · LCD    │   │
│  ├───────────┼────────────┼──────────────────────┤   │
│  │     GPU (VRAM 7.5 KB)  │  SID (synthesis)     │   │
│  └───────────┴────────────┴──────────────────────┘   │
├──────────────────────────────────────────────────────┤
│               SDK / Tools                            │
│   compile-bin.sh · image-to-bin.sh · midi-to-bin.sh  │
│     Linker configs · BIOS · Microsoft BASIC          │
├──────────────────────────────────────────────────────┤
│            Example Programs & Tests                  │
│    Binaries/ (C + ASM)  ·  UnitTests/ (Google Test)  │
└──────────────────────────────────────────────────────┘

Wiki page map

  • Hardware & emulation
    • Hardware — Main emulator orchestrator and memory system
    • CPU — 65c02 processor and registers
    • CPU Instructions — Full instruction set reference
    • GPU — Graphics processor and VRAM
    • SID — Sound synthesis
    • VIA and ACIA — I/O chips
    • LCD — LCD display
    • Save States — Serializing emulator state to binary files
  • User interface
    • Frontend — ImGui windows and controls
  • Development & SDK
  • Building & testing

Quick start

Run the simulator (pre-compiled binaries)

  1. Download the latest release from the releases page.
  2. Also download SDK.zip if you want to develop programs.
  3. Open the simulator and select the .bin file you want to run.

Compile a program from the SDK

# Compile a C or assembly program
./compile-bin.sh <program_name>

# Convert an image to VRAM format
./image-to-bin.sh <image>

# Convert a MIDI file to SID assembly code
./midi-to-bin.sh <midi_file>

See the SDK page for more details.

License

The emulator C++ source code is licensed under the MIT License.
The project includes Microsoft BASIC (© 1977 Microsoft) and WozMon (© 1976 Apple Computer, Inc.) for educational purposes.

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