ROM

From SMWiki

ROM images are computer files containing the data found in the ROM chip of a video game cartridge. A ROM is, in other words, a video game copied into a computer file.

[edit] Emulation

The machine code stored in the ROM is written for another CPU architecture than that of a regular computer, meaning that one needs a program that interprets the ROM's programming. Such a program is called an emulator. Without an emulator, the ROM is useless.