In a flat-cell ROM including a plurality of memory banks, each of the memory banks comprises a memory array, a plurality of bit lines, a plurality of virtual ground lines, three select lines, and a common row of contacts shared with an adjacent memory bank. The common row of contacts are used for connecting the bit lines and virtual ground lines to bit signal lines and virtual ground lines, respectively, and the select lines are used for selecting memory cells in the memory array. With a common row of contacts shared by two adjacent banks, the ROM area is reduced.