NitroSwan DS

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Revision as of 05:26, 10 February 2022 by HydeWing (talk | contribs)
NitroSwan DS
AuthorFredrik Ahlström (FluBBa)
Last Updated2022/02/10

This is a Bandai WonderSwan (Color/Crystal) & PocketChallenge V2 emulator for the Nintendo DS.


Create a folder named nitroswan in either the root of your flash card or in the data folder. This is where the settings and save files are stored.

Next put your games and bios files into a folder (stub version for the bootrom will be used if that is not found).

Depending on your flashcart you might have to DLDI patch the emulator.

The save files should be compatible with most other WonderSwan emulators.

User guide



  • Load Game - Select a game to load.
  • Load State - Load a previously saved state of the currently running game.
  • Save State - Save a state of the currently running game.
  • Load NVRAM - Load non volatile ram (EEPROM/SRAM) for the currently game.
  • Save NVRAM - Save non volatile ram (EEPROM/SRAM) for the currently game.
  • Save Settings - Save the current settings (and internal EEPROM).
  • Reset Game - Reset the currently running game.



  • Autofire - Select if you want autofire.
  • Controller - 2P start a 2 player game.
  • Swap A/B - Swap which NDS button is mapped to which WS button.


  • Mono Palette - Here you can select the palette for B & W games.
  • Gamma - Lets you change the gamma (""brightness"").
  • Disable Foreground - Turn on/off foreground rendering.
  • Disable Background - Turn on/off background rendering.
  • Disable Sprites - Turn on/off sprite rendering.

Machine Settings:

  • Machine - Select the emulated machine.
  • Select WS Bios - Load a real WS Bios.
  • Select WS Color Bios - Load a real WS Color Bios.
  • Select WS Crystal Bios - Load a real WS Crystal Bios.
  • Import internal EEPROM - Load a special internal EEPROM.
  • Clear internal EEPROM - Reset internal EEPROM.
  • Cpu speed hacks - Allow speed hacks.
  • Change Battery - Change to a new main battery (AA/LR6).
  • Language - Japanese and English.


  • Speed - Switch between speed modes.
    • Normal - Game runs at it's normal speed.
    • 200% - Game runs at double speed.
    • Max - Games can run up to 4 times normal speed (might change).
    • 50% - Game runs at half speed.
  • Autoload State - Toggle Savestate autoloading. Automagically load the savestate associated with the current game.
  • Autoload NVRAM - Toggle EEPROM/SRAM autoloading. Automagically load the EEPROM/SRAM associated with the current game.
  • Autosave Settings - This will save settings when leaving menu if any changes are made.
  • Autopause Game - Toggle if the game should pause when opening the menu.
  • Powersave 2nd Screen - If graphics/light should be turned off for the GUI screen when menu is not active.
  • Emulator on Bottom - Select if top or bottom screen should be used for emulator, when menu is active emulator screen is allways on top.
  • Debug Output - Show an FPS meter for now.
  • Autosleep - Doesn't work.


L+R or Touchscreen - Open menu

Hold Start when starting a game - Enter boot rom settings (internal EEPROM is saved when saving settings)


D-Pad or Touchscreen - Navigate menu

A or Double tap - Select an option

B or Touchscreen - Go back a step

L/R - Select between the tabs


NitroSwan (WonderSwan) | Nintendo DS | Games Showcase (Stranno)

Known issues

Savestates does not work yet.


v0.3.0 2022/02/10

  • Added banked SRAM emulation.
  • Fixed zip decompression buffer size.
  • Optimized cycle counting.
  • Optimized Program Counter.
  • Optimized memory access.
  • Optimized opcodes.

v0.2.0 2022/01/20

  • Completed the rewrite of the cpu core in ARM asm.

V0.1.3 2022/01/09

  • Rewrote parts of the cpu core in asm.

V0.1.2 2021/12/18

  • Backgrounds works.
  • Sprites works.
  • Mono mode works.
  • Fixed Interrupts and Timers.
  • Added EEPROM emulation.
  • Added loading of bootrom for both WS & WSC.
  • Added loading/saving of sram/eeprom.
  • Added sound.
  • Fixed interrupt routine in CPU.

V0.1.1 2021/10/17

  • Started port to Nintendo DS & devkitPro.

V0.1.0 2006/07/28

  • Initial release.

V0.0.0 2006/07/23

  • Started Coding.


Huge thanks to Loopy for the incredible PocketNES.

Thanks to:

  • Flavor & Koyote for WonderSwan info.
  • Godzil for the boot rom stubs.
  • Dwedit for help and inspiration with a lot of things.

External links