A ROM is a computer file that contains a copy of data from read-only memory (ROM). It may be a firmware or a game cartridge, for example. Previously, video games were stored on cartridges. There are some cartridges that have just one game while others have several. ROM files are usually in a specific format that is appropriate for an emulator. They must be downloaded on your device. However, ROM files have certain extensions. Only a certain emulator can open them. Because of their popularity, game consoles from the 1980s became extremely popular.