While the M model was being worked on, the US Navy also introduced an upgrade for the Mark 91 fire control system, the "Mark 23 Target Acquisition System" (TAS). TAS included a medium-range 2D radar and IFF system that fed information to a new console in the ship's combat information center. The Mark 23 automatically detected, prioritized and displayed potential targets, greatly improving reaction times of the system as a whole. The Mark 23 is also used to select targets for most other weapons systems, including gunfire and other missile systems. TAS started entering the fleet in 1980.