The current version of installed Operating Firmware (Code Version) can be found by selecting the “About” screen in the Menu. 

DB4:  Menu > About
DB2:  Menu > Advanced > About

This screen will also display the 24 digit eID number which is unique for your mixer.

We would advise keeping a note of this number and the unit's serial number in a safe place.
The serial number is found on a sticker below the on / off button on the back of the unit.
The serial number sticker can be easily removed, changing the eID number is much trickier!