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Super Nintendo MSU-1

Super Disc System (MSU1) icon Super Disc System (MSU1) logo

Overview

MSU-1 is the fan-made Super Nintendo enhancement that streams CD-quality PCM audio, CDDA music and large data files while keeping the original cartridge logic. REG-Linux keeps these ROMs under a separate snes-msu1 system so they appear with their own artwork and metadata while still running via SNES-capable cores.

Technical specifications

  • Manufacturer: Nintendo
  • Release year: 1991
  • Hardware type: console
  • EmulationStation group: snes

Quick reference

  • ROM folder: /userdata/roms/snes-msu1
  • Accepted formats: .smc, .sfc, .zip, .7z, .squashfs
  • Emulators: libretro: bsnes, libretro: bsnes_hd, libretro: snes9x, libretro: snes9x_next, libretro: pocketsnes
  • System group: snes-msu1, optional snes

ROMs & assets

Each MSU-1 patch bundles the base SNES ROM (.smc/.sfc) plus an MSU-1 folder containing track-by-track PCM audio, optional streaming data and the .msu header file describing the streams. Store the ROM and its MSU data under /userdata/roms/snes-msu1/<Title>/, keeping the audio files inside MSU-1 or similar subfolders referenced by the header. Zip or SquashFS archives are acceptable as long as they only contain the ROM and its MSU directory; avoid extra subdirectories.

When the ROM loads, the core reads the header and automatically binds the audio tracks to the emulated CD bus.

Emulators

RetroArch / bsnes / snes9x cores

RetroArch exposes MSU-1–capable cores (bsnes, bsnes_hd, snes9x, snes9x_next, pocketsnes). Open the Quick Menu ([HOTKEY] + south face button) to toggle the standard SNES options (snes.videomode, snes.ratio, snes.shaders, snes.gfxbackend, snes.audio_latency, snes.video_threaded). Use per-game overrides to lock in settings such as:

  • snes.dual_cpu_mode/snes.cpu_clock (bsnes) for speed ceilings.
  • snes.nine_slot_offset or custom MC features for patch compatibility.

Enabling Fast Boot in the Quick Menu also ensures MSU-1 games load quickly without rerunning the BIOS.

Controls

The SNES overlay at ../images/controller-overlays/snes-1.png reflects the DualShock-style layout required by most MSU-1 hacks. Bind any extra hotkeys (e.g., cycle tracks, reset) via /remapping_controls_per_emulator.

Troubleshooting

  • Verify each MSU header specifies track filenames that exist inside the MSU folder.
  • Use bsnes or snes9x because some lightweight ports drop MSU-1 support.
  • Keep MSU ROMs separate from standard SNES images so overrides and cheats stay tidy.
  • For general RetroArch help see the generic support pages.