NullDC4Wii - Dreamcast Emulator for Wii

a fork from https://github.com/skmp/nullDCe

TODO (Maybe you can help !)

Simple

Test current state with every game and report compatibility (see "compatibility" below)
Create presets for games
Test 2/3/4 player mode on wiimote & gamecube also, please report
Help me finding regression (NOT bugs or glitch, only regression for now please)
Comment / Guides / Documentation (WiiBrew Wiki)
Test and report Fishing Rod/USB Keyboard/Lightgun/Maracas support

Developer (Easy)

Controller correct layout, for pro pad and for gamecube pad
User custom Preset
Fishing Rod/USB Keyboard/Lightgun/Maracas support (probably unsupported now)
Put external config file for controllers (controls.cfg)
fix Volgarr regresion
DualShock 3 issue: left stick has the Y axis inverted, up is down, and down is up.
Custom layout : Chuchu rocket/Quake3 (bith Gamecube & wii)
Custom layout : a toggle to make the right analog stick with supported controllers act as buttons X (Left) - Y (Up) - A (Down) - B (Right). This is useful for twin stick shooters that use the diamond button layout for gameplay (like Xeno Crisis).
Add a winCE preset to prevent that game isn't supported
check fps_boost preset matching from cfg, seems not working

Developer (Normal)

4/3 support (implemented, need fix on some games like Shenmue)
Support for CHD/ELF game file
Return to file list (instead return to homebrew menu)
Synchronise Dreamcast clock to Wii's clock
Get RGB565_opaque_alpha AUTO mode
Get Offset color AUTO mode

Developer (Hard)

Fix Chuchu Rocket 16Bit PCM bug
Fix non WinCE games not launching (Rez, San Francisco 2049...)
Improve gxRend.cpp = main file about specific rendering for Wii
Splitting gxRend.cpp in multiple files ? (beware this is more tricky than it look)
Table convertion between SH4 Opcodes of SH4 and the WiiPPC ?
Use LLVM to port code for PowerPC ? (skmp says its not a good idea in this case)
Dynarec improvement (very performant right now, but if we can find boost...)
WinCE Games support #37

Installation

Put BIOS file and game file

Mandatory BIOS files in SD:/data/

dc_boot.bin
dc_flash.bin
fsca-table.bin (included)

Optional BIOS files in SD:/data/

dc_flash_wb.bin (this is the dc_flash but already saved)
syscalls.bin (needed for elf/bin)
IP.bin (needed for elf/bin)

dc_nvmem.bin
vmu_default.bin

Game file in SD:/discs/ or USB:/dreamcast/

Test with castlevania Resurrection and Sega Tetris to begin with

Put your folders with GDI in this directory. CDI also works

Might work for ISO / BIN / CUE / NRG / MDS

BIN/CUE/ELF, but you probably need IP.bin/syscalls.bin (take IP.TMPL from bootdreams and rename it IP.Bin)

Configuration

General configuration

Check nullDC.cfg at root

Controls

Dreamcast	Wiimote	Wiimote (ChuChu Rocket!)	Gamecube	Gamecube (ChuChu Rocket!)
A	A	down & A	A	A
B	B	right & B	B	X
Y	1	up	Y	Y
X	2	left	X	B
START	Home	Home	START	START
D-PAD	D-PAD	- no implementation -	D-PAD	D-PAD
STICK	Nunchuck Stick	Nunchuck Stick	STICK	STICK
L	- (and Nunchuck Z)	- (and Nunchuck Z)	L	L
R	+	+	R	R
To Exit	- and +	- and +	R + L + Z	R + L + Z

Exit :
Press - and + (wiimote) or Press L + R + Z (or L + R + Start)

VMU (Memory card)

It seems to be supported, but 1rst you'll need to format the VMU in the bios

Files appears at root of /data/ :

vmu_save_A1.bin
vmu_save_A2.bin

Compatibility

https://wiibrew.org/wiki/NullDC4Wii/Compatibility

Presets

Presets are grouped in the in-emulator menu across 6 pages. The order below follows that exact same order (Page 1 to Page 6).

Page 1 : General

RATIO

Mode	Settings	Rendering
ORIGINAL	4/3 pillarbox	Original Dreamcast ratio
FULLSCREEN (default)	Stretched to fill screen	Fullscreen
AUTO	Picks by console aspect ratio setting (4:3 console → full width, 16:9 console → pillarbox)	Depends on console setting

SPEED LIMITER

Mode	Settings	Rendering
OFF (uncapped)	Emulator can run above 100% speed	Uncapped
ON (cap 100%)	Stops speed exceeding 100%	Capped

SHOW FPS

Mode	Settings	Rendering
OFF	No overlay	Nothing displayed
ON	Displays gameplay FPS and speed overlay	Overlay shown

🖼️ Graphics Preset

OLD Behavior (Before alpha0.64) :

Mode	Settings	Best platform
LOW	`GX_NEAR` · `lod_bias 0.0f` · `GX_DISABLE`	Wii
NORMAL (default)	`GX_LINEAR` · `lod_bias 0.0f` · `GX_DISABLE`	Wii
HIGH	`GX_LINEAR` · `lod_bias -0.5f` · `GX_ENABLE` · Anisotropic x2	Wii U
EXTRA	`GX_LINEAR` · `lod_bias -0.75f` · `GX_ENABLE` · Anisotropic x4	Wii U

The visual difference is limited for NORMAL/HIGH/EXTRA

NEW behavior (from alpha 0.64) :

Mode	Settings
LOW	`GX_NEAR`
NORMAL (default)	`GX_LINEAR`

Use LOW for 240p games/modes
Use NORMAL for other games

Important note : LOW can cause Z-Fighting (example in jet set radio, see #115)

TEXTURE CACHE

Mode	Settings	Rendering
VERY_FAST	skmp original algorythm (magic numbers). Buggy in most games	Max FPS
FAST	Best performance/accuracy in most case	Almost Max FPS
NORMAL (default)	Display mostly correctly	Good FPS
QUALITY (SLOW)	Best accuracy. Display correctly	Mid FPS

Can have huge FPS impact, try to have the lowest parameter.

4BPP MODE / 8BPP MODE

Mode (4BPP/8BPP)	Settings	Rendering
I4_STUB/I8_STUB	Dummy algorythm	Some element doesn't display at all, for max FPS
OPTIMIZED	Served as test, in the end CI4/CI(FAST) is better	Very good FPS
CI4 (FAST)/CI8 (FAST)	Best performance/quality	Very good FPS
CI4 (NORMAL)/CI8 (NORMAL)	Advanced algorythm for CI4/CI8	Mid FPS
RGB565 (ACCURATE)	Most advanced algorythm	Can have massive FPS dropdown (1 FPS) on some games

FRAMESKIPPING

Mode	Settings	Rendering
0 (default)	No frame skipped	Every frame drawn
1	Skip 1 frame	Faster, less smooth
2	Skip 2 frames	Faster still, less smooth
AUTO	Skips frames automatically depending on load	Adaptive

Still on testing, doesn't have the expected effect for now

2D FRAMEBUFFER

Mode	Settings	Rendering
NO (default)	Disable	Standard rendering
YES	Enable 2D framebuffer	Try for 2D games

Still on testing

ADVANCED_ALPHA

Mode	Settings	Rendering
NO	basic alpha threathment	Not accurate
YES (default)	additionnal alpha threatment	Near perfect

Mostly for debug. Should always be on

> BLEND_MODE

Mode	Settings	Rendering
OFF (LEGACY)	Disable	Not accurate
ON (CORRECT) (default)	Activate BLEND_MODE	Accurate, correct for Resident Evil 3

If flickerings, try turning off

Note : ADVANCED ALPHA needs to be on for BLEND_MODE

>> FPS_BOOST

Mode	Settings	Rendering
OFF (CORRECT) (default)	Disable	Accurate
ON (FASTER)	+2 FPS in BLEND MODE, to the cost of wrong Alpha/Transparency	Not Accurate

note : ADVANCED ALPHA and BLEND_MODE needs to be on for FPS_BOOST

PUNCH THROUGH

Mode	Settings	Rendering
OFF (faster)	Legacy: PT polys drawn last in TR blend state	Faster, less accurate
ON (correct)	OP → PT → TR order + PT_ALPHA_REF alpha test	Correct PT list alpha test

Needed in lot of games

TRANS_SORT

Mode	Settings	Rendering
OFF (default)	Disable	not Accurate (faster)
ON	can display stuff	Accurate

Can resolve flickering in some games Needed in lot of games

RENDER TO TEX

Mode	Settings	Rendering
OFF (faster)	RTT frames dropped (legacy)	Faster, mirrors/TV screens missing
ON (correct)	EFB copied back into VRAM	Correct mirrors/TV screens

Needed in some games

SPLIT SCREEN

Mode	Settings	Rendering
OFF (faster)	Every render pass presented fullscreen (legacy)	Faster
ON (correct)	Partial-clip passes scissored, presented once per vblank	Correct 2P viewports, e.g. Daytona USA

Needed for 2 players splitscreen or any 2 camera angle games.

Page 2 : Graphics

FMV FORMAT

Mode	Settings	Rendering
CMPR (DXT1)	Compressed format	Use if some movie displays white
RGBA8	Uncompressed, full quality	Slower
RGB565 (default, faster)	Uncompressed, no alpha	Faster

Vertex Color

Mode	Settings	Rendering
OFF (grey scale)	Grey Scale	Grey scale (a tiny bit faster)
ON (default)	Intensity color	Accurate

Color some pixel (Used in Jet Set Radio Future and Crazy Taxi 1/2)

DECAL_ALPHA

Mode	Settings	Rendering
OFF (faster, default)	no decal alpha	Not accurate
ON (correct)	Decal alpha implemented	Accurate, fixes Crazy Taxi's cars

See more : #68

SEAM FIX

Mode	Settings	Rendering
OFF (a bit faster)	Disable	Thin black seam lines between 2D tiles/sprites remain
ON (default)	Half-texel UV inset	Fixes black lines between 2D tiles

Use this or LOW to fix seam lines. See #18

Warning : ON causes a bug with Vertex Displacement (water mostly) : #119

BG POLYGON

Mode	Settings	Rendering
OFF (faster, default)	v0 color used for EFB clear only, no background quad drawn	Faster
ON (correct)	Barycentric-extrapolated background quad drawn	Correct bg gradient/texture, e.g. Who Wants to Be a Millionaire

RGB565 ALPHA

Mode	Settings	Rendering
OFF (fmt0 only, default)	Only fmt0 (ARGB1555) forced opaque	Correct for POD 2
ON (fmt0+fmt1)	Force opaque for fmt0(ARGB1555)+fmt1(RGB565)	Turn off for POD 2

May disapear in a future

LAYER SORT

Mode	Settings	Rendering
OFF (legacy, default)	Disable	Standard sort
ON (TR tier sort)	Layer-tiered translucent sort	For 2D scenes drawn at ONE depth

Helps determine what should be front and back trough looking at texture format/properties. For games that submit their whole 2D scene at a single depth and rely on the Dreamcast's per-pixel autosort: background plates draw first, then stage art, then stage sprites, then everything else. Game-agnostic — used by Hokuto no Ken and Street Fighter III. Was part of the HOKUTO HACK before alpha0.66.

JOJO FIX

Mode	Settings	Rendering
OFF	Disable	Pre-fix behavior
ON (default)	Enable fix	For JoJo's Bizarre Adventure

Has to be used with CI4_FAST/CI8_FAST to reduce massive FPS drop in battle. May use the same technique in other games.

Page 3 : Depth & Width

DEPTH_CLIP

Mode	Settings	Rendering
OFF (legacy)	XF Z-clipping on, no near margin	2D/menus can be invisible on real Wii
NEAR MARGIN (Wii, default)	Pads vtx_min_Z 0.1% so the nearest 2D layer can't land exactly on the near clip plane	Recommended for Wii
NO CLIP (Dolphin)	Matches Dolphin: out-of-range depth clamps instead of the poly vanishing	Matches Dolphin behavior

It's basically like FIXED_DEPTH, leave it to NEAR MARGIN

FIXED_DEPTH

Mode	Settings	Rendering
NO (default)	Disable	Good
WIDE	can help display some stuff - mostly for debug	Bad
TIGHT	can help display some stuff	Good

FIXED_DEPTH can help flickering and Z-Fighting

HUD_PASS

Mode	Settings	Rendering
NO (default)	-	Not active
Overlay	Help hud to display when FIXED_DEPTH is on TIGHT	accurate
Protect	Help hud to display when FIXED_DEPTH is on TIGHT	Perfect
Mostly needed if Fixed Depth is set to tight

X SCALER

Mode	Settings	Rendering
OFF (legacy)	PVR SCALER_CTL.hscale support disabled	Standard
ON (default)	PVR SCALER_CTL.hscale support	ON for Omicron / Wacky Races (render 1280 wide, scaler halves 2:1)

For Nomad Soul and Wacky Racer. Maybe other games

CANVAS WIDTH

Mode	Settings	Rendering
OFF (640, legacy, default)	Legacy 640 canvas	Standard
Custom value	Forces canvas width in 240p modes	e.g. SF3 Double Impact = 384 (the CPS3 arcade width)

See compatiblity wiki for more info

PPZ_WRITE : PER POLYGON Z WRITE

Mode	Settings	Rendering
NO	No Per Polygon Z Write	More compatible
YES (default)	Per Polygon Z Write	More accurate

Try putting NO if you experience troubles, with HUD for example.

Page 4 : Audio

AUDIO BUFFERS

Mode	Settings	Rendering
DEFAULT (saved)	Leaves the value at its cfg/UI setting	Depends on saved config
0 (never block)	Never blocks/drops on overrun	Fastest, most likely to drop
1 / 2	Blocks until below N queued buffers	More paced
3 (most paced)	Most conservative pacing	Most paced, safest

Put audio buffers = 1 generally leads to good audio. To the cost of FPS unfortunatly.

CDDA MUSIC

Mode	Settings	Rendering
OFF	CD audio tracks silent	No CD music
ON (default)	GD-ROM Red Book audio fed to the AICA mixer	CDDA music plays in games

MUTE 16BIT PCM

Mode	Settings	Rendering
OFF (legacy, default)	All AICA sample formats audible	Standard
ON (silence 16B)	16-bit PCM channels silenced at KEY_ON	Fixes ChuChu Rocket's echoey 16-bit SFX (also mutes any other 16-bit music/voices, so game-specific)

Page 5 : Core / Special Hack

🧮 Calculation Accuracy Preset

Mode	Description
FAST (default)	Maximum FPS (higher frame rate), less loading times
BALANCED	Good balance between speed and accuracy
ACCURATE	Closest behavior to original hardware

If you experience Freeze in some heavy games like Shenmue, put FAST or BALANCED. FAST may be the default setting in future versions

If you experience various bugs (example that may happens : weird AI controled NPC, weird timing) put ACCURATE

ASYNC_RENDER

Mode	Settings	Rendering
OFF (legacy)	CPU blocks in GX_DrawDone until the GPU finishes each frame	0 frame latency
ON (faster, default)	Frame queued, presented one vblank later; SH4 emulates while GPU draws	Faster, to the cost of 1 frame input-lag

ASYNC_RENDER is generally faster. Can resolve flickering. Works better on real hardware than dolphin

RENDER DELAY

Mode	Settings	Rendering
OFF (faster, default)	Legacy: instant list-complete IRQs	Faster
ON (hw-like)	Hardware-like staggered ISP/TSP/Video timings	ON for MvC2 and CvSNK

TMEM CACHE

Mode	Settings	Rendering
OFF (legacy)	Full GPU texture cache invalidate every frame	Standard
ON (faster?, default)	Invalidate only on texture re-decode	Keeps GPU texture cache warm

Haven't seen any effect but keeping on for now

SH4 CLOCK

Mode	Settings	Rendering
200MHZ (full, default)	Nominal Dreamcast speed	Full speed
Underclock (150-200MHz, step 5)	Lower value = fewer emulated cycles per real second	Lower = faster host, slower game

Underclocking is supposed to raise FPS. Didn't see any difference

ARM7 SPEED

Mode	Settings	Rendering
10MHZ (default)	Sound CPU at normal speed	Standard audio
5MHZ (faster)	Underclocked sound CPU	Faster, check audio!
2.5MHZ (risky)	Heavily underclocked sound CPU	Risky, check audio!

5 mhz generally works and bring FPS boost

JIT SBP

Mode	Settings	Rendering
OFF	No stale/self-modified block guard	Fastest, riskiest
KNOWN (default)	Guards known self-modifying regions	Balanced
ALL RAM (slow)	Guards all RAM	Safest, slowest

Generally work, no difference

FASTMEM

Mode	Settings	Rendering
OFF (legacy)	Standard PPC-MMU memory access	Slower
ON (faster, default)	Branchless JIT MMU-mapped memory access	Faster

Crash observed in Re-Volt when launching a race. Only game that does that for now.

JIT BCACHE

Mode	Settings	Rendering
OFF (legacy, default)	Legacy dynamic-branch dispatch	Standard
ON (flat)	Flat, 1-cacheline dynamic jump dispatch	Faster dispatch

L1/L2 cache related. Can help heavy scene with Fast cache like in Shenmue intro maybe

FPU PIN

Mode	Settings	Rendering
OFF (legacy, default)	fr0-15 not pinned	Standard
ON (experimental)	Pins fr0-15 to real PPC FPU registers f14..f29	Experimental, Floating Point Unit related

Can help heavy scene with Fast cache like in Shenmue intro maybe

JIT ALIGN

Mode	Settings	Rendering
OFF (legacy, default)	No block alignment	Standard
ON (32B lines)	Pads every SH4-dynarec block entry to a 32-byte L1 cache line	Better cache hygiene, L1/L2 cache related

L1/L2 cache related. Can help heavy scene with Fast cache like in Shenmue intro maybe

Page 6 : Experimental/Debug

These doesn't make any change, or usually worse.

MIPMAPS

Mode	Settings	Rendering
OFF (fastest, default)	No mip chain	Fastest, more shimmer far away
FAST	Generated GX mip chain + nearest-mip bilinear	Less shimmer far away
TRILINEAR (slow)	Best quality	Best quality, halves texture fill rate (e.g. -40% in Test Drive 6)

OFFSET COLOR

Mode	Settings	Rendering
OFF (legacy, default)	Offset/specular color dropped	Standard
ON (correct)	PIX = base*tex + offset via 2nd TEV stage	Correct specular highlights

May cause white surface on some games (ie = berserk, Tokyo highway challenge...)
May fix black surface on some games (ie = sega worldwide soccer)

ISP_DEPTH_FUNC

Mode	Settings	Rendering
OFF (legacy, default)	Disable	Standard
ON (opaque/PT)	Per-poly depth test on opaque/PT lists	Experimental
ON (all lists)	Per-poly depth test on all lists	Experimental

ISP_CULL

Mode	Settings	Rendering
OFF (legacy, default)	Disable	Standard
ON	Per-poly backface cull	Experimental
ON (swap winding)	Per-poly backface cull, two cullable windings swapped	Experimental

AUTOSORT

Mode	Settings	Rendering
OFF (legacy, default)	Disable	Standard
N layers (slow)	Real per-pixel PVR autosort via GX depth peeling, N = max translucent depth layers per pixel	Very GPU-heavy (~2 extra TR walks + 2 EFB Z copies per layer) — per-game only

DMA FIX

Mode	Settings	Rendering
OFF (legacy)	Disable	Standard
ON (default)	ch2/PVR/Sort/AICA-G2 DMA correctness fixes	Fixes related to loading CDI/GDI file

SCHED (ORDER)

Mode	Settings	Rendering
OFF (cascade, default)	Legacy cascade scheduling	Standard
ON (deadline)	Unified cycle-deadline scheduler	Hardware-order DMA/IRQ completions, related to loading CDI/GDI file (experimental)

HOKUTO HACK

Mode	Settings	Rendering
OFF (legacy, default)	Disable	Standard sort
ON (HnK addresses)	Hardcoded RAM address hack	Specific fix for Hokuto no Ken

Refines LAYER SORT using Hokuto no Ken's own VRAM texture addresses, for the debris tiles that texture format/properties alone cannot tell apart from the fighters. Needs LAYER SORT on — it does nothing by itself — and only works for stage 1/2 at the moment. Leave it off in every other game.

SH4 CORE

Mode	Settings	Rendering
INTERPRETER	Interpreted SH4 core	Slow, for debugging only
DYNAREC (default)	JIT recompiler	Fast

Game Specific Presets

LAYER SORT (Hokuto No Ken, Street Fighter III) helps determine what should be front and back trough looking at texture format/properties. HOKUTO HACK adds to it a RAM address check for a few Hokuto no Ken textures that those properties cannot separate — Hokuto no Ken only, and it needs LAYER SORT on.

JOJO FIX (Jojo's Bizarre adventure) has to be used with CI4_FAST to reduce FPS drop in battle. May use the same technique in other games

Vertex color is a special method on Dreamcast to color stuff. Notable example in Crazy Taxi : The arrow and dollar sign are Vertex Colored. You will notice the cars too : They will add to the current texture so the same car with the same texture will appear red, blue, green, etc...

Same for Jet Set Radio, will add color to the logo.

See Compatiblity guide for hints depending of the games

game_presets.cfg

game_presets is a file that reads the file name and directly apply matching presets.

game_presets.cfg needs to be in sd:/discs/

With recent version, multiple file names are suppported :

[crazytaxi2][crazy taxi 2] ; more specific first
depth_clip=1
tex_cache=normal
vertex_color=off

[crazytaxi][crazy taxi]
depth_clip=1
tex_cache=normal
graphics=normal

So in that configuration, your file name should be crazytaxi.gdi or crazytaxi.gdi

I'm not enterely sure spaces are supported right now

Maybe it needs to be more specific, so in this example, just add [crazytaxi1] like this :

[crazytaxi][crazytaxi1][crazy taxi]

Then rename your gdi crazytaxi1.gdi or crazytaxi1.cdi

If everything is correct, in the option menu, you should see something like this :

Creating the optimal Preset :

Best thing to do :

1/ Launch with default preset
2/ play a little bit the game (default stage, just input A A A), 2/3 minutes is enough
3/ If some things doesn't display good, try to change settings. Already we know that works :

fine (seam) lines in 2D sprites : put "LOW" as graphics
Z fighting : put FIXED DEPTH to "tight"
2 player viewport (or 2 cameras in the same scene) = SPLITSCREEN

4/ Flickering, fix can be :

BLEND_MODE (set to off)
TRANS_MODE (set to off)
ASYNC_RENDER (set to on)
DEPTH-CLIP (set to tight)

5/ Other graphical things not displaying (or black screen) : try flipping all the other setting, particulary :

4BPP/8BPP to CI4_FAST or CI8_FAST
BG POLYGON to on
PUNCH Trough to ON
TRANS_SORT to ON
RENDER TO TEX to ON
2D Famebuffer = ON

6/ off Canvas problem (screen too small or too big)

try xratio = on (or off)
CANVAS_WIDTH (try different values)

7/ Restart the game, try CACHE_VERY_FAST and CACHE_FAST. Find the lowest compatible option for the game. They may crash heavy-scene thus, like Shenmue intro

8/ Try if FPS_BOOST is possible and don't break too much the game

9/ If you want to dig more, try the game in early version of NullDC4Wii :

alpha0.25
alpha0.28
alpha0.40

Report to me if you seen any regressions

Some examples of common problems :

Fine (seam) lines in 2D example :

CACHE related problem examples :

Off Canvas :

Z Fighting example :

Fastmem crash example :

For Developpers :

Compilation Process (Windows)

0/ Download/clone source code

1/ Install devkitpro/devkitPPC

https://wiibrew.org/wiki/DevkitPPC

Just tick PPC (not ARM, x86, etc).

See this issue : #13

2/ Launch MSys2 terminal

Devkitpro has it's own UNIX terminal, by default it's located here :
C:\devkitPro\msys2\usr\bin\mintty.exe

3/ Install additional development packages :

pacman -Syu # updates MSYS2 and package database
pacman -S wii-dev

4/ PATH & System variable configuration (Windows)

PATH

In windows variable environnement add C:\devkitPro\devkitPPC\bin to Uservariable PATH

UPDATE MARCH 2026 : This folder seems to be needed also for elf2dol : C:\devkitPro\tools\bin

System variables

Modify these system variable

DEVKITPPC : C:\devkitPro\devkitPPC
DEVKITPRO : C:\devkitPro\

Strongly advise you to completly reboot Windows after that (not just relaunching CMD)

5/ launch wii/vs_make.bat in a standard CMD windows terminal

Correct errors if they are some errors

Use dollz3

dollz3 is a compress tool for *.dol files, and it is in the original "vs_make.bat" file, but it seems not to work

~~https://wiibrew.org/wiki/Dollz~~

Compilation Process (Linux & Mac)

It should work for Linux & Mac with similar process

Leaving this link for now :

https://wiibrew.org/wiki/DevkitPPC

Dolphin (for debug/testing)

Activate :

SD Card
Display FPS
For log, in config.ini add "DebugModeEnabled = True" under [Interface]
(optional) VSync eventually
(optional) Advanced > Debug > Texture Format Overlay

Frequently Asked Question (FAQ)

My SD Card isn't recognized

Make sure you have a good brand (Samsung, Kingston). Optimal card would be between 2Gb and 32Gb (more should work, we support SDXC), formated in FAT32 with 32kb cluster (16kb or 64kb could work). Try another SD card if that's not working

Games doesn't work

First, try on SD card with a know working game (Castlevania, Chuchu Rocket or Sega Tetris are best candidate).

My USB key/HDD isn't recognized

For USB, try a FAT32 USB key first (32kb cluster) before switching to any other device. It works on my 500HDD FAT32 for information (with a cluster of 4kb)

Does VMU work ?

It's reported working. Step 1 : go to bios. Step 2 : format VMU. Step 3 : exit properly the emulator (+ and -)

Why this emulator ?

Because why not ? At first it was a POC (Proof Of Concept) but digging more and more, it seems somes games are achievable to 100% speed (in PAL50 mode). So yeah !

What games does work ?

Please check the compatiblity Wiki : https://wiibrew.org/wiki/NullDC4Wii/Compatibility

Does it work on Wii U ?

We have a Wii U fowarder that also use the speed boot of the Wii U (overclock). A native port for Wii U could be done if someone wants to do port it.

Does it support Atomiswave ?

Not yet, this could ask between 0.03 and 0.5Mb of RAM. Doable yes, maybe not really worth the effort. But you can use Atomiswave hacks for dreamcast, lots of them do work.

Will it support NAOMI ?

Definitly not, the recent Dynarec/JIT (= fps boost) and ARM7 cache ask for more RAM, we have no more place to add 16Mb for NAOMI Ram

Controls are messy / this doesn't work / My Propad isn't recognize etc...

Open an issue, everything should be ok now

Will THAT AMAZING ADVENTURE GAME be considered as "Supported" one day ?

Probably not, this emulator prioritize multiplayer fun games to play friends with. Playing an adventure game like Shenmue or an RPG could be a very frustrating experience that I strongly do not recommand. Use Gamecube/Wii version (if it does exist) or a PC for emulation instead.

What can I do to help ?

Try different games, parameters and report in the compatibility wiki : https://wiibrew.org/wiki/NullDC4Wii/Compatibility

Is 100% speed of the emulator achievable on Wii ?

The only way to know this answer is to try our best ! Actually, some 2D games run 100% speed, and some 3D games also ! But we are mostly around 60 or 80% of speed...

We are still trying to improve performance, altough we already done a lot of amazing stuff :

Improved Dynarec
Fastmem
ARM7 CACHE

We also need to work more on TEV (Texture Environnement - a specialized hardware unit inside the graphics chip), it has been tested but only on dolphin. Maybe on real hardware this would have better result.

Another good strategy would be to really have a per-game specific emulator. That would take a long time, so for now we have presets & auto-presets implementation trough game_presets.cfg

Also, it's suggested we build a custom Dolphin-Emulator with some tools to help fine-tuning everything and gain more speed. More info here : #116

Is 100% speed of the emulator achievable on Wii U?

Probably ! Wii U has the additional CPU power we need. Test the overlocked fowarder !

Can it read Original games (GD-Rom) ?

The Wii can't read those disc format. Maybe if you change the optical drive and with some code implementation, but that's not worth it.

Can it read CDI/Utopia disc ?

Maybe it's possible, but we don't have time to focus on this. CDI Files on SD Card/USB are supported since alpha 0.28 anyway.

Will WinCE games be implemented ?

That an additionnal ressources in CPU and we are limited. That may would make sense for a WiiU Port.

We are currently testing a branch with some implementation but it doesn't seem to work.

Will Retroachievement be implemented ?

Probably not, we are super tight on RAM, and it also cost 1/2% of cpu cycle

Will Netplay be implemented ?

Probably not, again, we are very short on RAM/CPU. And on Wii we don't have the 100% speed everytime.

How is AI involved in the project ?

Since I (BenoitAdam) digged the NullDC code, AI has been heavily used to make improvement to the emulator. The very first state of the emulator (alpha 0.02) is 99% hand written code by SKMP and NullDC contributors at the time. Only some few changes have been made to be able to recompile it and make it run. Various AI are used : MistalAI/ChatGPT/Codex/Claude and Deepseek. Claude is very convenient because of artifact and Claude Code. Gemini helped on some improvements, and Deepseek too.

I hate AI !

It's ok, you have the right, but without AI this project wouldn't have been resurected. AI for code is really a big help, definitly not the same thing with AI generated images and videos. For information AI for image ask ~10x more power, AI for video ask ~100x more power. A Wii is also using 20x less power than a PS4/PS5.

Reduce CO2 emission & grow trees is the plan for the planet. Also prevent stupid people throwing their cigarett butt & firmly condemn pyromaniacs.

Do you have a discord ?

Yes : https://discord.gg/sJst6jmQyH

Do you accept donation ?

Yes ! Initially I was against donation but spending this much time & effort (and sometimes money) to this project led me to ask for donation. Not trying to getting rich, just staying afloat.

Buy Me a Coffee / Ko-Fi

This is very popular amongst small dev project, I don't know what's the difference or if some people would prefer one over the other one, anyway here are the links :

Patreon

The classic "Patreon" subscribing is here :

https://www.patreon.com/cw/NullDC4Wii

Paypal

For those used to Paypal, the link is here : https://www.paypal.com/ncp/payment/2NE7AYS77K6AJ

Ressources

Dreamcast Emulators

NullDC https://code.google.com/archive/p/nulldc/source/default/source
NullDC (github) https://github.com/skmp/nullDCe
NullDC for PSP : https://github.com/PSP-Archive/nulldce-psp
NullDC for Xbox360 https://github.com/gligli/nulldc-360
Reicast : https://github.com/skmp/reicast-emulator
Flycast : https://github.com/flyinghead/flycast
Deecy : https://github.com/Senryoku/Deecy Redream : http://redream.io/

Devkitpro

Main website : https://devkitpro.org
GitHub : https://github.com/devkitPro
Installer (releases) : https://github.com/devkitPro/installer/releases
Wii Examples : https://github.com/devkitPro/wii-examples

libOGC

GitHub (Wii/GameCube system librairy) : https://github.com/devkitPro/libogc

Emulators

Dolphin Official Website : https://dolphin-emu.org
GitHub (for timings Gekko/CPU) : https://github.com/dolphin-emu/dolphin

Wiibrew Wiki

Emulation Page : https://wiibrew.org/wiki/Emulation
Homebrew tutorials : https://wiibrew.org/wiki/Main_Page

Media Coverage

France :
https://www.programmez.com/actualites/programmez-numero-gaming-et-developpement-de-jeux-est-disponible-39720

Italy :
https://www.biteyourconsole.net/2026/05/13/nulldc4wii-alpha-v0-22-porta-il-dreamcast-su-wii-con-supporto-usb-multiplayer-e-miglioramenti-prestazionali/

Credits

skmp (original NullDC creator)
NullDC contributors
Joseph Jordan - libiso
Xale00 (also know as Benoit Adam) - 2026 recompilation
gligli (Xbox 360 port)
Xeihro (Xiro28 PSP Port)
AI because this project would have never existed otherwise lol
Probably Reicast/Flycast Team also
Welcome to the IA-age guys and good luck everyone.

All together, let's Cast the Dream.

Special thanks

skmp because he's the god
Senryoku, develloper of Deecy emulator
OriginalDave, developer of Jocasta
MetalliC, developer of Demul
Dolphin Team, would have been a pain to test on real hardware everytime otherwise
devkitPPC/Libogc
Everyone helping on emuvdev/discord
Jilou04 for constantly testing on Wii U and reporting
All testers and all futur testers
People actually helping me on the wiibrew wiki

Special no thanks

To all people not believing in this project
People constantly critisizing the fact AI is used in this project (this project wouldn't have existed otherwise...).

Name		Name	Last commit message	Last commit date
.github		.github
.vscode		.vscode
apps		apps
archive		archive
cl		cl
config		config
dc		dc
emitter		emitter
plugins		plugins
plugs		plugs
wii		wii
workdir		workdir
.gitignore		.gitignore
CMakeLists.txt		CMakeLists.txt
CMakeREADME.txt		CMakeREADME.txt
FPS_GOAL.md		FPS_GOAL.md
LICENSE		LICENSE
README.md		README.md
SKILL.md		SKILL.md
config.h		config.h
controls.cfg		controls.cfg
file_list_nulldc4wii.txt		file_list_nulldc4wii.txt
frameskipping-flycast.md		frameskipping-flycast.md
index.htm		index.htm
ndce.vcproj		ndce.vcproj
ndce.vcxproj		ndce.vcxproj
ndce.vcxproj.filters		ndce.vcxproj.filters
ndce.vcxproj.user		ndce.vcxproj.user
nullDC.cfg		nullDC.cfg
nullDC.cpp		nullDC.cpp
nullDCe.cbp		nullDCe.cbp
nullDCe.sln		nullDCe.sln
os_base.h		os_base.h
sh4_reg_playground.h		sh4_reg_playground.h
stdclass.cpp		stdclass.cpp
stdclass.h		stdclass.h
types.h		types.h
yabause-wii-frameskipping.md		yabause-wii-frameskipping.md
ztest.txt		ztest.txt

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