Miyoo Mini Plus Setup Guide with Onion OS 2026

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Install Onion OS — the essential first step for the best experience

The Miyoo Mini Plus ships with a basic stock firmware that lacks many features and has a poor UI. Onion OS is the community-built custom firmware that adds a proper game library, scraper, RetroArch, and far more customization. Always install Onion OS before adding ROMs.

1. Download the latest Onion OS release from GitHub (github.com/OnionUI/Onion). Look for the file named Onion-v4.x.x.zip under Releases → Assets. Do not use unofficial mirror sites.
2. Insert your microSD card into a USB card reader on your PC. If it is not already formatted, format it as exFAT (right-click in Windows File Explorer → Format → exFAT).
3. Extract the contents of the Onion zip file. You will see folders like BIOS/, Roms/, Saves/, and a file called .tmp_update/. Copy all of these directly to the root of the microSD (not inside a subfolder).
4. Safely eject the microSD and insert it into the Miyoo Mini Plus. Power on the device.
5. Onion OS will auto-install on first boot. This takes about 30 seconds. The device will reboot into the Onion OS main menu.
6. First-run: Onion asks which apps to install (RetroArch, PPSSPP, etc.) and which systems to show. Select all systems you plan to use.

Onion OS version to install: Always use the latest stable release from the official GitHub page — Onion is actively maintained and newer releases fix bugs. Avoid alpha or pre-release builds.

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Add ROMs to the Miyoo Mini Plus via microSD

Unlike Android handhelds, the Miyoo Mini Plus does not support USB MTP file transfer. The only way to add games is via the microSD card.

1. Power off the Miyoo Mini Plus and remove the microSD card.
2. Insert the card into a USB card reader on your PC.
3. Open the card in File Explorer. You will see a Roms/ folder (created by Onion OS).
4. Inside Roms/, place your ROM files in the correct system subfolder:
   • Roms/GBA/ — Game Boy Advance (.gba)
   • Roms/GBC/ — Game Boy Color (.gbc)
   • Roms/GB/ — Game Boy (.gb)
   • Roms/SNES/ — Super Nintendo (.sfc, .smc)
   • Roms/NES/ — Nintendo (.nes)
   • Roms/MD/ — Sega Genesis/Mega Drive (.md, .bin)
   • Roms/PS/ — PlayStation 1 (.bin+.cue, or .chd)
   • Roms/N64/ — Nintendo 64 (.z64, .n64) — N64 performance is limited on the Miyoo's hardware; not all games run well.
5. Re-insert the microSD into the Miyoo Mini Plus and power on.
6. In Onion OS, go to the system you added games to — your ROMs will appear automatically. If they don't, go to Games → Refresh Roms.

ROM format tip for PS1: Use CHD format (converted using chdman on PC) instead of BIN/CUE pairs. CHD compresses PS1 games by 30–50% and keeps each game as a single file. Multi-disc games can be combined into one CHD. Onion OS / PCSX4All fully supports CHD.

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BIOS file placement for PS1 and GBA

The Miyoo Mini Plus uses RetroArch under Onion OS. BIOS files go in the BIOS/ folder on the microSD root. Dump these from your own hardware.

PlayStation 1:

• Required file: scph1001.bin (US) or scph5501.bin (US, newer) or scph7003.bin (US). PCSX4All (the PS1 emulator under Onion) requires a BIOS to boot games — HLE is not available.
• Place the file in the BIOS/ folder at the root of the microSD. File name must match exactly (lowercase).
• Verify in Onion: open RetroArch → Load Core → PCSX4All → Core Info — the BIOS status should show as found.

Game Boy Advance:

• Optional file: gba_bios.bin (7,341 bytes exactly). Most GBA games boot without a BIOS via HLE, but a real BIOS fixes intro screens and a small number of compatibility issues.
• Place in the BIOS/ folder. The mGBA core used by Onion will auto-detect it.

What the Miyoo Mini Plus cannot emulate: The Allwinner H700 processor is powerful enough for GBA, GBC, GB, NES, SNES, Genesis, PC Engine, Lynx, GG, and PS1 — but struggles with N64 (some games only), and cannot run PS2, PSP, GameCube, or anything more demanding. For those systems, you need a higher-end device like the Retroid Pocket 4 Pro or AYN Odin 2.

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Customize Onion OS — themes, scraper, hotkeys, and settings

Install a theme:

1. Download a theme from the Onion OS community (search "Onion OS themes GitHub" for official community packs).
2. Extract the theme folder to Themes/ on the microSD root.
3. On the device: Apps → ThemeSwitcher → select and apply the theme.

Scrape boxart:

1. Connect the Miyoo Mini Plus to Wi-Fi (if your device has it — the MM+ has Wi-Fi, the original Mini does not).
2. In Onion OS: Apps → Scraper → select your systems and scan. Scraper pulls game artwork from ScreenScraper and displays it in the game library.

In-game hotkeys (default Onion OS):

• Save state: Menu + R1
• Load state: Menu + L1
• Screenshot: Menu + Power
• Fast forward: Menu + R2
• RetroArch menu: Menu (hold 2 seconds)

Change hotkeys: Apps → RetroArch → Settings → Input → Hotkeys.

Sleep / battery save: Onion OS has a sleep mode triggered by a short press of the power button. Long-press power to bring up the shutdown menu. Always shut down properly (don't just remove the battery) to avoid microSD corruption.

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