emulator: fixNES
type: libretro
core_classification: official_port
source: "https://github.com/libretro/fixNES"
upstream: "https://github.com/FIX94/fixNES"
profiled_date: "2026-03-23"
core_version: "Alpha v1.3.1"
display_name: "Nintendo - NES / Famicom (fixNES)"
cores:
  - fixnes
systems:
  - nintendo-nes
  - nintendo-fds

notes: |
  fixNES is an NES/Famicom emulator by FIX94 (same author as fixGB).

  FDS games require disksys.rom (8192 bytes) in the system directory.
  mapperInitFDS() in mapper.c:87-110 opens the file, validates exact
  size 0x2000, reads into fdsBIOS[]. Returns false if missing or wrong
  size. No hash validation.

  Regular NES/NSF games need no BIOS.

  No other system files loaded. system_dir accessed only for disksys.rom
  (libretro/libretro.c:277-285, doOpenFDSBIOS).

files:
  - name: "disksys.rom"
    description: "Family Computer Disk System BIOS"
    system: nintendo-fds
    required: true
    mode: both
    size: 8192
    validation: [size]
    source_ref: "mapper.c:87-110 (mapperInitFDS), libretro/libretro.c:277-285 (doOpenFDSBIOS)"