(coexisting on another dimensional plane)
A security board was a device that detected abnormal increases in power utilized on a starship.
In 2267 in the mirror universe, Hikaru Sulu's security board alerted him to the fact that the ISS Enterprise's computers were being used extensively. Later, Nyota Uhura distracted him so that he wouldn't notice Scotty's diversion of power to the transporter. (TOS: "Mirror, Mirror")