Cyber-operating system

As recalled by the Eleventh Doctor, very early versions of the Cyber operating system could be seriously scrambled by exposure to things like gold or cleaning fluid. As Mr Clever was still running some of that code, the Doctor was able to use a golden ticket to impair him. (TV: Nightmare in Silver)

On 15 April 2342, the Upgrade Wars kicked off when two factions of Cybermen failed to concur on what operating system was best to use. (PROSE: Time Traveller's Diary)