emulator: RustyNES
type: libretro
core_classification: official_port
source: "https://github.com/doublegate/RustyNES"
upstream: "https://github.com/doublegate/RustyNES"
profiled_date: "2026-10-26"
source_commit: "3d02b99dc84fb389c03fc6b1f986ffa658dda0dd"
core_version: "3.5.0"
version_basis:
  kind: file
  path: "Cargo.toml"
  pattern: 'version\s+=\s+"([^"]+)'
display_name: "Nintendo - NES / Famicom (RustyNES)"
cores:
  - rustynes
systems:
  - nintendo-nes
  - nintendo-fds

notes: |
  RustyNES is a NES and Famicom emulator written in Rust by DoubleGate.
  The libretro core is the crates/rustynes-libretro crate of the same
  repository, built from the main branch
  (crates/rustynes-libretro/Makefile, .gitlab-ci.yml). The crate pulls
  rustynes-core with default features off and does not link the
  rustynes-hdpack crate, so no HD pack is read. The game database it links
  is compiled in (crates/rustynes-gamedb/src/lib.rs:41), and its
  game_db_user.txt overlay is read only once a host sets its directory,
  which the libretro crate never does (crates/rustynes-gamedb/src/lib.rs:356-366).

  Cartridge content needs no external file. Content is a Famicom Disk System
  image when its path ends in .fds or its bytes open with the fwNES header or
  the *NINTENDO-HVC* side marker (crates/rustynes-libretro/src/lib.rs:2225-2244).
  Such an image goes to Nes::from_disk, which needs the Famicom Disk System
  BIOS: the core joins disksys.rom to the frontend system directory and reads
  the whole file (crates/rustynes-libretro/src/lib.rs:1380-1396). A missing
  file, or a frontend without a system directory, makes retro_load_game fail
  with an error. Fds::new rejects a BIOS that is not exactly 8192 bytes
  (crates/rustynes-mappers/src/fds.rs:1368-1374). No hash is checked. The
  FDS device maps the BIOS and boots from its reset vector.

  The version comes from the workspace Cargo.toml. The .info in
  libretro-core-info says v3.4.0 and the copy in the repository v3.5.0.
  The md5 in the .info notes is not enforced by the code.

files:
  - name: "disksys.rom"
    system: nintendo-fds
    description: "Famicom Disk System BIOS"
    required: true
    size: 8192
    validation: [size]
    source_ref: "crates/rustynes-libretro/src/lib.rs:1380-1396, crates/rustynes-core/src/nes.rs:538-540, crates/rustynes-core/src/bus.rs:1103-1108, crates/rustynes-mappers/src/fds.rs:121, crates/rustynes-mappers/src/fds.rs:1368-1374"
    note: "Read only when the content is a Famicom Disk System image, by extension or signature. Any other size fails the load."