Abstract: A frequency counter obtains frequency data by measuring the frequency of an optionally offset broadcast signal tuned by a tuner having a VCO. A microprocessor is used to determine the frequency difference between the optionally offset signal and the previously tuned signal based on the frequency data measured for each signal, and controls the oscillation frequency of the VCO for the tuner based on this frequency difference using a PLL circuit. The frequency is quickly changed to tune in the optionally offset broadcast signal.

Abstract: A non-volatile memory controlling apparatus wherein a controlled circuit can be controlled by using controlling data from a controller within a device and can be externally controlled by using controlling data from an external controller through an external terminal and the above mentioned various controlling data can be memorized in a non-volatile memory, characterized in that said non-volatile memory has an area which can switch a writing permission and writing inhibition and writing into said area of said non-volatile memory will be permitted when in the controlling mode from said external controller but will be inhibited when not in that mode.

Abstract: A power source switch circuit can remember the last state a switch is in when main power is lost. A capacitor or battery is used to place the switch in its original position after the main power is restored.

Abstract: A channel selecting apparatus for television receiving apparatus and the like which memorizes channel data (about whether signals are present or not in respective channels) in a memory circuit connected to an operating circuit preparing channel selecting data. The received frequency is tuned with the broadcast signal input into an antenna terminal and is then confirmed and analyzed. This is used to determine whether the broadcast signal input into the antenna terminal is a TV signal or CATV signal and whether the CATV signal is of an STD, HRC or IRC system and the receiving mode is automatically determined.