Patent ID: 7058170

Claim:
An apparatus for supporting a first system control circuit card and a second system control circuit card capable of providing substantially identical functions as said first system control circuit card, on a common backplane of a microprocessor-based telecommunications switching system containing a plurality of circuit boards, said apparatus comprising: a system control panel; first signaling means capable of conveying a first OK status signal indicative of said first system control circuit card's operational status to said system control panel; second signaling means capable of conveying a second OK status signal indicative of said second system control circuit card's operational status to said system control panel; arbitration means capable of comparing said first OK status signal and said second OK status signal and producing a resultant signal, said arbitration means being supplied with a plurality of clock signals and power sources; and, switching means capable of using said resultant signal to cause said telecommunications switching system to select to use one of said first system control circuit card and a second system control circuit card; wherein said arbitration means feeds said resultant signal output from said arbitration means back as an input to said arbitration means in order to determine which of said first system control circuit card and said second system control card is a current system controller and ensure that when said first OK status signal and said second OK status signal are either both true or both false, said current system controller remains as said current system controller.