melonDS

Overview

melonDS is a free emulator for the Nintendo DS. An emulator is a program that imitates a game console, so that a computer can run the games made for it. melonDS aims to copy the DS as faithfully as it can. It runs most of the DS library, and it also has experimental support for the DSi, the DS's successor.

It is made for people who want accurate emulation on Windows, macOS or Linux and are happy to do a little setup. Its main strengths are a very precise copy of the console, a JIT recompiler for speed, an OpenGL renderer that makes 3D graphics sharper, and several ways to arrange the two screens.

Two things to know first. The official site says that Wi-Fi, DSi emulation and GBA slot add-ons are still work in progress. And the project has announced that development is slowed down for now, so do not expect frequent updates.

Key words explained

• ROM: a file that is a copy of a game cartridge. For the DS, it usually ends in .nds. You must make it yourself from a cartridge you own.

• BIOS: a small program built into the console that starts it up and offers basic functions to games. The DS has two, one for each of its two processors (called ARM9 and ARM7).

• Firmware: the software stored in the console's memory chip. It holds the DS home menu, the owner's name and birthday, the language and the touchscreen calibration.

• Dump: to copy a file out of your own console or cartridge onto a computer.

• Renderer: the part of the emulator that draws the 3D graphics. melonDS has a Software renderer (the processor draws) and an OpenGL renderer (the graphics card draws).

• OpenGL: a way for a program to talk to your graphics card.

• Internal resolution: the size at which the 3D graphics are drawn. A higher value gives a sharper picture but needs a more powerful graphics card.

• JIT recompiler: a speed-up technique. The emulator translates the console's instructions into your processor's instructions while the game runs, instead of doing it one by one.

• Frame rate: the number of images shown per second. The DS runs at about 60.

• In-game save: the save the game itself offers, like on the real console. It is stored in a .sav file.

• Save state: a snapshot of the whole emulator at one precise moment, made by the emulator and not by the game. You can go back to it at any time.

• Hotkey: a keyboard or controller shortcut that controls the emulator itself (for example fullscreen or save state) rather than the game.

• Instance: one running melonDS window. You can start several at the same time.

System requirements

The official site gives no real list of requirements (the joke list on its FAQ page is not serious). Its advice is simply to try melonDS and see how it runs on your computer, and to look at another emulator if it is too slow.

• Operating systems: the official download page offers builds for Windows (x64 and ARM64), macOS (universal), Linux (x64 and ARM64), FreeBSD, NetBSD and OpenBSD.

• The Software renderer needs a reasonably fast processor, because the processor does all the drawing. The OpenGL renderer uses the graphics card and supports higher internal resolutions.

• melonDS has no official version for phones. Unofficial ports exist, but the developers do not support them.

• How to check your computer: on Windows, press Windows + R, type dxdiag and press Enter. The System tab shows your processor and memory, and the Display tab shows your graphics card. On macOS, click the Apple menu > About This Mac. On Linux, the commands lscpu and lspci show the same information.

What you need

• The melonDS program, from its official site. It is free.

• Your game files (.nds), dumped from your own cartridges. The official FAQ says to dump cartridges with a DSi or 3DS and copy the files to your computer. Only use games you own.

• Optional but recommended, the BIOS and firmware of a DS: bios9.bin (4 KB), bios7.bin (16 KB) and firmware.bin (128, 256 or 512 KB). They must be dumped from your own console. The official download page has a section of tools for this, and the FAQ explains how to run them. melonDS cannot provide them.

• Only for DSi games: the DSi BIOS files (ARM9 and ARM7, 64 KB each), the DSi firmware (128 KB) and a DSi NAND image (about 240 MB), all dumped from your own DSi.

• A controller if you like, plus a mouse, which stands in for the stylus on the touchscreen.

Why the BIOS and firmware matter: with them, melonDS can start the console like the real thing, with the DS home menu. The official README says that starting from the firmware needs a dump from an original DS or DS Lite. A firmware dumped from a DSi or 3DS is not bootable; it only contains settings, and it works for starting a game directly, which is the common way to play.

Installation

Always download melonDS from its official download page, because copies elsewhere may be altered. The builds are .zip files.

1. Open the official download page and pick the file for your system.

2. Windows: extract the zip (right-click it > Extract All), open the new folder and run melonDS.exe. There is no installer.

3. macOS: extract the zip and move melonDS into your Applications folder. If macOS refuses to open it, go to System Settings > Privacy & Security and choose to open it anyway.

4. Linux: the page offers an AppImage (a single file that runs on most systems; make it executable, then run it) and a build for Ubuntu.

5. Start melonDS. If a window with the two DS screens appears, the installation worked.

First setup

Every setting lives in the Config menu. Nothing is required to play if you start games directly, but the following steps give the best result.

1. Open Config > Emu settings and go to the DS-mode tab. This is where you give melonDS the paths to bios9.bin, bios7.bin and firmware.bin, if you dumped them from your own console. Use the browse button next to each field.

2. In the same window, the option Boot game directly skips the DS home menu and starts the game at once. The official FAQ says to keep it enabled if your firmware comes from a DSi or a 3DS.

3. Open Config > Input and hotkeys. Click a button in the list, then press the key or controller button you want. Escape cancels and keeps the old value.

4. Open a game with File > Open ROM and choose your .nds file.

5. How to know it worked: the game starts and both screens show the picture. If the window stays black, see Common problems.

Adding your games

melonDS has no game library. You open each file yourself with File > Open ROM. Keep your games in one folder so they are easy to find. If you want the DS home menu (with PictoChat and Download Play), start melonDS with no game, then choose System > Run; this needs a bootable firmware dump. To unload a game, choose System > Stop.

Controls

Controller mapping means telling the emulator which key or button of your device acts as which DS button. In Config > Input and hotkeys, click a button, then press the key you want. For a controller, Backspace clears the mapping. Since version 0.8.1, keyboard keys can also use modifiers such as Ctrl.

• Touchscreen: click on the lower screen with the mouse, like using the stylus.

• The same window has a tab for hotkeys. They work the same way, and control the emulator: fullscreen, closing the lid of the console, playing a microphone sample, and so on.

• Microphone: in Config > Audio settings, the microphone input can be None, your computer's microphone, white noise (works for many games, triggered by the mic hotkey) or a small WAV file.

Graphics and performance settings

Open these under the Config menu (Video settings and Display settings).

• 3D renderer: Software is the most accurate but heavy on the processor. OpenGL uses the graphics card, can be faster, is slightly less accurate and allows a higher internal resolution. Start with OpenGL if your graphics card is not very old. Switch to Software if you see graphical glitches.

• Internal resolution (OpenGL only): how sharp the 3D is. 1x is the original. Higher values look smoother but need a more powerful graphics card and may cause glitches in some games. Raise it step by step until the game starts to slow down.

• Screen layout: Natural stacks the screens like a real DS. Other choices put them side by side or on top of each other. Pick what suits your monitor.

• Screen sizing: decides how the window space is shared between the two screens. Auto chooses a mode depending on how the game uses the screens.

• Screen rotation: turns the screens, to simulate holding the DS sideways.

• Screen size: whole-number window scaling from 1x to 4x.

• Screen filtering: a smoothing filter when the picture is enlarged. Turn it off for crisp pixels.

• Limit framerate: caps the emulation at about 60 frames per second so the game runs at normal speed. Turning it off makes the game run as fast as the computer allows, which is useful only for testing.

• Threaded (Software renderer): lets the drawing use a second processor core.

Note: the official site lists a JIT recompiler among the features. It is set in the emulation settings. Keep it on if the option is there, since it makes the emulator much faster.

Saves

There are two kinds of saves, and it helps to know the difference.

• In-game save: the normal saving the game offers. melonDS writes it to a raw .sav file. It is the equivalent of the memory in the real cartridge.

• Save state: a snapshot made by the emulator. With the default keys, Shift + F1 to F8 save into slots 1 to 8, and F1 to F8 load them. Shift + F9 saves under a name you choose and F9 loads any state file. F12 undoes an accidental load. Slot states are stored next to the game file.

• In Config > Savestate settings, the option for separate savefiles keeps your in-game save safe when you load a state.

• Importing a save from another emulator: melonDS detects the type of save from the file size, so it must be exact. Since version 0.9.1, an Import savefile function converts saves from DeSmuME, DraStic or a flashcart.

• Backup: copy the .sav files and the save state files to another folder or drive from time to time.

Local multiplayer and Wi-Fi

Wi-Fi is still a work in progress, so not all games work. Two melonDS windows on one computer can connect to each other. The timing is strict, so it can be unstable; the FAQ says that turning off the frame rate limit may help. More than two windows will probably not work.

Online play uses an emulated access point called melonAP. Direct mode is the most reliable but needs libpcap (or WinPcap), a wired network connection and administrator rights. Indirect mode is the easiest to set up. These options are in Config > Wi-Fi settings.

Updating

Download the new version from the official page and extract it to a new folder. Your games and saves are not inside the program folder, so they stay. Use stable releases. The site warns that nightly builds can fix bugs but may be unstable.

Common problems

• A game does not start, or the screen stays black: the file may be damaged or not a real .nds file. Test another game. If only some games fail, add the BIOS and firmware dumped from your own DS.

• The window shows the DS home menu but cannot start games with System > Run: you need a bootable firmware, from an original DS or DS Lite. Use File > Open ROM with Boot game directly instead.

• The game runs slowly: make sure the JIT recompiler is on, lower the internal resolution, or switch to the OpenGL renderer.

• Graphics look wrong with OpenGL: lower the internal resolution or switch to the Software renderer.

• The picture is blurry: switch to the OpenGL renderer and raise the internal resolution, and turn off screen filtering.

• My save from another emulator is not found: use the Import savefile function. The save must have the exact size melonDS expects.

• Multiplayer does not connect: Wi-Fi is not finished. Try with two windows only and turn off the frame rate limit. Some games do not work.

• No sound in a game that asks you to blow: set a microphone source in Config > Audio settings.

Going further

• melonDS official site and its Howto and FAQ.

• Official forum.

• Source code and bug tracker on GitHub.

• melonDS Android on phones (not an official melonDS project).

• RetroArch with a melonDS core.