Emulation isn't the only way. Many gamers have "hard-modded" or "soft-modded" their original Xbox consoles to play ISOs from an internal hard drive.
formats. While a standard ISO may contain the entire contents of a physical disc—including security sectors and padding—the ConsoleMods Wiki explains that xbox rom iso archive
Before searching for an "Xbox ROM ISO archive," you need to understand the terminology. Emulation isn't the only way