Why do some emulators need Bios files?

[Unknown]

I can’t help but wonder why a system like intelevison needs bios files to be emulated but the NES doesn’t. What do bios files do in emulators anyway? Why do emulators that make Bios file optional sometimes preform better with them? This is all out of curiosity. I’m not having problems with retropie right now.

[dankcushions]

@unknown the BIOS is the internal rom (storage) of the console that contains essentially the operating system of the console. some consoles don't have one, or have one that is so simple that emulators can entirely mimic it.

others you have to dump (download) the BIOS from the console, and provide it for the emulator so it run the console, allowing you run games.

some emulators (eg lr-pcsx_rearmed) have an emulated BIOS for the emulator to fall back on if there's no BIOS field supplied, but they're not feature-complete there will be some/many compatibility issues. interestingly for lr-pcsx_rearmed, the emulated BIOS is currently receiving a load of fixes, so it might work better than before (but i would still use a BIOS file for best results)

[Unknown]

@dankcushions So you are saying that they contain data that sets the rules for how the games should run.

[Clyde]

@unknown As @dankcushions said, they are the operating system of the console. So essentially, they fulfill the same role as Windows or Linux do for PC, or MacOS does for the Mac.

Early home computers like the Commodore 64 also had their operating systems in their hardware roms instead of installable software like todays computers do.

[Unknown]

@clyde thanks now I understand.