Polymega® features integrated BIOS functionality for CD-based emulators, which provides coverage for the vast majority of games. You can optionally override the internal BIOS for each system by placing alternative BIOS files on the SD Card (or USB Thumb Drive) with the correct naming within a folder called "bios". If these official BIOS files are found, Polymega will automatically use them until the files are removed.
Official BIOS files can be extracted from your original console hardware, assuming you are familiar with the extraction process. We cannot provide access to these files as they are original copyright of the hardware manufacturers. But, if found on the SD card or a USB Thumb Drive, the official BIOS files that will take precedence over Polymega's pre-installed BIOS files are:
Please note that Save States are not compatible between internal and side-loaded official BIOSes, so when you first get your system, you'll want to choose which BIOS you want to use carefully when playing games, and stick with it through the rest of the game.