Method and apparatus for controlled removal and insertion of circuit modules

Abstract From the Canadian patent

An electronic circuit board electrically connected to other circuits of a data processing system by means of a bus, may be removed and re-inserted in the system without the necessity of disabling other circuits connected to the bus. A latch actuated switch provides a control signal in anticipation of circuit board removal. The control signal activates a finite state machine which seizes control of the bus after completion of any current bus communications and stops the generation of clock pulses normally required in bus communications. This prevents other circuits from accessing a bus and also prevents extraneous pulses which may occur on the bus during removal of the circuit pack from …