To run Nintendo 3DS Emulator, you will need a BIOS file. You can download it along with the latest version of the emulator program here. Without it, you won’t be able to run the program at all! When you run 3D Emulator Pro, you will be prompted to locate the BIOS file. Simply select the BIOS you downloaded once and you won’t be asked again.
What is a BIOS exactly? BIOS is an acronym for ‘Basic Input/Output System and you can regard it as a firmware. What it actually does it that it checks for various requirements that are needed to run the hardware, as well as running the operating system for it. In Nintendo 3DS game console, the BIOS is a combination of a physical chip and firmware software that is located inside. 3DS Emulator BIOS emulates all this via software instructions.
After you download the emulator and have it extracted, the BIOS will be located in the /BIOS folder.