The MK.IV Fire Control System, also known as the MK.IV FCS was a type of targeting computer.
A sophisticated fire control system, the Mk.IV links together all the weapons on a ship, including fixed weaponry and turrets, allowing the pilot to fire them all with a single pull of the trigger. Due to the system's sophistication, the pilot could ultimately focus on flying; the fire control system doing the vast majority of the heavy lifting by managing the targeting of individual weapons. Able to be activated and deactivated with a flip of a button, the system's versatility and ease of use was countered by a severe weakness; because all weapon control systems were routed through the FCS, if the ship was hit with an ion cannon while the system was activated, then all weaponry would simultaneously be crippled.
The MK.IV was commonly used by bounty hunters, and was notably installed stock on the Lancer-class pursuit craft.