libretro/emulators/geartowns.yml

emulator: "Geartowns"
type: libretro
core_classification: official_port
source: "https://github.com/drhelius/Geartowns"
upstream: "https://github.com/drhelius/Geartowns"
profiled_date: "2026-10-27"
source_commit: "996d42b098bd572ba66a8246bfe56cee39e5ff6e"
core_version: "1.0.1"
display_name: "Fujitsu - FM Towns (Geartowns)"
cores:
  - "geartowns"
systems:
  - "fmtowns"

notes: |
  FM Towns emulator by Ignacio Sanchez (drhelius). The same tree builds the
  desktop application and the libretro core (platforms/libretro). The core
  emulates the Model 1/2, 1F/2F, 10F/20F, II CX, UX, UG, HG, HR and the Marty
  (src/system/machine_profiles.h:112-126, `emulated` field). The version string
  is `git describe` at build time (platforms/libretro/Makefile:369-371).

  retro_load_game() fails when load_bios() finds no firmware
  (platforms/libretro/libretro.cpp:738-742). load_bios() searches
  system/geartowns first, then the system directory itself, each time
  accepting first only a set made for the selected model and then any set
  (platforms/libretro/libretro.cpp:844-871). Firmware::FindSources() takes
  as candidates the folder itself, every direct subfolder and every .zip in
  it (src/media/firmware.cpp:288-348). Folder and zip names are free. A
  candidate counts only when the System, OS, Font and Dictionary ROMs are all
  present at the right size, and the CRC32 of its System ROM names the set
  (src/media/firmware.cpp:377-416, src/media/firmware.h:115-124).

  Six sets are known (src/media/firmware.h:115-124): fmtowns (Model 1/2),
  freetowns (Free FM Towns Project replacement ROMs, used by the Model 1/2),
  fmtownsux (UX, also used by 1F/2F, 10F/20F, CX and UG), fmtmarty (Marty),
  fmtownshr (HR, also used by the HG) and fmtownsftv (also used by the HG,
  after fmtownshr). On Auto the
  model comes from the game database and falls back to the Model 1/2 or to
  the first model in release order that has a set
  (src/geartowns_core.cpp:1986-2022, src/geartowns_core.cpp:2106-2111). A
  1.44 MB floppy (2HD at 300 rpm) inserted on Auto replaces a model without a
  three-mode drive by the first one in release order that has it, the HG
  (src/geartowns_core.cpp:776-779, src/geartowns_core.cpp:1997-2005), which
  uses the fmtownshr or fmtownsftv set. A set made for another model still
  loads in the second pass, with a warning
  (platforms/libretro/libretro.cpp:873-906).

  File names are matched without case, inside a zip only at the archive root
  (src/media/firmware.cpp:617-666). Accepted names, one group per component,
  are (FMT_SYS.ROM, FMT_SYS_A.ROM, FMTHR_SYS.ROM), (FMT_DOS.ROM, FMT_DOS_A.ROM),
  (FMT_FNT.ROM), (FMT_DIC.ROM), (FMT_F20.ROM, FMT_F20_A.ROM), (MYTOWNS.ROM,
  MYTOWNSUX.ROM, MYTOWNSM2.ROM, MYTOWNSFTV.ROM, MYTOWNSHR.ROM) and (MAR_EX0.ROM
  to MAR_EX3.ROM) (src/media/firmware.cpp:28-42). Without separate files the
  Marty components are cut from MROM.M36 and MROM.M37, 2 MiB each
  (src/media/firmware.cpp:500-511): OS at 0 and the first three extension
  parts in M36, and the fourth extension part, 20-dot font at 0x80000,
  dictionary at 0x100000, font at 0x180000 and System ROM at 0x1C0000 in M37.

  Each component must have its exact size or it is rejected
  (src/media/firmware.cpp:533-615, src/common/defines.h:48-55): System
  256 KiB, OS 512 KiB, Font 256 KiB, Dictionary 512 KiB, 20-dot Font 512 KiB,
  Serial 32 bytes, Extension 2 MiB (four 512 KiB parts). System, OS, Font and
  Dictionary are required. A missing 20-dot Font or Extension is replaced by
  0xFF, a missing Serial ROM is generated (src/media/firmware.cpp:76-165,
  src/media/firmware.cpp:260-263). The CRC32 of every component is looked up
  in game_db.h (src/media/firmware.cpp:167-184, src/media/game_db.h:344-376),
  and an unknown CRC only produces a warning. The Free FM Towns set is known by
  System 65DC3B1F, OS 43C18E92, Font 736D9CB1 and a blank Dictionary
  504BF849. The Marty slices are known by System 937311F6, OS 2BC2AF96,
  Extension E1A9FA72 and 20-dot Font 75660AAC.

  The CMOS is written by the core next to the saves
  (platforms/libretro/libretro.cpp:3019-3033). It is state, not a file to
  obtain.

files:
  - name: "fmtowns.zip"
    description: "FM Towns Model 1/2 firmware set"
    system: "fmtowns"
    category: bios_zip
    path: "geartowns/fmtowns.zip"
    required: true
    contents:
      - { name: "fmt_sys.rom", size: 262144, crc32: "53319e23" }
      - { name: "fmt_dos.rom", size: 524288, crc32: "112872ee" }
      - { name: "fmt_fnt.rom", size: 262144, crc32: "955c6b75" }
      - { name: "fmt_dic.rom", size: 524288, crc32: "b314c659" }
    source_ref: "platforms/libretro/libretro.cpp:738-742, platforms/libretro/libretro.cpp:853-871, src/media/firmware.h:117, src/media/firmware.cpp:28-33, src/media/firmware.cpp:288-348, src/media/game_db.h:344-348"
    note: >
      Set for the Model 1/2, the machine Auto falls back to. The same four
      files load from any subfolder of system/geartowns or from
      system/geartowns itself. The core has no CRC for a Model 1/2 20-dot
      Font, and fmt_f20.rom is read when present.

  - name: "fmtownsux.zip"
    description: "FM Towns II UX firmware set"
    system: "fmtowns"
    category: bios_zip
    path: "geartowns/fmtownsux.zip"
    required: false
    contents:
      - { name: "fmt_sys_a.rom", size: 262144, crc32: "92f3fa67" }
      - { name: "fmt_dos_a.rom", size: 524288, crc32: "22270e9f" }
      - { name: "fmt_fnt.rom", size: 262144, crc32: "dd6fd544" }
      - { name: "fmt_dic.rom", size: 524288, crc32: "82d1daa2" }
      - { name: "mytownsux.rom", size: 32, crc32: "5cc7e6bc" }
    source_ref: "src/media/firmware.h:119-120, src/media/firmware.cpp:28-34, src/media/game_db.h:350-355"
    note: "Set for the UX, also used by the 1F/2F, 10F/20F, CX and UG."

  - name: "fmtmarty.zip"
    description: "FM Towns Marty firmware set"
    system: "fmtowns"
    category: bios_zip
    path: "geartowns/fmtmarty.zip"
    required: false
    contents:
      - { name: "mrom.m36", size: 2097152 }
      - { name: "mrom.m37", size: 2097152 }
    source_ref: "src/media/firmware.h:121, src/media/firmware.cpp:500-511, src/media/game_db.h:357-361"
    note: >
      The core checks the CRC32 of the slices it cuts from the two mask
      ROMs, not of the files: System 937311F6, OS 2BC2AF96, Extension
      E1A9FA72, 20-dot Font 75660AAC. The Marty 2 layout with separate
      FMT_*.ROM and MAR_EX0.ROM to MAR_EX3.ROM files is read the same way.

  - name: "fmtownshr.zip"
    description: "FM Towns II HR firmware set"
    system: "fmtowns"
    category: bios_zip
    path: "geartowns/fmtownshr.zip"
    required: false
    contents:
      - { name: "fmthr_sys.rom", size: 262144, crc32: "8aeff982" }
      - { name: "fmt_dos.rom", size: 524288 }
      - { name: "fmt_fnt.rom", size: 262144 }
      - { name: "fmt_dic.rom", size: 524288 }
      - { name: "mytownshr.rom", size: 32, crc32: "c52f0e89" }
    source_ref: "src/media/firmware.h:122, src/media/firmware.cpp:28-34, src/media/game_db.h:363-365"
    note: "Set for the HR, and first choice for the HG."

  - name: "fmtownsftv.zip"
    description: "FM Towns II Fresh TV firmware set"
    system: "fmtowns"
    category: bios_zip
    path: "geartowns/fmtownsftv.zip"
    required: false
    contents:
      - { name: "fmt_sys.rom", size: 262144, crc32: "afe4ebcf" }
      - { name: "fmt_dos.rom", size: 524288 }
      - { name: "fmt_fnt.rom", size: 262144 }
      - { name: "fmt_dic.rom", size: 524288 }
      - { name: "fmt_f20.rom", size: 524288, crc32: "9f55a20c" }
      - { name: "mytownsftv.rom", size: 32, crc32: "a961aae7" }
    source_ref: "src/media/firmware.h:123, src/media/firmware.cpp:28-34, src/media/game_db.h:367-370"
    note: "Second choice for the HG. The MF/Fresh itself is not emulated."