very fast polyhydric festwertspeicheranordnung

摘要

PURPOSE: To obtain a multivalued ROM having high reading speed. ;CONSTITUTION: Threshold value of a memory cell M is set at any one of VT0, VT1, VT2 and VT3. An address decoder 1 selects one word line A based on a part of address signals Xn-X1. The remaining address signal XO is fed to a control circuit 2 which designates to set the voltage of a word line, for which '0' is selected, between VT1 and VT2 and to vary the voltage of a word line, for which '1' is selected, sequentially between VT1 and VT2, VT0 and VT1, and VT2 and VT3. With such arrangement, only one kind of word line voltage is required when the address signal XO is '0'.;COPYRIGHT: (C)1996,JPO