Printed circuit board having conductors which can be decoupled for isolating inactive integrated circuits connected thereto

摘要

A communication system is presented whereby sequences of video screens sent from a host CPU to a video controller can be stored and subsequently retrieved by a terminal located remote from the host CPU. Detection logic, controller memory, processor and a communication unit are compiled as a system configured upon a PCB. The PCB is configured to maintain certain vital functions even if power supplied from an expansion bus ceases. The PCB may employ a battery which maintains processor and controller memory activities and communication therebetween for a period of time sufficient to sustain video screen information stored within the controller memory. Thus, decoupling circuitry is present which prevents drain upon the battery if the communication unit is not being used. The decoupling unit separates power and signal conductors between portions of the printed circuit board. A power status signal is indicative of the voltage level within power conductors of one portion relative to a voltage level within power conductors of another portion to effectuate decoupling therebetween.