2.1.1.2 Block Select Operation

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In Dual-Port mode, to perform two independent write and read operations (on Port A, Port B, or both) the block select signal is required. Table 2-4 lists the block select operation for Port A and Port B.

Table 2-4. Block Select Operation
A_BLK_EN[2:0]	B_BLK_EN[2:0]	Operation
Any one bit = 0	Any one bit = 0	No operation on Port A or B. The data output A_DOUT[19:0] and B_DOUT[19:0] will be forced zero.
Any one bit = 0	111	Read or write operation on Port B
111	Any one bit = 0	Read or write operation on Port A
111	111	Read or write operation on both Ports A and B

When the pipeline registers are enabled, the effect of the block select at the outputs is delayed by one clock cycle, as shown in the following figure.

Figure 2-3. Block Select Inputs for Dual-Port Mode