APPARATUS FOR RECORDING A CALL NUMBER IN THE CARDPHONE

摘要

The device is fabricated that a timer is connected to a switch and the output signal of the timer is applied to the clock and clear stages of a counter; the clear stage is connected to a switch; a button recognition signal of a tone receiver is connected to one side of an OR gate, and at the same time, to the write enable stage of a SRAM and connector; the output signal of the counter is connected to the connector and the address line of the SRAM; the output signal of an AND gate connected to the output of the counter is applied to the other side of the OR gate; the output signal of the tone receiver is transmitted to the data bus of the SRAM and connector; the SRAM is chip-selected according to the operation of the switch; the output voltage of a battery backup circuit is applied to the SRAM.