JPS5679351A - Memory device - Google Patents

Abstract

PURPOSE:To make it possible to easily executing security of the memory contents, by constituting the device so that a correct output cannot be obtained without inputting the input conforming with the contents stored in the key address memory and the regulation of the comparator. CONSTITUTION:When the electric power source is closed, the one-shot circuit 1 generates a pulse output, sets the FF3, and also outputs pulses for a given period of time from the one-shot circuit 2. Address inputs A0-An are input during said period, and when a chip selective input CS is input, the comparator 5 compares the key address memory 4 with the inputs A0-An, and if they coincide, a signal 1 is output. This output is stored in the shift register 22. An output of the memory 4 is varied when the inputs A0-An are varied, and when the inputs A0-An are input so that they coincide with the contents of the memory 4, the circuit 5 outputs ''1''. Then if all the outputs of the register 22 become ''1'', the FF3 is reset, the output Q' becomes ''1'', and therefore the contents of the memory 6 designated by the inputs A0-An are output to the output lines D0-Dm through the output buffer.