There were two basic types of space weaponry: energy and conventional. Energy weapons began with microwave lasers for offense and were typically secondary to conventional, physical weapons. From 4000 BBY however, energy weapons were the dominant form of weaponry in space combat, dominated by the turbolaser and the laser cannon, outgrowths of blaster technology that had matured at the same time. On capital ships, energy weapons were normally grouped into batteries based upon the weapon type and its placement upon the hull. For example, on an Imperial-class Star Destroyer the heavy turbolasers on the portside of the hull's dorsal surface would be grouped into one battery, while those on the starboard dorsal surface would be grouped into a second battery. Targeting computers in capital ships