The Mark IV bridge simulator was a mock-up of the refitted bridge of a Constitution-class starship for use by Starfleet cadets in Starfleet Academy training missions, such as the Kobayashi Maru scenario.
The simulator was rigged with pyrotechnics in order to realistically simulate battle conditions. As a result of the pyrotechnics, the simulator frequently required maintenance. Smoking was prohibited in the simulator.
Captain Spock had a class of cadets, under the command of Saavik, make use of the simulator (playing the role of the USS Enterprise) in 2285, joined by Starfleet officers Leonard McCoy, Hikaru Sulu, Uhura, and Montgomery Scott. Admiral James T. Kirk also visited the simulator to watch the cadets' performance on the Kobayashi Maru scenario. (Star Trek II: The Wrath of Khan)