The 18Mb IS61QDB451236A and IS61QDB41M18A are synchronous, high-performance CMOS static random access memory (SRAM) devices. These SRAMs have separate I/Os, eliminating the need for high-speed bus turnaround. The rising edge of K clock initiates the read/write operation, and all internal operations are self-timed. Refer to the Timing Reference Diagram for Truth Table for a description of the basic operations of these QUAD (Burst of 4) SRAMs. Read and write addresses are registered on alternating rising edges of the K clock. Reads and writes are performed in double data rate. The following are registered internally on the rising edge of the K clock: