A mask ROM includes bit lines, word lines intersecting with the bit lines and bit cells provided along the word lines, each of the bit lines being formed of a cell transistor having a gate connected to an associated one of the word lines. In the mask ROM, further provided is a source node commonly connected to respective sources of ones of the cell transistors having a gate connected to one of adjacent two word lines. A current flows from a selected bit line to a non-selected bit line via a cell transistor selected in reading out data and the source node.
An electronic circuit can include a first memory cell and a second memory cell. In one embodiment, source/drain regions of the first and second memory cells can be electrically connected to each other. The source/drain regions may electrically float regardless of direction in which carriers flow through channel regions of the memory cells. In another embodiment, the first memory cell can be electrically connected to a first gate line, and the second memory cell can be electrically connected to a greater number of gate lines as compared to the first memory cell. In another aspect, the first and second memory cells are connected to the same bit line. Such bit line can electrically float when programming or reading the first memory cell or the second memory cell or any combination thereof.
