Updating Operating System (Firmware)

1. Obtain the update file/disk.
2. Go to the Disk Menu.
3. Select "Disk Utilities".
4. Select "Copy System" and point to the drive containing the new OS.
5. Alternatively, use the "Software Update" or "Re-initialize EEPROM" utility mentioned in the Disk Utilities section.

Source: E64 — e-mu-eos-4-0-manual (manual)