Abstract: A delay circuit using MOS transistors for use of load capacitance which produces a stable delay effect for variations in signal voltage is provided. A gate of a P-type MOS transistor for load capacitance and a gate of an N-type MOS transistor for load capacitance are connected to a signal line. A resistor and CMOS inverters are used to apply a boosted voltage higher than a supply voltage VDD to a source-drain of the P-type MOS transistor for load capacitance and a substrate voltage lower than a ground voltage to a source-drain of the N-type MOS transistor for load capacitance. As a result, a gate voltage range for allowing the MOS transistors for load capacitance to have a capacitance is extended, and a stable delay effect is assured for a widened variation of signal current flowing on the signal line.

Abstract: A flat NOR type mask ROM includes a plurality of bit-lines that are parallel to each other, a plurality of memory cells provided between adjacent bit-lines and a plurality of word-lines that are parallel to each other and orthogonal to the bit-lines, each word-line being connected to a plurality of the memory cells. The memory cells provided every predetermined number of bit-lines are OFF-cells which are always in an OFF state regardless of a potential level of the respective word-line.