The SN74ACT3651 is a high-speed, low-power, CMOS clocked FIFO memory that supports clock frequencies up to 67 MHz and has read access times as fast as 11 ns. The 2048 × 36 dual-port SRAM FIFO buffers data from port A to port B. The FIFO memory has retransmit capability, which allows previously read data to be accessed again. The FIFO has flags to indicate empty and full conditions and two programmable flags (almost full and almost empty) to indicate when a selected number of words is stored in memory. Communication between each port takes place with two 36-bit mailbox registers. Each mailbox register has a flag that signals when new mail has been stored. Two or more devices are used in parallel to create wider data paths. Expansion is also possible in word depth.