Each block RAM port has control over data width and address depth (aspect ratio). The true dual-port block RAM extends this flexibility to read and write where each individual port can be configured with different data bit widths. For example, port A can have a 36-bit read width and a 9-bit write width, and port B can have an 18-bit read width and a 36-bit write width.
If the read port width differs from the write port width and is configured in WRITE_FIRST mode, DOUT shows valid new data for all the enabled write bytes. The DOUT port outputs the original data stored in memory for all not-enabled bytes.
Independent read and write port width selection increases the efficiency of implementing a content addressable memory (CAM) in block RAM. This option is available for all UltraScale architecture-based devices true dual-port RAM port sizes and modes.