JPS6425390A - Semiconductor storage device - Google Patents

Abstract

PURPOSE:To execute the same function as a conventional one with the smaller number of transistors by composing a logic circuit to output only two conditions of an 'L' level and a high impedance condition. CONSTITUTION:A logic circuit 3 is made into a circuit constitution in which an output terminals WO and the inverse of WO go to the 'L' level or the high impedance condition based on a data input signal and a reading-writing signal R/W. Namely, when the reading-writing signal R/W is at the 'L' level in a reading condition, since, at an inverter circuit Inv1, a transistor Q5 is conducted, a transistor Q6 is not conducted and a node N3 goes to be at an 'H' level, at a NOR circuit 9a, a transistor Q12 goes not to be conducted, a transistor Q14 goes to be conducted and a node N4 goes to be at an 'L' level. As a result, a transistor Q31 goes not to be conducted, and an non-inversion output terminal WO goes to be in the high impedance (Hi-Z) condition. Thus, transistors and circuits for outputting the 'H' level to an output can be reduced, and a semiconductor memory having the same function as a conventional example can be obtained with the smaller number of elements.