emulator: Beetle Saturn (Mednafen)
type: libretro
core: mednafen_saturn_libretro
source: "https://github.com/libretro/beetle-saturn-libretro"
profiled_date: "2026-03-18"
core_version: "v0.9.45.1"
display_name: "Sega - Saturn (Beetle Saturn)"
systems:
  - sega-saturn

notes: |
  Beetle Saturn is the libretro port of Mednafen's Sega Saturn emulation module.
  Two region-specific BIOS files are used: sega_101.bin for Japan/Asia NTSC,
  mpr-17933.bin for North America, Europe, and all other regions. The core
  returns false from InitCommon() if the BIOS file is missing or not exactly
  512 KB, so both BIOS files are required for full region coverage.

  Region auto-detection reads the disc header and picks the matching BIOS.
  Manual region override is available via beetle_saturn_region core option.

  The KOF95 and Ultraman ROM carts are optional game-specific expansion
  cartridges loaded from the system directory. The Action Replay 4M Plus
  cart (satar4mp.bin) is listed but marked unfinished in source (needs
  CPU UBC emulation).

  BIOS loading: mednafen/ss/ss.cpp InitCommon() lines 920-961.
  Cart loading: mednafen/ss/cart.cpp CART_Init() lines 128-220.
  Firmware path: libretro.cpp MDFN_MakeFName(MDFNMKF_FIRMWARE) -> system dir.
  Default cart ROM filenames: mednafen/settings.cpp MDFN_GetSettingS().

files:
  # -------------------------------------------------------
  # Saturn BIOS - Japan / Asia NTSC
  # -------------------------------------------------------
  - name: "sega_101.bin"
    system: sega-saturn
    region: [japan, asia-ntsc]
    required: true
    size: 524288  # 512 KB
    md5: "85ec9ca47d8f6807718151cbcca8b964"
    note: "Saturn BIOS v1.01 (Japan). Used when region is JP or Asia NTSC."
    source_ref: "mednafen/ss/ss.cpp:928-929"

  # -------------------------------------------------------
  # Saturn BIOS - North America / Europe / other
  # -------------------------------------------------------
  - name: "mpr-17933.bin"
    system: sega-saturn
    region: [north-america, europe, south-korea, asia-pal, brazil, latin-america]
    required: true
    size: 524288  # 512 KB
    md5: "3240872c70984b6cbfda1586cab68dbe"
    note: "Saturn BIOS (NA/EU). Used for all non-JP/Asia-NTSC regions."
    source_ref: "mednafen/ss/ss.cpp:930-931"

  # -------------------------------------------------------
  # King of Fighters '95 ROM cart
  # -------------------------------------------------------
  - name: "mpr-18811-mx.ic1"
    system: sega-saturn
    required: false
    size: 2097152  # 2 MB (0x200000, rom.cpp reads up to this)
    md5: "255113ba943c92a54facd25a10fd780c"
    note: "KOF95 expansion ROM cart. Loaded when cart type set to KOF95."
    source_ref: "mednafen/ss/cart.cpp:157-172, mednafen/settings.cpp:64-65"

  # -------------------------------------------------------
  # Ultraman ROM cart
  # -------------------------------------------------------
  - name: "mpr-19367-mx.ic1"
    system: sega-saturn
    required: false
    size: 2097152  # 2 MB
    md5: "1cd19988d1d72a3e7caa0b73234c96b4"
    note: "Ultraman expansion ROM cart. Loaded when cart type set to Ultraman."
    source_ref: "mednafen/ss/cart.cpp:157-172, mednafen/settings.cpp:66-67"

  # -------------------------------------------------------
  # Action Replay 4M Plus (unfinished)
  # -------------------------------------------------------
  - name: "satar4mp.bin"
    system: sega-saturn
    required: false
    note: "Action Replay 4M Plus firmware. Unfinished in source, needs CPU UBC emulation."
    source_ref: "mednafen/ss/cart.cpp:174-188, mednafen/settings.cpp:68-69"

platform_details:
  saturn:
    bios_size: 524288         # 512 KB
    rom_cart_size: 2097152    # 2 MB max (rom.cpp)
    workram_low: 1048576      # 1 MB
    workram_high: 1048576     # 1 MB
    bios_address: "0x00000000-0x000FFFFF"
    cart_address: "0x02000000-0x03FFFFFF"
    hle_available: false
    source_ref: "mednafen/ss/ss.cpp:906-908"