Sega Saturn Bios Retroarch [portable] -

To access core options: Load core → Main Menu → Quick Menu → Options

Emulators for simpler consoles (e.g., Genesis, SNES) are often high-level emulations (HLE) . They re-implement the BIOS functions from scratch in software. The Saturn, however, is so complex that reverse-engineering its boot process is incredibly difficult. Therefore, most Saturn emulators use low-level emulation (LLE) , which actually executes the original BIOS code. Without the real BIOS file, RetroArch’s Saturn cores cannot boot games. sega saturn bios retroarch

The core is widely considered the "gold standard" for accuracy. To access core options: Load core → Main