Cypress’s QDR-II is a high performance, dual-port SRAM memory. QDR-II SRAM offers a maximum speed of 333 MHz, densities up to 144 Mb, read latencies of 1.5 or 2.5 cycles, burst length of 2 or 4, and is available in an industry-standard 165-ball FBGA package.
The QDR-II family also includes double data rate (DDR-II) devices. DDR-II devices are similar to QDR-II devices except that all DDR devices have a burst length of 2 and a single data rate address bus. Additionally, DDR-II is available in SIO (separate I/O) or CIO (common I/O) options. SIO devices provide independent read and write ports, eliminating the data bus “turnaround” time found in CIO devices. CIO devices provide a single port for reads and writes, reducing the number of required data pin connections.