What Are ROMs? A Beginner’s Guide to Retro Game ROMs

ROMs, ROMs, ROMs

Finding and using retro game ROMs is one of the first things every new retro handheld owner runs into, and it gets confusing fast.

This guide breaks down what ROMs are, what emulators and BIOS files do, the file types you will run into, where people actually find ROMs, and how ROM hacks work, all from a beginner’s point of view.

What Is a ROM?

A ROM is just a digital file of a game.

Picture a Pokémon Blue cartridge.

If you took that cartridge and turned it into a single file, that file is the ROM. That is all it is.

So when people tell you to “find ROMs” for your retro handheld, they mean you need the games so you can play them on that device.

Here is the part that trips people up: ROMs are not device specific.

If you have a Pokémon Blue ROM, you can use it anywhere.

A Windows PC, a Linux PC, a retro handheld, a microwave if you really wanted to. It does not matter.

One of the most common questions I see is “can I use these ROMs on another device?” and the answer is always yes.

What Is an Emulator?

If a ROM is the game, an emulator is the console.

Picture your Game Boy.

Now imagine turning that whole console into a program and putting it on your retro handheld or PC.

That program is the emulator, and it plays your ROMs.

Instead of carrying around a big Game Boy brick, you have the Game Boy itself running digitally on whatever device you like.

A great example is a program called RetroArch.

It can install a huge range of emulators, from Arcade and Atari all the way up to PlayStation 1 and beyond.

RetroArch calls these emulators “cores.” Just like a real Game Boy needs games, every core needs ROMs to play anything.

RetroArch is not your only option. There are plenty of standalone emulators too:

Common standalone emulators

• RPCS3 for PS3 games
• PCSX2 for PS2 games
• DuckStation for PS1 games
• Dolphin for GameCube and Wii games

What Is a BIOS File?

You load up, play some Game Boy, everything works. You try Super Nintendo, still great.

Then you go to play Final Fantasy VII on PlayStation 1 and nothing loads.

This is where people start cursing my name.

Some systems need one more piece on top of the emulator and the ROM: a BIOS file.

A BIOS file is basically a digital copy of the original system’s software, and it is what the emulator uses to properly emulate that console.

Not every system needs one. It is mostly the disc-based systems:

Systems that usually need a BIOS

• Sony PlayStation 1
• Sony PlayStation 2
• Sega Dreamcast
• Sega Saturn
• Sega CD

Games on these systems will not run without the right BIOS file in the right place.

It is the classic new-user trip-up, and even long-time users forget it sometimes and wonder why their games stopped loading.

If it happens to you, do not panic, you are in good company.

I have a full BIOS video and guide if you want to go deeper right after this.

Quick Recap

Quick recap before we move on:

• ROMs are the games
• Emulators are the device
• BIOS files are the software that runs the games on the device

In most cases you need all three.

ROM File Types and Zipping

ROMs come in different file types depending on the system, and some systems have several to choose from.

PlayStation 1 alone has a bunch: CUE, BIN, CHD, ISO, M3U, PBP, and more. This is where beginners get lost.

Sometimes you can even run a ROM while it is still zipped, so you do not have to unzip it.

That usually does not work for CD-based games like PlayStation 1, though.

Here is the easy rule of thumb:

The simple zip rule

• If it is a CD-based system, it cannot be zipped.
• Everything else, you can usually leave zipped.

Which file type is best for each system is something you pick up over time.

I keep a page dedicated to the best file types for each system, all compatible with most emulators.

Where Do You Find ROMs?

This is the part everyone skips to, so let’s be honest about it.

You have probably asked in a Discord or forum where to find ROMs and been told “Google it” or “we can’t help with that here.”

Frustrating, but the advice is not wrong.

The real concern for most people is safety: viruses, malware, and knowing which sites to trust.

The community’s short answer really is the correct one.

A plain search for “roms” surfaces the well-known Reddit retro communities right at the top, and those communities keep pinned megathreads that point to the sites people consider safe.

For full sets, archive.org is where a lot of people go (just make sure you are logged in, or you can get locked out of downloading).

A couple of honest limitations:

• Switch ROMs are not part of this, and not something I help with.
• Big all-in-one packs are not really what those resources are for.

My advice for beginners: skip the giant sets

Avoid large sets of games when you are starting out.

A giant pile of ROMs from every system causes choice paralysis and confusion.

Some will not work, you will get stressed, and it is a bad way to start.

Begin with one system. Get some Game Boy games working.

Then move to PlayStation 1, get that going, and so on.

And no, nobody is impressed by “10,000 games on my device.”

A handful working well beats a huge pile you never touch.

ROM Hacks

ROM hacks are games that someone, whether one person or a team, made using an existing game as a base.

They usually add new features, levels, or story to create something new. Pokémon ROM hacks are the most famous, with hundreds out there, and PokéCommunity.com is a fantastic resource for them.

There are also hacks for Super Mario World, the Metroid games, and plenty more.

The confusing part is downloading them.

When you grab a ROM hack, let’s use Pokémon Unbound as an example, you do not get a .gba or .zip file.

You get a patch file with an extension like UPS, IPS, BPS, or xdelta.

Here is why.

For legal reasons, ROM hack developers do not include the base game in their downloads.

We all know how Nintendo is.

If developers bundled actual Pokémon games with their hacks, Nintendo would come after everyone.

Instead they give you a patch file to apply to the original game.

How to patch a ROM hack

1. Open the ROM hack’s readme. It tells you exactly which base ROM you need. Unbound asks for the Pokémon Fire Red “Squirrels” base ROM.
2. Get that exact base ROM. Copying the full name from the readme into a search usually points you straight to it.
3. Use an online ROM patching tool. Select the base ROM, then the patch file. Most tools show green when the two match.
4. Apply the patch. You get a finished .gba file that is now Pokémon Unbound.
5. Rename it if you like, move it to your ROMs folder, open your emulator, and play.

Still need help? Refer to my guide on ROM hacks.

Wrapping Up

That is all there is to it from a beginner’s point of view:

• ROMs are the actual games
• Emulators are the device that plays them
• BIOS files are the software some systems need to run

With this guide, plus my BIOS guide and my emulator setup guides, you are set to play just about anything.

FAQ