OS / Firmware Update

1. Load the new OS file into the E4XT (refer to Disk -> Load).
2. Press the MASTER button.
3. Select Utilities.
4. Select Copy System.
5. Select the source drive and file containing the new OS.
6. Confirm to update the Operating System.

Source: E4XT Ultra — e-mu-eos-4-0-manual (manual)