A CPU is a type of Gear equipment. It is a computer system which provides additional stat bonuses to the player's Gear. CPUs tend to emphasise attack bonuses, but may provide other stat bonuses as well, such as defence, evasion, or fuel bonuses.
A Gear is not required to be equipped with a CPU in order to take off, but they are very useful nevertheless.
Special types of CPUs can also be created at the Factory.