The SC-205 controller was released in the late '70s as the second-generation development to the SC-105 controller. The SC-205 was only around a few years before being replaced with the SC-110 in the mid '80s. The SC-205 was the first Flash Technology controller to have individual displays of beacons and their statuses, and was also unique in that it was the first controller with diagnostic capabilities. 205-1 and 205-2 beacons that used a SC-205 controller required a 2444 TTB. The modern FTC-121 controller is essentially a digital version of the SC-205 controller with its diagnostic capabilities.