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Xilinx Synthesis Technology User Guide

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HDL Coding Techniques<br />

Single-Port RAM with "false" Synchronous Read<br />

The following descriptions do not implement true synchronous read<br />

access as defined by the Virtex block RAM specification, where the<br />

read address is registered. They are only mappable onto Distributed<br />

RAM with an additional buffer on the data output, as shown below:<br />

WE<br />

DI<br />

A<br />

CLK<br />

Distributed<br />

RAM<br />

X8977<br />

The following table shows pin descriptions for a single-port RAM<br />

with “false” synchronous read.<br />

IO Pins Description<br />

clk Positive-Edge Clock<br />

we Synchronous Write Enable (active High)<br />

a Read/Write Address<br />

di Data Input<br />

do Data Output<br />

XST <strong>User</strong> <strong>Guide</strong> 2-135<br />

D<br />

DO

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