F1 89 Button is the Ejector Seat ok ok its the Button for Pit Commuincations or it could be the Pit Limiter Button , can't be much else , there again I can't remeber the Regulations for 1989 let alone 2011
There were no pit speed limits until 1994, so it wouldn't have been a limiter button. Its most likely the radio. In the 80s, most of the instruments were located in the cockpit around the driver as levers and knobs. As a radio only needs to be on or off, it only needs a button.