BIOS files for emulation – What, Why and Where

If you’ve been setting up any sort of retro console emulation, especially for the PlayStation and GameBoy devices, you’ve probably have come across the need for BIOS files. It can be a bit confusing about what these are, why and if you need them, and which and where to get them.

So in this video I’ll walk you through the basics so you can get your emulators ready to play all the games.

What Are BIOS Files?

When any computer system starts up it needs program code to make it work. Without this it will just sit there and do nothing.

We tend to divide this code up into two main sections. Software and firmware. It’s all just the same in terms of the instructions used, but when the code runs and what it does makes this difference.

When a microprocessor is powered on, it usually looks at a certain block of memory to find a reset vector. This tells it at which memory address it should start executing code. The processor jumps to that memory location and just starts running whatever it finds. At this point it’s just running all by itself with no connections to the devices around it. To be able to put pixels on the screen, read the game controller or anything else it needs some really low level code that knows which electrical signals need to be sent to the various devices to make them work. This is at a very basic level where we build code to allow the processor to control the inputs and outputs that connect the computer or games system together.

This code forms our Basic Input Output System, or BIOS.

Because the BIOS is very closely linked to the actual hardware devices it sort of forms part of the hardware but is of course code and therefore software. So that’s where we get the idea of firmware. Software that’s integral to the hardware.

Once we have a BIOS, our game code doesn’t have to worry about which pin on the processor needs to be turned on and off to send data to the video decoder to make a red pixel appear on the screen. It can just ask the BIOS to do it.

So the BIOS files we need for our emulators are just the base layer of code that the game system we want to emulate uses.

On some consoles this code can be legally supplied with the emulator, or the emulator developers have rewritten it to create their own, fully compatible version. On other systems the manufacturer still enforces their copyright on the BIOS code so the emulator creators can’t legally supply it to us. This is where we need to find our own copies of the original BIOS code to allow the emulator to work.

Which System Need BIOS Files

So now we know what a BIOS is and why it might be missing from an emulator how do we know if we need one or not?

Luckily the emulator developers publish this information and some dedicated enthusiasts assemble this information and publish it on the web. If you head over to the gametechwiki.com website you’ll find all this information collected together..

Here you can browse through pretty much every system and find what files are needed for each emulator. In the notes section you’ll find details to show you which files are needed, which are optional and any special cases. You’ll also find the links in the File Types column are well worth checking out.

If you don’t want to work through the list you can just try playing some games. If you need a BIOS most emulators will tell you or give you the option to use a less compatible copyright free version.

Installing All the BIOS Files

The final option for BIOS is to simply install everything in one go to make sure you’ve covered all the permutations.

Most of use will end up using something like RetroArch as the main emulation system. As this is so common people have built full BIOS packs that simply slot into the multi emulator with every file in the correct place with the correct file name.

As usual you’ll need to find these BIOS packs yourself but a simple Google search will bring them up quite easily. Indeed there is a Multi System section in the gametechwiki page that might be of interest.

Here I have a RetroArch BIOS pack.

As you can see there are a number of folders which contain all the files needed to get all the emulators up and running. All you have to do is copy these to the RetroArch installation folder and it will automatically drop the right files in the right place.

For example there will be a system folder in the RetroArch installation folder and if we look inside the BIOS pack system folder you’ll see all the BIOS files waiting for you.

This route is also a great way to get the files you need for individual emulators. Everything is in there. So you just ned to pick out the files you need and drop them into the emulator of your choice.

What Next?

Well that’s about it for BIOS files. You can of course go a lot deeper into the subject. Not all BIOS versions are created equal. You may well find that a few particular games or emulators need a specific version, or hacked version to allow them to run, or one BIOS file might give better performance than another. But again, these are edge cases and if you are playing around in those areas you’ll probably know what you are doing.

For the most of us getting a compatible file to let the game run will do just fine.

So I hope you’ve found this video useful. Please do click that like button and don’t forget to subscribe to the channel for more gaming, modding, coding, electronics and making projects.