Television tuning system with means to prevent loss of information during power outages

Claim 1

Apparatus for use with a television receiver, said apparatus comprising: a power circuit for converting a mains power supply voltage to a reduced voltage which is applied as a power signal to several components of said television receiver, said power circuit generating said reduced voltage shortly after said mains power supply voltage is applied thereto and maintaining said reduced voltage until shortly after said mains power supply voltage is removed therefrom; a read/write memory for storing information relating to the operating parameters of said television receiver, said memory having data terminals, address terminals, and one or more control terminals for controlling operation of said memory; a control circuit for controlling said operating parameters of said television receiver as a function of said information stored in said memory and as a function of data signals applied thereto, said control circuit changing the values of said information stored in said memory by applying control signals to said data and address terminals of said memory in response to specific data signal applied to said control circuit; first means for generating a disable signal responsive to an interruption of said mains power supply voltage, said disable signal being generated before said reduced voltage is cut off in response to the removal of said mains power supply voltage from said power circuit, said disable signal continuing until after said reduced voltage is again generated by said power circuit in response to the reapplication of said mains power supply voltage to said power circuit; second means responsive to said disable signal for supplying a series of fixed signals to at least one of said data and address terminals of said memory; and third means responsive to said disable signal for applying to at least one of said control terminals of said memory an appropriate signal for preventing said information stored in said memory from being changed during the period in which said disable signal is generated.