Read only memory device with memory cells each storing one of three states

摘要

A ROM device includes a plurality of memory cells each storing one of three states, a cell voltage generating circuit for providing a cell voltage corresponding to the state stored in a selected one of the memory cells, and a reference cell for providing a reference voltage which is substantially the same as the cell voltage provided by a memory cell storing an intermediate state of the three states. The ROM also includes a comparator circuit for generating a logical output signal based on the result of a comparison between the cell voltage and the reference voltage.