| 摘要 |
A mask ROM small in circuit scale and low in consumption power has an n-type select transistor having a drain connected to a corresponding one of bit lines, a source connected to a data line and a gate for inputting a corresponding one of select signals. A p-type precharge transistor has a drain connected to a corresponding one of bit lines, a source connected to a power line VDD, and a gate for inputting a corresponding one of the select signals. Because the bit line is precharged by using a precharge transistor opposite in conductivity type to the select transistors, it is satisfactory to provide one precharge transistor for one bit line, greatly reducing the circuit scale.
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