Fujitsu - FM Towns (Geartowns)

Background

Geartowns is an open source, cross-platform Fujitsu FM Towns emulator written in C++.

• FM Towns Model ½, 1F/2F, 10F/20F, FM Towns II CX, UX, UG, HG, HR, UR, ME and MF/Fresh, and FM Towns Marty emulation with configurable CPU speed and RAM.
• 80386 dynamic recompiler (dynarec) on supported platforms.
• CD-ROM drive emulation with cue/bin, iso and chd images, m3u disc playlists and disc swapping.
• Physical CD-ROM disc support through the frontend.
• Two floppy drives with d77, d88, hdm, xdf, img, HxC mfm and raw bin images, also inside zip archives, m3u playlists, blank save disks and persistent disk changes.
• SCSI hard disks on IDs 0-6 with raw hdd, h0-h6 and hdm images and MAME hard disk CHDs, alone or in m3u playlists, with their changes kept in working copies.
• An IC memory card per content or shared by all content, kept in the save directory.
• Battery-backed CMOS shared by all content, or saved per game.
• Controllers:
  • Original FM Towns gamepad (2 buttons)
  • FM Towns Marty gamepad (2 buttons and Zoom)
  • 6 button gamepad
  • FM Towns mouse, also from an analog stick
• FM Towns keyboard support.
• Supported platforms (libretro): Windows, Linux, macOS, Android, iOS, tvOS and Raspberry Pi.

The Geartowns core has been authored by:

• Nacho Sanchez (drhelius)

The Geartowns core is licensed under:

• GPLv3

A summary of the licenses behind RetroArch and its cores can be found here.

BIOS

Geartowns requires the FM Towns system ROMs to work. Content does not load if a required ROM is missing, and the message lists the missing files.

Place the ROMs in a geartowns folder inside the frontend's system directory, in a subfolder of it such as geartowns/fmtowns/, or as the MAME set geartowns/fmtowns.zip. The system directory itself is searched the same way when the geartowns folder has no set for the machine.

Attention

FMT_SYS.ROM, FMT_DOS.ROM, FMT_FNT.ROM and FMT_DIC.ROM are required for Geartowns to function.

Filename	Description	Size	md5sum
FMT_SYS.ROM	System ROM - Required	256 KB	feaf8c5675151e00cfe3ad27673bff29
FMT_DOS.ROM	OS ROM - Required	512 KB	0585b19930d4a7f4c71bcc8a33746588
FMT_FNT.ROM	Font ROM - Required	256 KB	eb44f2093f51eb7159f03e170b13af76
FMT_DIC.ROM	Dictionary ROM - Required	512 KB	34847786d7de94b5d1133c956ab1d75d
FMT_F20.ROM	20-dot Font ROM - Optional	512 KB

The checksums above identify the FM Towns Model ½ ROMs, the recommended set. File names are accepted in any case (fmt_sys.rom, fmt_dos.rom, fmt_fnt.rom, fmt_dic.rom and fmt_f20.rom).

The FM Towns II UX needs its own set, MAME's fmtownsux, in geartowns/fmtownsux/ or as geartowns/fmtownsux.zip. The 1F/2F, 10F/20F, CX and UG have no dump of their own and run on this set:

Filename	Description	Size	md5sum
fmt_sys_a.rom	System ROM - Required	256 KB	90b5e01d42aaa93e8f4503a5e94e120b
fmt_dos_a.rom	OS ROM - Required	512 KB	03c8fac9a5f5f5f35fb5de5a5d0d018f
fmt_fnt.rom	Font ROM - Required	256 KB	b91300e55b70227ce98b59c5f02fa8dd
fmt_dic.rom	Dictionary ROM - Required	512 KB	8fa4e553f28cfc0c30a0a1e589799942
mytownsux.rom	Serial ROM - Optional	32 bytes	1a15f6c1b58ec7e5f850118610a787a7

The FM Towns II HR needs its own set, MAME's fmtownshr, in geartowns/fmtownshr/ or as geartowns/fmtownshr.zip. The FM Towns II HG and UR, from the same generation, have no dump of their own and run on it too:

Filename	Description	Size	md5sum
fmthr_sys.rom	System ROM - Required	256 KB	ecc8c37735e591a878d750d5976d7f52
fmt_dos.rom	OS ROM - Required	512 KB	0585b19930d4a7f4c71bcc8a33746588
fmt_fnt.rom	Font ROM - Required	256 KB	b91300e55b70227ce98b59c5f02fa8dd
fmt_dic.rom	Dictionary ROM - Required	512 KB	8fa4e553f28cfc0c30a0a1e589799942
mytownshr.rom	Serial ROM - Optional	32 bytes	72a96dabf0f9e5fe0bb47b08fa456815

The FM Towns II MF/Fresh needs the V10 set, MAME's FM Towns II Fresh TV set fmtownsftv, in geartowns/fmtownsftv/ or as geartowns/fmtownsftv.zip. The ME, which has no dump of its own, runs on it too, and so do the HG and UR without the HR set:

Filename	Description	Size	md5sum
fmt_sys.rom	System ROM - Required	256 KB	86fb6f7280689259f0ca839dd3dd6cde
fmt_dos.rom	OS ROM - Required	512 KB	0585b19930d4a7f4c71bcc8a33746588
fmt_fnt.rom	Font ROM - Required	256 KB	b91300e55b70227ce98b59c5f02fa8dd
fmt_dic.rom	Dictionary ROM - Required	512 KB	8fa4e553f28cfc0c30a0a1e589799942
fmt_f20.rom	20-dot Font ROM - Optional	512 KB	ac0c7021e9bf48ca84b51ab651169a88
mytownsftv.rom	Serial ROM - Optional	32 bytes

MAME's FM Towns II MX set fmtownsmx, in geartowns/fmtownsmx/ or as geartowns/fmtownsmx.zip, holds the same V10 ROMs in one file and is used the same way:

Filename	Description	Size	md5sum
fmtownsiimxbios.m79	OS, font, system, 20-dot font and dictionary ROMs - Required	2 MB	2f7d2e474054889bd1e7524f06dd0467
mytownsmx.rom	Serial ROM - Optional	32 bytes	b49dbab8ab2bfa387bf81ad519ea0cdf

The FM Towns Marty needs its own set: MAME's fmtmarty (mrom.m36 and mrom.m37, 2 MB each) in geartowns/fmtmarty/ or as geartowns/fmtmarty.zip, or the Marty 2 files (fmt_sys.rom, fmt_dos.rom, fmt_fnt.rom, fmt_dic.rom and mar_ex0.rom-mar_ex3.rom, the 2 MB extension ROM).

Each set is recognized by its system ROM. Modified or unknown ROMs and sets dumped from other FM Towns models also load, but the core shows a warning. The Free FM Towns Project replacement ROMs are recognized. A blank ROM is used if FMT_F20.ROM is not found, and a serial ROM is generated if MYTOWNS.ROM, mytownsux.rom, mytownshr.rom or mytownsftv.rom is not found.

Extensions

Content that can be loaded by the Geartowns core have the following file extensions:

• .cue
• .chd
• .iso
• .zip
• .d77
• .d88
• .hdm
• .xdf
• .img
• .mfm
• .bin
• .m3u
• .hdd
• .h0, .h1, .h2, .h3, .h4, .h5, .h6

Geartowns supports chd, iso and cue/bin CD-ROM images. Load the cue file, not a bin track. CUE audio tracks can use raw BIN, WAV (44.1 kHz, 16-bit stereo) or Ogg Vorbis files. Physical CD-ROM discs can be loaded with the frontend's Load Disc option where supported.

Floppy disk images can be d77, d88, hdm, xdf or img files, HxC mfm bitstream images such as MAME's copy-protected originals, or bin files holding a raw floppy image, also inside zip archives. Raw images may carry an E5 filler tail, and a 2HD image cut short at a track boundary loads with the missing tracks blank. Changes to an mfm disk are kept in a d77 working copy. A zip archive with several floppy images, such as MAME's multi-disk sets, lists each one as a separate disk control entry in file name order, like an m3u playlist, and starts from the first disk with an FM Towns boot sector. Zipped CD-ROM images are not supported; use chd or cue/bin. Multi-disk d77/d88 images expose each disk as a separate disk control entry.

Hard disk images are raw 512-byte sectors, the format other FM Towns emulators share. An h0 to h6 image goes to that SCSI ID; an hdd image, and an hdm image over 8 MB, to the first free one. An hdm image of 8 MB or less is a floppy disk. MAME hard disk CHDs load too, to the first free ID; a chd without hard disk geometry is a CD-ROM.

Features

Frontend-level settings or features that the Geartowns core respects.

Feature	Supported
Restart	✔
Screenshots	✔
Saves	✔ (CMOS, floppy, hard disks and IC memory card)
States	✔
Rewind	✔
Run-Ahead	✔
Netplay	✔ (gamepads and mouse)
Core Options	✔
Memory Monitoring (achievements)	✔
RetroArch Cheats	✔
Native Cheats	✕
Controls	✔
Remapping	✔
Multi-Mouse	✕
Rumble	✕
Sensors	✕
Camera	✕
Location	✕
Subsystem	✕
Softpatching	✕
Disk Control	✔
Username	✕
Language	✕
Crop Overscan	✕
LEDs	✕

Keyboard input is not synchronized in netplay. Netplay peers must start with the same floppy disk working copies. With the shared CMOS they must also start with the same CMOS file; set CMOS to Per Game for netplay.

Save states

States keep the machine and the identity of the inserted disks, but not the contents of the floppy disks. Loading a state or rewinding does not undo what a game wrote to a floppy disk. When a state was made with another disk in a drive, or with a disk in a drive that is now empty, the core inserts that disk from the disk control list and loads the state; if the disk is not in the list, the state does not load and the drives stay as they were. A drive that was empty when the state was made is emptied. States are about 3 MB with the default 2 MB of RAM and grow with the Main RAM option.

Hard disks work differently: loading a state, rewinding or run-ahead takes back what was written to a hard disk since that point, as long as the writes are among the last 32 MB per disk. When they aren't, or the state was made in another session, the state loads and a message says the hard disk changed since.

States saved by the Geartowns desktop application can't be loaded by the core.

Starting without content

The core can start without content. The BIOS waits for a boot disk; add a CD-ROM or floppy image with Disc Control > Append Disc and insert it.

Disk control

Disk controls manage both the CD-ROM drive and the floppy drives. Eject the current disk, select another disk index, then insert it again. A CD-ROM entry goes to the CD-ROM drive and a floppy entry goes to the floppy drive chosen with Disk Control Floppy Drive. The same floppy disk cannot be in both drives.

Each drive keeps its own disk. When the selected entry belongs to another drive, the ejected drive gets its disk back right away, so a CD-ROM game keeps its disc while a floppy disk is changed.

When content is opened again, the disk RetroArch remembers is used for CD-ROM entries. Floppy disk content always starts from its first disk.

Load an m3u playlist to add several CD-ROM or floppy images to the disk control list. Playlists can mix CD-ROM and floppy images; when they do, the first image of the other media type is also inserted at startup. Hard disk lines attach the disk to a SCSI ID instead; hard disks aren't in the disk control list and can't be swapped. Enable Floppy MultiDrive to also insert the floppy disk that follows the boot floppy into drive 2, wrapping to the start of the list.

Custom labels for the disk control list can be set with DISK_FILE|DISK_LABEL. On a zip with several floppy images, each entry shows the label followed by the image name. A blank label (DISK_FILE|) shows only the disk index. A #SAVEDISK:DiskName line adds a formatted blank 2HD save disk; DiskName is optional and is stored as the D77 disk name, not as a volume label on the disk. Save disks are created in the frontend's save directory as [M3U_FILE_NAME].save[N].d77 and labelled Save Disk N, counting from 0.

Game.m3u

Game (Disk 1).d77|Program Disk
Game (Disk 2).d77|Data Disk
#SAVEDISK:USER

Floppy disks

Geartowns never writes to the original floppy images. When a game writes to a floppy disk, the changes are stored as a working copy in the frontend's save directory and loaded automatically the next time the same disk is inserted. Changes are written a few seconds after the game stops writing, when the disk is ejected or swapped, and when the content is closed.

Delete the working copy to return to the original disk image.

Some software asks for a blank user or save disk. Enable Save Disk to add a formatted blank 2HD disk named "Save Disk" to the disk control list, or add a #SAVEDISK: line to an m3u playlist. Save disks are created in the save directory, and games write to them directly.

Hard disks

Load a hard disk image as content to boot from it, or list it in an m3u playlist with the CD-ROM a game installs from or runs with. A bootable CD boots before the disk; set Boot Device to the disk's SCSI ID to boot it with the CD in the drive. The 1F/2F and later models have a SCSI interface built in; the Model ½ gets its SCSI card while a hard disk is loaded, and the Marty has none. With only a hard disk, Model on Auto picks the Model ½, and Main RAM on Auto gives at least 4 MB while a hard disk is loaded, which Towns OS V2.1 needs to start from one. A CD-ROM game the database knows keeps its own RAM instead, unless Boot Device is a hard disk or the game runs from one.

Geartowns never writes to the original hard disk image. The first time the machine writes to it, the image is copied to the save directory as <image name>.save.<extension> (.save.hdd, raw, for a CHD), and from then on that working copy is used and updated. Changes are written a few seconds after the machine stops writing and when the content is closed. Delete the working copy to return to the original image. The first write to a large image copies all of it, which takes a moment. Two hard disk images with the same name can't be loaded together, and a working copy whose size doesn't match its image is not used; the content doesn't load until it is renamed or deleted.

Towns OS keeps its hard disk drive setup in the CMOS, not on the disk, and only uses the partitions that have a drive letter there. With Assign Drive Letters enabled, the default, every power-on and restart gives the partitions of each loaded hard disk that have none the free drive letters from D:, so a disk installed on another model or emulator boots; letters already set are kept. Disabled, such a disk stops with a message that the boot drive is not registered until it is added: boot the Towns OS V2.1 CD with the disk loaded, open Drive Configuration in TownsMENU's Settings menu, click the disk's SCSI ID, choose Add Drive and Execute, then restart without the CD.

IC memory card

Every model has a slot for a battery-backed SRAM card, which Towns OS uses as a drive. Set IC Memory Card to Per Game for a card named after the content, <content name>.icm, or to Shared for one card, geartowns.icm, for all content. Both are kept in the save directory. A missing card is created blank with IC Memory Card Size; an existing card keeps its size. Card images are raw, a whole number of KB up to 64 MB. Changes are written a few seconds after the machine stops writing and when the content is closed.

To use the card in Towns OS V2.1, add DEVICE=\SYS\TICM.SYS /U0 to CONFIG.SYS; the driver shows the card's drive letter at boot. Format the card with TICMFMT E: /S1024, the size in KB. That driver uses at most 8 MB of a card, and on the UX and the Marty cards larger than 2 MB lose data in transfers that cross from their second 1 MB bank into the third.

A card that starts with an IPL4 boot sector boots before the CD-ROM on every model. Save states don't hold the card: loading one, rewinding or run-ahead takes back what was written to the card since that point, and a message says when it can't.

CMOS

The FM Towns keeps its settings in 8 KB of battery-backed CMOS: the boot device, Towns OS settings and the OAK/2 kana-kanji user dictionary. By default the core keeps one CMOS for all content in the save directory, as on the real machine, so settings made by one program are seen by the others. The CMOS is saved a few seconds after it changes, on restart and when the content is closed. Set CMOS to Per Game to keep a separate CMOS in each content's .srm save file instead.

A new CMOS starts with the stock OAK/2 user dictionary that Towns OS boot disks install. Some games, such as Kyuukyoku Tiger, need it and stop at the Towns OS logo without it. On models with two floppy drives it also starts with Towns OS single-drive mode off, so floppy games such as Rance 2 find their second disk in drive B; a shared CMOS file from an older core version is updated once to match. Delete the CMOS file to start again with a new CMOS.

Save states include the CMOS. Loading a state also brings back the CMOS it was made with, and with the shared CMOS that is saved to the shared file.

Directories

The Geartowns core's library name is 'Geartowns'.

The Geartowns core saves/loads to/from these directories.

Frontend's System directory

File	Description
geartowns/FMT_SYS.ROM	System ROM
geartowns/FMT_DOS.ROM	OS ROM
geartowns/FMT_FNT.ROM	Font ROM
geartowns/FMT_DIC.ROM	Dictionary ROM
geartowns/FMT_F20.ROM	20-dot Font ROM

Subfolders and MAME zips there are searched too, and the system directory itself when the geartowns folder has no set for the machine.

Frontend's Save directory

File	Description
<model>.geartowns.cmos	Shared CMOS, one per model (model1_2, 1f_2f, 10f_20f, cx, ux, ug, hg, hr, marty)
*.srm	Per game CMOS
<image name>.<CRC32>.geartowns.d77	Floppy disk working copy
<image name>.<CRC32>.<N>.geartowns.d77	Working copy of disk N when an earlier disk of the same image is identical
<zip name>.<CRC32>.<M>.<N>.geartowns.d77	Working copy of disk N of zip member M when an earlier member holds the same disk
<content name>.save.d77	Save disk
<m3u name>.save<N>.d77	Playlist save disk
<image name>.save.<extension>	Hard disk working copy
<content name>.icm	Per game IC memory card
geartowns.icm	Shared IC memory card

Frontend's State directory

File	Description
*.state#	State

Geometry and timing

• The Geartowns core reports a dynamic refresh rate that follows the vertical sync rate of the emulated CRTC
• The Geartowns core's provided sample rate is 44100 Hz
• The Geartowns core's base size follows the active video mode, starting at 640x480
• The Geartowns core's max width is 1024
• The Geartowns core's max height is 768
• The Geartowns core's default aspect ratio is 4:3; the 'Aspect Ratio' core option can change it

Core options

The Geartowns core has the following options that can be tweaked from the core options menu. The default setting is bolded.

Settings marked (restart) take effect after reloading the content.

• Aspect Ratio [geartowns_aspect_ratio] (1:1 PAR|4:3 DAR|16:9 DAR|16:10 DAR)

  Select which aspect ratio will be presented by the core. 1:1 PAR produces square pixels at monitor resolution, also when Native Resolution outputs fewer pixels.

• Native Resolution [geartowns_native_resolution] (Enabled|Disabled)

  Output one pixel per game pixel, as shaders expect. When disabled, zoomed modes are output at monitor resolution.

• Frameskip [geartowns_frameskip] (Disabled|Auto|Manual)

  Skip frames to avoid audio crackling when the device is too slow. Auto skips when the frontend reports that the audio buffer is about to run out, Manual uses Frameskip Threshold (%).

• Frameskip Threshold (%) [geartowns_frameskip_threshold] (33|15-60)

  With Manual frameskip, skip frames while the audio buffer is below this percentage. Higher values reduce crackling but skip more frames. Shown when Frameskip is Manual.

• FM Volume [geartowns_fm_volume] (100|0-200)

  Volume of the FM synthesizer, as a percentage.

• PCM Volume [geartowns_pcm_volume] (100|0-200)

  Volume of the PCM sound source, as a percentage.

• CD-DA Volume [geartowns_cdda_volume] (100|0-200)

  Volume of the CD-ROM audio tracks, as a percentage.

• Buzzer Volume [geartowns_buzzer_volume] (100|0-200)

  Volume of the buzzer that plays system beeps, as a percentage.

• 16-bit PCM Volume [geartowns_pcm16_volume] (100|0-200)

  Volume of the 16-bit PCM of the FM Towns II ME and MF/Fresh, as a percentage.

• Allow Opposing Directions [geartowns_up_down_allowed] (Disabled|Enabled)

  Enable this option to press, quickly alternate, or hold both left and right, or up and down, at the same time.

  This may cause movement-based glitches in some software.

  It is best to keep this option disabled.

• Mouse Sensitivity [geartowns_mouse_sensitivity] (5|1-15)

  Adjust FM Towns mouse sensitivity. Higher values move the cursor faster.

• Analog Stick Mouse [geartowns_analog_mouse] (Disabled|Left stick|Right stick)

  Move the FM Towns mouse with an analog stick of the first controller. L2 and R2 are the mouse buttons. Needs a mouse port, port 2 by default.

• Analog Mouse Speed [geartowns_analog_mouse_speed] (5|1-10)

  Adjust how fast the analog stick moves the FM Towns mouse. Shown when Analog Stick Mouse is enabled.

• Preload CD-ROM (restart) [geartowns_cdrom_preload] (Disabled|Enabled)

  Preload all CD-ROM tracks into RAM. This increases memory usage but may improve performance.

• CD-ROM Read Speed [geartowns_cdrom_speed] (Auto|1x|2x|4x|8x)

  How fast the drive reads sectors. Auto reads at the speed of the model's drive: 2x on the FM Towns II ME and MF/Fresh in high-speed mode, 1x on the rest. Faster speeds reduce loading times, but some software may not expect a faster drive.

• Disk Control Floppy Drive [geartowns_floppy_drive] (Floppy 1|Floppy 2)

  Select the floppy drive that the frontend's disk control ejects and inserts floppy disks into.

• Floppy MultiDrive (restart) [geartowns_floppy_multidrive] (Disabled|Enabled)

  Also insert the floppy that follows the boot floppy into drive 2, for software that reads from both drives.

• Save Disk (restart) [geartowns_save_disk] (Disabled|Enabled)

  Add a blank 2HD floppy disk to the disk control list for software that asks for a user or save disk. It is stored in the save directory.

• Model (restart) [geartowns_model] (Auto|FM Towns (Model ½) (80386DX 16 MHz)|FM Towns 1F/2F (80386DX 16 MHz)|FM Towns 10F/20F (80386DX 16 MHz)|FM Towns II CX (80386DX 16 MHz)|FM Towns II UX (80386SX 16 MHz)|FM Towns II UG (80386SX 20 MHz)|FM Towns II HG (80386DX 20 MHz)|FM Towns II HR (80486SX 20 MHz)|FM Towns II UR (80486SX 20 MHz)|FM Towns II ME (80486SX 25 MHz)|FM Towns II MF / Fresh (80486SX 33 MHz)|FM Towns Marty (80386SX 16 MHz))

  The FM Towns model to emulate. Auto picks the machine, CPU speed and RAM the game database names for the game, the FM Towns II HG for 1.44 MB floppy disks, and the FM Towns (Model ½) for other content. It is recommended to leave this option on Auto. RetroArch's 'Save Game Options' keeps a choice for one game.

• CPU Speed (restart) [geartowns_cpu_clock] (Auto|16 MHz|20 MHz|25 MHz|33 MHz|40 MHz|50 MHz|66 MHz|100 MHz)

  Auto runs the CPU at the model's original clock, or at the speed the game database names when Model is on Auto. Devices keep their real timing at any speed. Some software may not expect a faster CPU.

• Main RAM (restart) [geartowns_main_ram] (Auto|1 MB|2 MB|4 MB|6 MB|8 MB|10 MB|12 MB|16 MB|20 MB|24 MB|26 MB|28 MB|32 MB|48 MB|64 MB|68 MB)

  Auto uses the model's original RAM, or the RAM the game database names when Model is on Auto. A size the model doesn't offer uses its next size up, or its largest. Some software needs more than 2 MB. Save states grow with it. The RAM size only changes when the content is loaded again; a restart keeps the running size, so achievement and cheat addresses stay valid.

• FPU (restart) [geartowns_fpu] (Auto|None|80387 or 487SX)

  The math coprocessor: an 80387 card on the 386 models, a 487SX card on the HR, ME and MF/Fresh. Auto fits one when the game database names one for the game and Model is on Auto, otherwise it keeps the model's original, none on every emulated model. The UX, UG, UR and Marty have no socket for it. A few games need one, and some run different code with one fitted.

• Speed Mode (restart) [geartowns_speed_mode] (Auto|Compatible|High Speed)

  The FM Towns II models, except the UX, run in compatible or high-speed mode. High speed cuts memory waits and turns on the 486 cache and the 2x CD-ROM where fitted. The system ROM sets the mode at reset from the CMOS, where TownsMENU saves it. Auto uses high speed when Model is on Auto and the game database picks a 486 model, otherwise it keeps the CMOS setting, compatible on a new CMOS. Some software misbehaves in high-speed mode.

• Boot Device (restart) [geartowns_boot_device] (Auto|CD-ROM|Floppy 1|Floppy 2|Hard Disk ID 0|Hard Disk ID 1|Hard Disk ID 2|Hard Disk ID 3|Hard Disk ID 4|IC Memory Card)

  Holds the system ROM's boot keys at power-on and on every restart: C+D for the CD-ROM, F+0 or F+1 for a floppy drive, H+0 to H+4 for a SCSI hard disk, I+C+M for the IC memory card, released at the first read from a disk. The 1F/2F and later models read them; the Model ½ and Marty ROMs don't. Auto boots as usual, the CD first, so a hard disk boots with a bootable CD in the drive only when it is chosen here. A memory card that starts with a boot sector boots ahead of the CD on every model.

• Assign Drive Letters (restart) [geartowns_drive_letters] (Enabled|Disabled)

  Towns OS keeps hard disk drive letters in the CMOS, not on the disk. When enabled, each restart gives free letters to the partitions the CMOS doesn't list yet, so disks set up elsewhere boot. When disabled, register them yourself in Towns OS.

• IC Memory Card (restart) [geartowns_memory_card] (Off|Per Game|Shared)

  Puts an IC memory card in the slot, kept in the save directory. 'Per Game' uses a card named after the content, 'Shared' one card for all content. A missing card is created blank with the size below; Towns OS formats it with TICMFMT once CONFIG.SYS loads TICM.SYS.

• IC Memory Card Size (restart) [geartowns_memory_card_size] (64 KB|128 KB|256 KB|512 KB|1 MB|2 MB|4 MB|8 MB|16 MB|32 MB|64 MB)

  Size of a new blank IC memory card. An existing card keeps its size. The UG reaches the first 1 MB of a card, the Model ½, 1F/2F and 10F/20F the first 16 MB.

• Clock Start (restart) [geartowns_rtc] (Host time|Fixed date)

  Start the FM Towns clock from the host time or from a fixed date (January 1, 1990). A fixed date makes netplay and replays independent of each computer's clock.

• CMOS (restart) [geartowns_cmos] (Shared|Per Game)

  Where the battery-backed CMOS with the machine settings and the OAK/2 user dictionary is kept. 'Shared' keeps one CMOS for all content in the save directory, like the real machine. 'Per Game' keeps a separate CMOS in each content's save file, a better choice for netplay.

• CPU Dynarec [geartowns_dynarec] (Enabled|Disabled)

  Use dynamic recompilation. Most games will run faster but some games may run slower.

  The core falls back to the interpreter if the frontend can't run generated code. This option is not available on iOS and tvOS.

Joypad

Port 1 defaults to Original gamepad and port 2 to Mouse. Both ports also accept Marty gamepad, 6 button gamepad and Keyboard, port 1 accepts Mouse and port 2 Original gamepad. For a second gamepad, set port 2 to a gamepad type.

RetroPad Inputs	Original gamepad	Marty gamepad	6 button gamepad
	D-Pad Up	D-Pad Up	D-Pad Up
	D-Pad Down	D-Pad Down	D-Pad Down
	D-Pad Left	D-Pad Left	D-Pad Left
	D-Pad Right	D-Pad Right	D-Pad Right
	Select	Select	Select
	Run	Run	Run
	A	A	C
	B	B	B
			A
			Y
			X
		Zoom	Z

A port set to Keyboard has no FM Towns gamepad. Use RetroArch's keyboard mapping in Quick Menu > Controls to assign FM Towns keys to the RetroPad buttons of that port.

Mouse

The mouse is in port 2 by default. Set port 1 to Mouse to move it there; port 2 left at Mouse then works as an Original gamepad, since only one mouse is supported. The FM Towns mouse follows the mouse of RetroArch's first user, whichever port it is plugged into. Adjust movement with Mouse Sensitivity.

RetroMouse Inputs	FM Towns Mouse
Mouse movement	Movement
Left button	Left button
Right button	Right button

Without a mouse, enable Analog Stick Mouse to move the FM Towns mouse with an analog stick of the first controller.

RetroPad Inputs	FM Towns Mouse
Left or right analog stick	Movement
	Left button
	Right button

Keyboard

The host keyboard is mapped to the FM Towns keyboard by key position. Letters, numbers, cursor keys, the numeric keypad, Shift, Left Ctrl, Alt, Tab, Space, Enter, Backspace, Insert, Delete and Home map to the FM Towns keys with the same names.

Attention

Outside Game Focus mode, RetroArch does not pass keys bound to hotkeys or to RetroPad buttons to the core. With the default bindings this includes F1-F9, F11, Enter, Space, Escape, the cursor keys and many letters. Enable Game Focus (Scroll Lock by default) before typing, or set Settings > Input > Auto Game Focus to Detect. On keyboards without Scroll Lock, bind Game Focus to another key in Settings > Input > Hotkeys.

Keys that map to a different FM Towns key:

Host key	FM Towns key
F1 - F15	PF1 - PF15
Escape / Pause	BREAK
` (backquote)	ESC
= (equals)	^
[ (left bracket)	@
] (right bracket)	[
\ (backslash)	¥
# (UK keyboards)	]
' (quote)	:
Caps Lock	CAPS
Page Up	PREVIOUS
Page Down	NEXT
Print Screen	COPY
Right Alt	Kana/Kanji
Right Ctrl	KATAKANA
Left Super	NO CONVERT
Right Super	CONVERT
Menu	HIRAGANA

The FM Towns HALF/FULL, PF16-PF20, keypad 000 and dictionary keys have no host key in the libretro core. On keyboards without a # key, map # to a button with RetroArch's keyboard mapping to reach the FM Towns ] key.

External Links

• Official Geartowns Github Repository
• Libretro Geartowns Core info file
• Report Libretro Geartowns Core Issues Here