There are two ways developers handle this. The first is High-Level Emulation (HLE), where the emulator developer writes their own code to simulate what the BIOS does, bypassing the need for the original file. This is common for older systems like the Nintendo 64 or Sega Genesis, where the boot process is relatively simple. Eng Ntr Lovely | Students V111 V250209 Hot
When a console manufacturer builds a system, they write specific code that dictates how that machine behaves. For example, the original PlayStation's BIOS contains the code for the memory card manager and the CD player interface. Without this code, the PlayStation hardware would be a lifeless box of chips and plastic. Baby Play Comic | Work
Despite their technical necessity, EmuELEC BIOS packs exist in a murky legal zone. The files contained within these packs are intellectual property owned by the console manufacturers (Sony, Nintendo, Sega, etc.).