Skip to content

Geartowns
Type libretro
Classification Official ports
Source https://github.com/drhelius/Geartowns
Version 0.0.6-8-g25d2025
Revision drhelius/Geartowns@25d2025be28e
Profiled 2026-10-17
Profile YAML, JSON
Cores geartowns
Systems fmtowns
Technical 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, 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:497-508): 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: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), 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:2753-2767). It is state, not a file to obtain.

5 files | 1 required, 4 optional | 5 in repo, 0 missing Categories: 5 BIOS ZIPs

fmtowns.zip required in repo bios_zip #
FM Towns Model 1/2 firmware set

fmtownsux.zip optional in repo bios_zip #
FM Towns II UX firmware set

fmtmarty.zip optional in repo bios_zip #
FM Towns Marty firmware set

fmtownshr.zip optional in repo bios_zip #
FM Towns II HR firmware set

fmtownsftv.zip optional in repo bios_zip #
FM Towns II Fresh TV firmware set

Generated on 2026-10-20T03:49:41Z