Each zip file contains every file needed for that game to run independently. This is the easiest for beginners but uses the most storage space.
When you download a ROM for a console emulator, it is often a single file (e.g., SuperMarioWorld.sfc ). However, arcade games are different. An arcade board often contained multiple chips: one for the main program, one for graphics, one for sound, and sometimes encryption keys or bios files. Mame Roms Pack Zip
For legal and complete archives, several high-quality sources provide full sets or curated collections: Internet Archive Each zip file contains every file needed for