FCE Ultra General Documentation

Last updated May 16, 2004
Valid as of FCE Ultra 0.98.10

Table of Contents:


FCE Ultra is an NTSC and PAL Famicom/NES emulator for various platforms. It is based upon Bero's original FCE source code. Current features include good PPU, CPU, pAPU, expansion chip, and joystick emulation. Also a feature unique to this emulator(at the current time) is authentic Game Genie emulation. Save states and snapshot features also have been implemented.

This document has been arranged to keep user interface details and emulation details as separate as possible, though this has not been accomplished entirely.

In several places references are made to the "base directory". If you are running a port on a UN*X-like system(Linux/*BSD/Mac OSX/SunOS/etc.), the base directory is "~/.fceultra", or in other words, "your home directory plus .fceultra". For all other ports(including DOS and MS Windows), the base directory is the directory that the executable is in.

History of FCE Ultra

This section is a work-in-progress. Some details may be incorrect.
Bero originally wrote a NES emulator that was referred to as FCE. This name was apparently meant only to serve as a temporary name, but its usage remained. Xodnizel originally ported it to Linux SVGAlib, and made a few improvements. This code base was abandoned, and work began anew, under DOS, with the original FCE source code. At the end of November, 1998, FCE Ultra Beta 1 was released.

FCE Ultra remained DOS-only until version 0.18, when it was ported to Linux SVGAlib, and released as a staticly-linked executable. The first MS Windows port was released as version 0.25.

The source code of 0.40 was released on November 12, 2000. It retained the simple license of FCE for a long time, which stated that " This software is freeware.you can use it non-commercially." Almost two years later, in June 2002, 0.80 was released, and FCE Ultra was relicensed under the GNU GPL.

Core Features


All official instructions of the NES' CPU, the 2A03, which is compatible(mostly) with the 6502, are emulated. "Unofficial" instructions are also emulated, though probably not as accurately as the more well-defined official instructions.



FCE Ultra has many palette features, including loading a custom palette to replace the default NES palette. The palette from an NTSC NES can also be generated on-the-fly.

First, a note on on the format of external palettes; Palette files are expected to contain 64 8-bit RGB triplets(each in that order; red comes first in the triplet in the file, then green, then blue). Each 8-bit value represents brightness for that particular color. 0 is minimum, 255 is maximum.

Palettes can be set on a per-game basis. To do this, put a palette file in the "gameinfo" directory with the same base filename as the game you wish to associate with and add the extension "pal". Examples:

                File name:              Palette file name:
                 BigBad.nes              BigBad.pal
                 BigBad.zip              BigBad.pal
                 BigBad.Better.nes       BigBad.Better.pal

With so many ways to choose a palette, figuring out which one will be active may be difficult. Here's a list of what palettes will be used, in order from highest priority to least priority(if a condition doesn't exist for a higher priority palette, the emulator will continue down its list of palettes).


All 5 internal sound channels are supported(2x rectangle, triangle, noise, and DMC/PCM). Sound channels are emulated with CPU instruction granularity. There are two sound quality options. Low-quality sound, the default sound quality option, generates sound data at 16x the playback rate and averages those samples together to 1 sample. This method works fairly well and is reasonably fast, but there is still some aliasing and sound distortion. All sample rates between 8192Hz and 96000Hz are supported.

The high-quality sound emulation is much more CPU intensive, but the quality is worth it, if your machine is fast enough. Sound data is generated at the NES' CPU clock rate(about 1.8MHz for the NTSC NES), and then resampled to the output sample rate. Custom-designed 483rd order Parks-McClellan algorithm filter coefficients are used. Supported playback rates are 44100Hz, 48000Hz, and 96000Hz. The following filter statistics apply for NTSC emulation.

Rate:Passband Upper Bound(Hz):Passband ripple(dB):Transition bandwidth(Hz):Stopband attenuation(dB):

The "highest" sound quality mode is similar to the normal high-quality mode, but the filters are of a higher order(1024 coefficients). Ripple is reduced, the upper bound of the passband is higher, and the stopband attenuation is slightly higher. The highest-quality mode filter coefficients were created using "gmeteor". The parameters used to create these filters can be found in the source code distribution.

Besides the 5 internal NES sound channels, FCE Ultra emulates the extra sound capabilities of the Konami VRCVI, Konami VRCVII, Namco 106, Nintendo MMC5, and the Sunsoft FME-07 chips. The extra sound channel in the Famicom Disk System is also emulated, but the support for its FM capabilities is limited.


FCE Ultra emulates the standard NES gamepad, the Four-Score multiplayer adapter, the Zapper, the Power Pad, and the Arkanoid controller. The Famicom version of the Arkanoid controller, the "Space Shadow" gun, the Famicom 4-player adapter, the Family Keyboard, the HyperShot controller, the Mahjong controller, the Oeka Kids tablet, the Quiz King buzzers, the Family Trainer, and the Barcode World barcode reader are also emulated.


Most Zapper NES games expect the Zapper to be plugged into port 2. and most VS Unisystem games expect the Zapper to be plugged into port 1.

The left mouse button is the emulated trigger button for the Zapper. The right mouse button is also emulated as the trigger, but as long as you have the right mouse button held down, no color detection will take place, which is effectively like pulling the trigger while the Zapper is pointed away from the television screen. Note that you must hold the right button down for a short time to have the desired effect.

File Formats/Expansion Hardware

FCE Ultra supports the iNES, FDS(raw and with a header), UNIF, and NSF file formats. FDS ROM images in the iNES format are not supported; it would be silly to do so and storing them in that format is nonsensical.

FCE Ultra supports loading ROM/disk images from some types of compressed files. FCE Ultra can load data from both PKZIP-format files and gzip-format files. Only the "deflate" algorithm is supported, but this is the most widely used algorithm for these formats.

All files in a PKZIP format archive will be scanned for the followings extensions: .nes, .fds, .nsf, .unf, .nez, .unif The first archived file to have one of these extensions will be loaded. If no archived file has one of these extensions, the first archived file will be loaded.

iNES Format

The battery-backed RAM, vertical/horizontal mirroring, four-screen name table layout, and 8-bit mapper number capabilities of the iNES format are supported. The 512-byte trainer capability is also supported, but it is deprecated. Common header corruption conditions are cleaned(let's go on a DiskDude hunt), though not all conditions can be automatically detected and fixed. In addition, a few common header inaccuracies for games are also corrected(detected by CRC32 value). Note that these fixes are not written back to the storage medium.

Support for the recent VS System bit and "number of 8kB RAM banks" is not implemented. Too many iNES headers are corrupt where this new data is stored, causing problems for those games.

The following table lists iNES-format "mappers" supported well in FCE Ultra.

Number:Description:Game Examples:
0No bankswitchingDonkey Kong, Mario Bros
1Nintendo MMC1MegaMan 2, Final Fantasy
2Simple 16KB PROM Switch(UNROM)MegaMan, Archon, 1944
3Simple 8KB VROM Switch(CNROM)Spy Hunter, Gradius
4Nintendo MMC3Super Mario Bros. 3, Recca, Final Fantasy 3
5Nintendo MMC5Castlevania 3, Just Breed, Bandit Kings of Ancient China
6FFE F4 Series(hacked, bootleg)
7AOROMBattle Toads, Time Lord
8FFE F3 Series(hacked, bootleg)
9Nintendo MMC2Punchout!
10Nintendo MMC4Fire Emblem, Fire Emblem Gaiden
11Color DreamsCrystal Mines, Bible Adventures
12??Dragon Ball Z 5 ("bootleg" original)
15Multi-cart(bootleg)100-in-1: Contra Function 16
16Bandai ??Dragon Ball Z, SD Gundam Gaiden **EEPROM NOT SUPPORTED
17FFE F8 Series(hacked, bootleg)
18Jaleco SS806Pizza Pop, Plasma Ball
19Namco 106Splatter House, Mappy Kids
21Konami VRC4 2AWaiWai World 2, Ganbare Goemon Gaiden 2
22Konami VRC4 1BTwinbee 3
23Konami VRC2BWaiWai World, Crisis Force
24Konami VRC6Akumajou Densetsu
25Konami VRC4Gradius 2, Bio Miracle:Boku tte Upa
26Konami VRC6 A0-A1 SwapEsper Dream 2, Madara
32IREM G-101Image Fight 2, Perman
33Taito TC0190/TC0350Don Doko Don
34NINA-001 and BNROMImpossible Mission 2, Deadly Towers, Bug Honey
40(bootleg)Super Mario Bros. 2
41Caltron 6-in-1Caltron 6-in-1
42(bootleg)Mario Baby
44Multi-cart(bootleg)Super HiK 7 in 1
45Multi-cart(bootleg)Super 1000000 in 1
46Game StationRumble Station
47NES-QJNintendo World Cup/Super Spike V-Ball
48Taito TC190VFlintstones
49Multi-cart(bootleg)Super HiK 4 in 1
50(bootleg)Super Mario Bros. 2
51Multi-cart(bootleg)11 in 1 Ball Games
52Multi-cart(bootleg)Mario Party 7 in 1
57Multi-cart(bootleg)Game Star GK-54
58Multi-cart(bootleg)68-in-1 Game Star HKX5268
60Multi-cart(bootleg)4 in 1(Reset-selected)
61Multi-cart(bootleg)20 in 1
62Multi-cart(bootleg)Super 700 in 1
64Tengen RAMBO 1Klax, Rolling Thunder, Skull and Crossbones
65IREM H-3001Daiku no Gensan 2
66GNROMSMB/Duck Hunt
67Sunsoft ??Fantasy Zone 2
68Sunsoft ??After Burner 2, Nantetta Baseball
69Sunsoft FME-7Batman: Return of the Joker, Hebereke
70??Kamen Rider Club
71CamericaFire Hawk, Linus Spacehead
72Jaleco ??Pinball Quest
73Konami VRC3Salamander
74Taiwanese MMC3 CHR ROM w/ VRAMSuper Robot Wars 2
75Jaleco SS8805/Konami VRC1Tetsuwan Atom, King Kong 2
76Namco 109Megami Tensei
77IREM ??Napoleon Senki
78Irem 74HC161/32Holy Diver
79NINA-06/NINA-03F15 City War, Krazy Kreatures, Tiles of Fate
80Taito X-005Minelvation Saga
82Taito ??Kyuukyoku Harikiri Stadium - Heisei Gannen Ban
83Multi-cart(bootleg)Dragon Ball Party
85Konami VRC7Lagrange Point
86Jaleco JF-13More Pro Baseball
88Namco 118Dragon Spirit
89Sunsoft ??Mito Koumon
90??Super Mario World
91??Mari Street Fighter 3 Turbo
92Jaleco ??MOERO Pro Soccer
93??Fantasy Zone
94??Senjou no Ookami
95Namco ??Dragon Buster
96Bandai ??Oeka Kids
97??Kaiketsu Yanchamaru
99VS System 8KB VROM SwitchVS SMB, VS Excite Bike
105NES-EVENTNintendo World Championships
107??Magic Dragon
112AsderSango Fighter, Hwang Di
114??The Lion King
115??Yuu Yuu Hakusho Final
117??San Guo Zhi 4
118MMC3-TLSROM/TKSROM BoardYs 3, Goal! 2, NES Play Action Football
119MMC3-TQROM BoardHigh Speed, Pin*Bot
140Jaleco ??Bio Senshi Dan
144??Death Race
151Konami VS System ExpansionVS The Goonies, VS Gradius
152??Arkanoid 2, Saint Seiya Ougon Densetsu
153Bandai ??Famicom Jump 2
154Namco ??Devil Man
155MMC1 w/o normal WRAM disableThe Money Game, Tatakae!! Rahmen Man
156??Buzz and Waldog
157Bandai Datach ??Datach DBZ, Datach SD Gundam Wars, **EEPROM NOT SUPPORTED
158RAMBO 1 DerivativeAlien Syndrome
180??Crazy Climber
182??Super Donkey Kong
184??Wing of Madoola, The
189??Thunder Warrior, Street Fighter 2 (Yoko)
193Mega SoftFighting Hero
202Multi-cart(bootleg)150 in 1
203Multi-cart(bootleg)35 in 1
207Taito ??Fudou Myouou Den
208??Street Fighter IV (by Gouder)
209??Mortal Kombat 3 - Special 56 Peoples
210Namco ??Famista '92, Famista '93, Wagyan Land 2
225Multi-cart(bootleg)58-in-1/110-in-1/52 Games
228Action 52Action 52, Cheetahmen 2
230Multi-cart(bootleg)22 Games
232BIC-48Quattro Arcade, Quattro Sports
234Multi-cart ??Maxi-15
235Multi-cart(bootleg)Golden Game 150 in 1
240??Gen Ke Le Zhuan, Shen Huo Le Zhuan
242??Wai Xing Zhan Shi
246??Fong Shen Ban
248??Bao Qing Tian
249Waixing ????
250??Time Diver Avenger
255Multi-cart(bootleg)115 in 1


FCE Ultra supports the following UNIF boards. The prefixes HVC-, NES-, BTL-, and BMC- are omitted, since they are currently ignored in FCE Ultra's UNIF loader.

Name:Game Examples:
MARIO1-MALEE2Super Mario Bros. Malee 2
NovelDiamond9999999in1Novel Diamond 999999 in 1
Super24in1SC03Super 24 in 1
Supervision16in1Supervision 16-in-1
Sachen-8259ASuper Cartridge Version 1
Sachen-8259BSilver Eagle
Sachen-74LS374NAuto Upturn
SA-016-1MMaster Chu and the Drunkard Hu
SA-72008Jovial Race
SA-0036Mahjong 16
SA-0037Mahjong Trap
TC-U01-1.5MChallenge of the Dragon
8237Pocahontas Part 2
SAROMDragon Warrior
SBROMDance Aerobics
SGROMDefender of the Crown
SKROMDungeon Magic
SLROMCastlevania 2
SL1ROMSky Shark
SNROMShingen the Ruler
SOROMNobunaga's Ambition
TFROMLegacy of the Wizard
TGROMMegaman 4
TKROMKirby's Adventure
TLROMSuper Spike V'Ball
TSROMSuper Mario Bros. 3
TVROMRad Racer 2
ELROMCastlevania 3
ETROMNobunaga's Ambition 2
EWROMRomance of the Three Kingdoms 2
HKROMStar Tropics
Nintendo Discrete Logic:
GNROMSuper Mario Bros./Duck Hunt
NROM-128Mario Bros.
NROM-256Super Mario Bros.

Famicom Disk System

You will need the FDS BIOS ROM image in the base FCE Ultra directory. It must be named "disksys.rom". FCE Ultra will not load FDS games without this file.

Two types of FDS disk images are supported: disk images with the FWNES-style header, and disk images with no header. The number of sides on headerless disk images is calculated by the total file size, so don't put extraneous data at the end of the file.

If a loaded disk image is written to during emulation, FCE Ultra will store the modified disk image in the save games directory, which is by default "sav" under the base directory.

Game Genie

The Game Genie ROM image is loaded from the file "gg.rom" in the base directory the first time Game Genie emulation is enabled and a ROM image is loaded since the time FCE Ultra has run.

The ROM image may either be the 24592 byte iNES-format image, or the 4352 byte raw ROM image.

Remember that enabling/disabling Game Genie emulation will not take effect until a new game is loaded(this statement shouldn't concern any of the "run once" command-line driven builds).

VS Unisystem

FCE Ultra currently only supports VS Unisystem ROM images in the iNES format. DIP switches and coin insertion are both emulated. The following games are supported, and have palettes provided(though not necessarily 100% accurate or complete):

Automatic IPS Patching

Place the IPS file in the same directory as the file to load, and name it filename.ips.

        Examples:       Boat.nes - Boat.nes.ips
                        Boat.zip - Boat.zip.ips
                        Boat.nes.gz - Boat.nes.gz.ips
                        Boat     - Boat.ips

Some operating systems and environments will hide file extensions. Keep this in mind if you are having trouble.

Patching is supported for all supported formats(iNES, FDS, UNIF, and NSF), but it will probably only be useful for the iNES and FDS formats. UNIF files can't be patched well with the IPS format because they are chunk-based with no fixed offsets.

Using FCE Ultra

Key Assignments

F5Save state.
F7Load state.
0-9Select save state slot.
Shift + F5Record movie.
Shift + F7Play movie.
Shift + 0-9Select movie slot.
F9Save screen snapshot.
F4Hide sprites(toggle).
Shift + F4Hide background data with overscan color(toggle).
Alt + EnterToggle fullscreen mode.
F11Hard reset(toggle power switch).

VS Unisystem

F8Insert coin.
F6Show/Hide dip switches.
1-8Toggle dip switches(when dip switches are shown).

Famicom Disk System

F6Select disk and disk side.
F8Eject or Insert disk.

Barcode Readers

0-9Barcode digits(after activating barcode input).
F8Activate barcode input/scan barcode.

Game Pad

These default Game Pad key assignments do not apply to the Win32-native port. See the table below this for the Win32-native port's default game pad mappings.
Key:Button on Emulated Gamepad:
Keypad 2B
Keypad 3A

Win32-native Port
Key:Button on Emulated Gamepad:
Left ControlB
Left AltA
Cursor DownDown
Cursor UpUp
Cursor LeftLeft
Cursor RightRight

Power Pad

Side B
OP []

Side A
P [

Family Keyboard

All emulated keys are mapped to the closest open key on the PC keyboard, with a few exceptions. The emulated "@" key is mapped to the "`"(grave) key, and the emulated "kana" key is mapped to the "Insert" key(in the 3x2 key block above the cursor keys).

To enable or disable Family Keyboard input, press the "Scroll Lock" key. When Family Keyboard input is enabled, FCE Ultra will also attempt to prevent any key presses from being passed to the GUI or system.

HyperShot Controller

Controller IQW
Controller IIER

Mahjong Controller

Emulated Mahjong Controller:ABCDEFGHIJKLMN

Emulated Mahjong Controller:SELST?????

Quiz King Controller

Emulated Buzzer:123456
PC Keyboard:QWERTY


FCE Ultra supports arguments passed on the command line. Arguments are taken in the form of "-parameter value". Some arguments are valueless. Arguments that have both a parameter and a value will be saved in the configuration file, with the exception being the network-play arguments. Please note that most of these arguments are currently not recognized on the Win32-native port.

Argument:Value Type:Default value:Description:
-cpalette xstring0Load a custom global palette from file "x". Specifying "0" will cause FCE Ultra to stop using the custom global palette.
-ntsccol xboolean0If value is true, enable automatic generation and use of an NTSC NES' colors.
-pal xboolean0If value is true, emulate a PAL NES. Otherwise emulate an NTSC NES.
-sound xboolean1If value is true, enable sound emulation and output.
-soundrate xinteger48000Specifies the sound playback rate, in frames per second("Hz").
-soundvol xinteger100Sound volume.
-soundq xboolean0If value is true, enable high-quality sound emulation.
-soundbufsize xinteger24(52 for Win32)Specifies the desired size of the sound buffer, in milliseconds.
-inputcfg xstringConfigure mapping of physical device inputs to a virtual device. Valid values are "gamepad1", "gamepad2", "gamepad3", "gamepad4", "powerpad1", "powerpad2".
-input1 x
-input2 x
stringgamepadSelect input device for input port 1 or 2. Valid strings are "none", "gamepad", "zapper", "powerpada", and "powerpadb".
-fcexp xstringnoneSelect Famicom expansion port device. Valid strings are "none", "shadow", "arkanoid", "4player", and "fkb".
-nofs xboolean0If value is true, disable four-score emulation.
-gg xboolean0Enable Game Genie emulation.
-snapname xboolean0If value is true, use an alternate naming scheme(file base and numeric) for screen snapshots.
-frameskip xinteger0Specifies the number of frames to skip(emulation and drawing) for each frame emulated and drawn. The frameskipping code will not work properly with light-gun games, and it may break other games as well, so use it with this knowledge in mind!
-nothrottle xboolean0If value is true, disable the speed throttling that is used when sound emulation is disabled.
-clipsides xboolean0If value is true, clip leftmost and rightmost 8 columns of pixels of the video output.
-slstart xinteger8 First scanline to be rendered in NTSC emulation mode(when PAL emulation is disabled).
-slend xinteger231 Last scanline to be rendered in NTSC emulation mode.
-slstartp xinteger0 First scanline to be rendered in PAL emulation mode.
-slendp xinteger239 Last scanline to be rendered in PAL emulation mode.
Argument:Value Type:Default value:Description:
-opengl xboolean1Enable OpenGL support(if the support has been compiled in).
-openglip xboolean1Use bilinear interpolation when using OpenGL.
-special(-specialfs) xinteger0(0)Use special video scaling filters.
  • 1 = hq2x
  • 2 = Scale2x
  • 3 = hq3x
  • 4 = Scale3x
-stretchx/-stretchy xboolean1/0Stretch to fill surface on x or y axis(fullscreen, only with OpenGL).
-doublebuf xboolean0Request double buffering(note that double buffering or sync-to-vblank may be forcibly enabled by your video drivers).
real2.50(2)/2(2)Specify the scaling factor for each axis. Factors will be truncated to integers when not using OpenGL.
-xres x/-yres yinteger640/480Set the desired horizontal/vertical resolution when in fullscreen mode.
-efx(fs) xinteger0Specify simple special effects, represented by logically ORing constants. 1=scanlines, 2=TV Blur
-fsboolean0Full screen mode.


\Firebug\High-level mapper information.
Andrea MazzoleniScale2x/Scale3x scalers included in FCE Ultra.
BeroOriginal FCE source code.
Brad TaylorNES sound information.
Chris HickmanArchaic Ruins.
Donald MooreDC PasoFami NES packs.
Fredrik OlsonNES four-player adapter information.
Gilles VollantPKZIP file loading functions.
gorohVarious documents.
Jeremy ChadwickGeneral NES information.
Justin SmithGood stuff.
Kevin HortonLow-level NES information and sound information.
KiVarious technical information.
Mark KnibbsVarious NES information.
Marat FayzullinGeneral NES information.
Matthew ConteSound information.
Maxim Stepinhq2x and hq3x scalers included in FCE Ultra.
noriFDS sound information.
QuietustVRC7 sound translation code by The Quietust (quietust at ircN dort org).
R. HoelscherFamicom four-player adapter information.
Rob MoccaDC PasoFami NES packs, testing.
Sean WhalenNode 99
Tatsuyuki SatohOPL2 emulator used for the VRCVII sound emulation.
TheRedEyeROM images, testing.
...and everyone whose names my mind has misplaced.