The MX25L1605D is 16,777,216 bit serial Flash memory, which is configured as 2,097,152 x 8 internally. When it is in two I/O read modes, the structure becomes 8,388,608 bits x 2. The MX25L3205D is 33,554,432 bit serial Flash memory,which is configured as 4,194,304 x 8 internally. When it is in two I/O read modes, the structure becomes 16,772,216 bitsx 2. The MX25L6405D is 67,108,864 bit serial Flash memory, which is configured as 8,388,608 x 8 internally. When it is in two I/O read modes, the structure becomes 33,554,432 bits x 2. (please refer to the “Two I/O Read mode” section).The MX25L1605D/3205D/6405D features a serial peripheral interface and software protocol allowing operation on a simple3-wire bus. The three bus signals are a clock input (SCLK), a serial data input (SI), and a serial data output (SO). Serialaccess to the device is enabled by CS# input