emulator: fixGB
type: libretro
source: "https://github.com/libretro/fixGB"
profiled_date: "2026-03-18"
core_version: "Alpha v0.8.2"
display_name: "Nintendo - Game Boy / Color (fixGB)"
cores:
  - fixgb
systems:
  - nintendo-gbc

notes: |
  fixGB is a Game Boy / Game Boy Color emulator by FIX94, currently at
  alpha v0.8.1. It supports .gb, .gbc, and .gbs (Game Boy Sound) files.

  The core optionally loads "gbc_bios.bin" (CGB boot ROM) from the
  system directory. In the libretro port, doOpenCGBBootrom() in
  libretro.c:246-254 resolves the path via
  RETRO_ENVIRONMENT_GET_SYSTEM_DIRECTORY + "/gbc_bios.bin".

  memInitCGBBootrom() in mem.c:567-586 validates the file: it must be
  at least 0x900 (2304) bytes. If present, 0x900 bytes are read into
  memCGBBootrom[] and cgbBootromEnabled is set to true. The boot ROM
  plays the Game Boy Color startup animation before handing off to the
  game.

  If the file is missing or too small, the core skips the boot sequence
  and starts games directly. The BIOS is optional -- games run fine
  without it.

  Despite the core name suggesting general Game Boy support, the only
  BIOS file referenced is the GBC boot ROM. There is no DMG (original
  Game Boy) boot ROM support in the source.

files:
  # --- GBC boot ROM (optional, enables startup animation) ---
  - name: "gbc_bios.bin"
    system: nintendo-gbc
    description: "Game Boy Color (CGB-001) boot ROM"
    required: false
    hle_fallback: true
    size: 2304
    md5: "dbfce9db9deaa2567f6a84fde55f9680"
    sha1: "1293d68bf9643bc4f36954c1e80e38f39864528d"
    source_ref: "libretro/libretro.c:246-254 (doOpenCGBBootrom), mem.c:567-586 (memInitCGBBootrom)"
    notes: "Must be at least 0x900 (2304) bytes. Only the first 0x900 bytes are read. Enables cgbBootromEnabled flag for boot animation. Disabled via memDisableCGBBootrom() when register write occurs."