Whiteboard
Whiteboards became commercially available in the early 1960s, but did not become widely used until 30 years later. Early whiteboards needed to be wiped with a damp cloth and markers had a tendency to leave marks behind, even after erasing the board. Dry-erase markers for whiteboards were invented in 1975.
Spectrum (arena)
The Spectrum, along with the Met Center and The Forum, was one of the first sports arenas to have a scoreboard with a messageboard. Furthermore, the messageboards on the Spectrum scoreboard were the first dot matrix screens in pro hockey or basketball, capable of photos, animation, and replays as well as messages. This was replaced in 1986 with ArenaVision, which consisted of six 9-by-12-foot rear-projection videoscreens at the top and a four-sided American Sign and Indicator scoreboard at the bottom. Inside the videoscreens were General Electric projectors located 15 feet away from each screen.