emulator: "Geartowns" type: libretro core_classification: official_port source: "https://github.com/drhelius/Geartowns" upstream: "https://github.com/drhelius/Geartowns" profiled_date: "2026-10-17" source_commit: "25d2025be28e9fcc319f597a516f21e0778f770b" core_version: "0.0.6-8-g25d2025" 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 and the Marty (src/system/machine_profiles.h:61-75, `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:704-708). 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:798-825). Firmware::FindSources() takes as candidates the folder itself, every direct subfolder and every .zip in it (src/media/firmware.cpp:286-346); 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:375-414, src/media/firmware.h:114-123). Six sets are known (src/media/firmware.h:114-123): 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 and fmtownsftv (both used by the HG, HR preferred). 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:1624-1649, src/geartowns_core.cpp:1691-1696). A set made for another model still loads in the second pass, with a warning (platforms/libretro/libretro.cpp:827-860). File names are matched without case, inside a zip only at the archive root (src/media/firmware.cpp:614-663). Accepted names 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; 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:497-508): OS at 0 and the first three extension parts in M36; 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:530-612, src/common/defines.h:47-54): 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:73-163, src/media/firmware.cpp:258-261). The CRC32 of every component is looked up in game_db.h (src/media/firmware.cpp:165-182, src/media/game_db.h:303-335); 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:2753-2767); 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:704-708, platforms/libretro/libretro.cpp:807-825, src/media/firmware.h:116, src/media/firmware.cpp:28-33, src/media/firmware.cpp:286-346, src/media/game_db.h:303-307" 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; 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:118-119, src/media/firmware.cpp:28-34, src/media/game_db.h:309-314" 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:120, src/media/firmware.cpp:497-508, src/media/game_db.h:316-320" 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:121, src/media/firmware.cpp:28-34, src/media/game_db.h:322-324" note: "First choice for the HG; the HR itself is not emulated." - 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:122, src/media/firmware.cpp:28-34, src/media/game_db.h:326-329" note: "Second choice for the HG; the MF/Fresh itself is not emulated."