emux (SMS)

emux (SMS) emulates Sega Master System. It reads 1 file, 1 of them required: without a required file it does not start games.

About this profile

Detail	Value
Type	libretro
Classification	Official port
Source	https://github.com/libretro/emux
Upstream	https://github.com/sronsse/emux
Version	0.1, stated in configure.ac
Revision	libretro/emux@3e558cb15157
Profiled	2026-03-23
Profile	YAML, JSON
Cores	emux_sms
Systems	Sega Master System

Install this emulator's files

The installer finds your setup and its BIOS folder, then downloads only the files this emulator reads there and checks each one.

Windows

Open the Start menu. Type PowerShell and open it. Paste the line. Press Enter.

PowerShell

&([scriptblock]::Create((irm https://abdess.github.io/retrobios/i.ps1))) --emulator emux_sms

macOS

Open Terminal, in Applications, then Utilities. Paste the line. Press Return.

Terminal

curl -fsSL https://abdess.github.io/retrobios/i | sh -s -- --emulator emux_sms

Linux

Open a terminal. Paste the line. Press Enter.

Terminal

curl -fsSL https://abdess.github.io/retrobios/i | sh -s -- --emulator emux_sms

Steam Deck

Switch to Desktop Mode. Open Konsole. Paste with Ctrl+Shift+V. Press Enter.

Terminal

curl -fsSL https://abdess.github.io/retrobios/i | sh -s -- --emulator emux_sms

Android (Termux)

Install Termux, a terminal app. Run pkg install python and termux-setup-storage once. Then paste the line. Press Enter.

Terminal

curl -fsSL https://abdess.github.io/retrobios/i | sh -s -- --emulator emux_sms

On the device

Open a terminal on the device. Or connect from a computer with SSH, a terminal over the network. Paste the line. Press Enter.

Terminal

curl -fsSL https://abdess.github.io/retrobios/i | sh -s -- --emulator emux_sms

Technical notes

emux is a multi-system emulator by Sebastien Ronsse. BIOS and cartridge code identical between upstream and libretro fork (only difference: libretro adds g_ram_data/g_ram_size exposure in mach/sms.c for RETRO_MEMORY_SYSTEM_RAM).

BIOS loaded via file_map(PATH_SYSTEM, "bios.sms", 0, BIOS_SIZE) in sms_mapper_init (controllers/mapper/sms_mapper.c:162-165). Returns false on failure, no HLE fallback. Mapped at 0x0000, overlays cartridge ROM until bios_disable bit set in slot control register (controllers/mapper/sms_mapper.c:79-82).

No hash validation. Code accepts any file >= 8192 bytes. is_experimental=true. No save states, rewind, or netplay.

Files

1 file: 1 required, 0 optional.

In this collection: 1 in repo and 0 missing.

Required

bios.sms required in repo

Sega Master System BIOS

• System: Sega Master System
• Mapped at 0x0000, overlays cartridge ROM until bios_disable bit set. file_map rejects files < 8192 bytes (main/file.c:59).

• Size: 8.0 KB
• Collection copy: bios/Other/zesarux/sms.rom
• Platforms: bios.sms and bios_E.sms and bios_U.sms: Lakka, RetroArch, RetroPie. bios/bios_E.sms and bios/bios_U.sms: AmberELEC, EmuELEC. SMS_us_1.3.sms: BizHawk. [BIOS] Sega Master System (USA, Europe) (v1.3).sms: RetroBat. bios.sms: ROCKNIX. bios/bios.sms: RetroDECK. mastersystem/bios_E.sms and mastersystem/bios_U.sms: Recalbox. sms/bios.sms and sms/bios_E.sms and sms/bios_U.sms: RomM

Validation and source

• Validation: size
• Asked for by: emulator code, libretro port
• Source: controllers/mapper/sms_mapper.c:12 (emulator code, libretro port), controllers/mapper/sms_mapper.c:61 (emulator code, libretro port), controllers/mapper/sms_mapper.c:162-170 (emulator code, libretro port)

Next steps

• Get your files, for the setup you play on
• Every system, and the files each one needs
• When a game does not start

Data as of 4 November 2026.