You might find the same game available in three different formats. While they all contain the same core game data, the way that data is ordered (its "endianness") varies:
Most modern emulators like Project64 or Mupen64Plus can automatically detect and read all three formats. However, keeping your library in .z64 is recommended for the best long-term compatibility. Best Emulators for Z64 ROMs z64 rom
The primary historical context for the term "Z64" lies in the hardware peripherals developed during the Nintendo 64's lifespan. Devices like the Z64 and its contemporaries, such as the Doctor V64, were aftermarket attachments that connected to the Nintendo 64 console. Functioning as disk drive emulators, these devices allowed users to back up their game cartridges onto zip disks or, conversely, load game images (ROMs) onto the console. At the time, these devices occupied a legal gray area. While manufacturers marketed them as tools for backing up legally owned software—a right generally protected by fair use principles—game publishers viewed them as facilitators of rampant piracy. The Z64 hardware represented a technical workaround for the console's limitations, allowing gamers to bypass the expensive cartridge format, but it also laid the groundwork for modern digital preservation efforts. You might find the same game available in