Re-Initialize EEPROM (Factory Restore)

1. Press DISK.
2. Select DISK UTILITIES.
3. Select COPY SYSTEM.
4. Use the cursor controls to highlight the internal system source.
5. Press STORE (or execute command) to copy system ROM back to EEPROM, re-initializing memory.

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