Xilinx System Generator V2.1 Reference Manual page 111

Block Parameters Dialog Box
The block parameters dialog box can be invoked by double-clicking the icon in your
Simulink model.
Figure 3-74: Single Port RAM block parameters dialog box
Parameters specific to this block are:
Other parameters used by this block are explained in the Common Parameters section
of the previous chapter.
During a write operation (WE asserted), the data presented to the data input is stored
in memory at the location selected by the address input. During a write cycle, the user
can configure the behavior of the data out port A to one of the following choices:
Memory
Depth: specifies the number of words stored; must be a positive integer.
Initial Value Vector: specifies the initial value. When the vector is longer
than the RAM, the vector's trailing elements are discarded. When the RAM is
longer than the vector, the RAM's trailing words are set to zero.
Zero Initial Output: when checked, the data out ports have a value of zero
at clock 0; otherwise, they have a value of NaN ("not a number").
Write Mode: specifies the memory behavior to be Read Before Write, Read After
Write, or No Read On Write. There are device specific restrictions on the
applicability of these modes.
Use Distributed Memory (instead of Block RAM): when checked, the
block is implemented with distributed RAM; otherwise, it is implemented with
Block RAM.
Xilinx Blocks
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