#c64 #8-bit #llvm-mos #6502 #mega65

nightly no-std mos-hardware

Hardware register tables and support functions for 8-bit retro computers like the Commodore 64, MEGA65 and others

11 releases

0.2.0 Mar 1, 2023
0.1.9 Aug 20, 2022
0.1.7 Jul 31, 2022

#744 in Embedded development

40 downloads per month


5.5K SLoC

Rust 3.5K SLoC // 0.1% comments C 1.5K SLoC // 0.2% comments GNU Style Assembly 290 SLoC

Crates.io docs.rs


This crate contains hardware register tables and support functions for 8-bit retro computers like the Commodore 64, Commander X16, MEGA65 and others. Please check the examples directory to see how Rust can be used to generate simple demo effects.


  • Excellent support for Rust programming on CBM (inspired) 8-bit computers
  • Labelled registers for expressive hardware programming
  • Intuitive bitflags with type checks where possible
  • Minimum resource impact


Read and write to labelled hardware registers

use mos_hardware::{c64, vic2};
let old_border_color = c64::vic2().border_color.read();
unsafe {
    c64::sid().potentiometer_x.write(3); // compile error: read-only register

Use bitflags to safely control hardware

...for example where the VIC-II chip accesses screen memory and character sets:

use mos_hardware::{c64, vic2};
let bank = vic2::ScreenBank::AT_2C00.bits() | vic2::CharsetBank::AT_2000.bits();
unsafe {

Convenience functions to perform hardware-specific tasks

...for example to generate random numbers using noise from the C64's SID chip:

use mos_hardware::c64::*;
let value = sid().random_byte();

Getting started

The project requires rust-mos and is setup to build for C64 by default. A docker image of rust-mos is available if you do not fancy compiling LLVM. If you want to start a new project which uses mos-hardware, there's a Github Template.

Docker and Visual Studio Code

The easiest way is to use the provided .devcontainer.json configuration for vscode:

  1. Configure Visual Studio Code with the Remote - Containers extension
  2. Open the project inside devcontainer when asked
  3. In the vscode terminal do:
    # if Docker uses qemu (i.e. on apple silicon)
    # build for the MEGA65:
    cargo build --target mos-mega65-none


The hardware registers are currently incomplete and the library may be subject to significant changes.

  • Commodore 64:
    • sid
    • vic2
    • cia (partially)
    • c64 memory map (particlly)
    • PSID file support for SID music
    • Random number trait (RngCore)
  • Commander X16
    • vera
    • via (partially)
    • cx16 Memory map (partially)
    • Support functions
  • MEGA65:
    • partial support for vic3, vic4 and other hardware registers.
    • mega65-libc bindings
  • Examples:
    • Plasma effect (c64, mega65)
    • Raster IRQ (c64)
    • Sprites (c64)
    • Smooth x-scrooll (c64)
    • Joystick read (c64)
    • 10print maze (c64)