emux (NES) - RetroBIOS

Type	libretro
Source	https://github.com/libretro/emux
Version	0.1
Profiled	2026-03-19
Cores	emux_nes
Systems	nes

No BIOS or firmware files required. This core is self-contained.

emux is a multi-system emulator by Sebastien Ronsse, supporting CHIP-8, Game Boy, NES, and Sega Master System as separate libretro cores.

NOT an alias of FCEUmm. Completely different codebase. The NES core does not require any BIOS or firmware files. The .info declares no firmware_count.

The NES has no boot ROM. CPU starts at the reset vector address stored at 0xFFFC-0xFFFD (cpu/rp2a03.c RESET_VECTOR).

Cartridge loading in controllers/mapper/nes_mapper.c: - iNES header parsed (magic 0x1A53454E) - Mapper number extracted from flags6/flags7 - Supported mappers: NROM (0), MMC1 (1), MMC3 (4) - PRG-ROM and CHR-ROM mapped via file_map(PATH_DATA, ...)

Memory map from mach/nes.c: CPU bus: 0x0000-0x07FF WRAM (2 KB, mirrored to 0x1FFF) 0x2000-0x2007 PPU registers (mirrored to 0x3FFF) 0x4000-0x4013 APU registers 0x4014 Sprite DMA 0x4016-0x4017 Controller ports 0x6000-0x7FFF SRAM 0x8000-0xFFFF PRG-ROM

PPU bus: 0x0000-0x1FFF CHR-ROM/RAM (pattern tables) 0x2000-0x2FFF VRAM (nametables, 4 KB) 0x3F00-0x3F1F Palette RAM

system_directory obtained via RETRO_ENVIRONMENT_GET_SYSTEM_DIRECTORY (libretro/libretro.c:23-25) but not used for any file loading.

is_experimental=true. No save states, rewind, or netplay support. Supported extensions: nes, bin, rom.

Generated on 2026-03-20T19:12:20Z