A newer, more advanced compression format used with the Cerbios BIOS. It maintains the original disc structure while "zeroing out" padding for maximum space savings.

Traditional Xbox ISOs are "one-to-one" rips that include massive amounts of or "padding" used originally to deter piracy. "Highly compressed" ROMs typically fall into three categories:

A repackaged format that removes the security padding and system update folders. These are often significantly smaller and are the standard for emulators like Xemu .

A classic utility that automates the process of converting and transferring XISO games to a modded Xbox via FTP.