Differences between UltraRAM and Block RAM - 2022.1 English

Vivado Design Suite User Guide: Synthesis (UG901)

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2022.1 English

There are a few notable differences between UltraRAM and block RAM to consider, as follows:

°The UltraRAM only has one clock, so while true dual port operation is supported, both ports are synchronous to each other.

°The aspect ratio of the UltraRAM is not configurable like block RAM, it is always configured as 4Kx72.

°The resets on the output registers can only be reset to 0.   

°The write modes (read_first, write_first, no_change) do not exist in this primitive. The regular UltraRAM behaves like no_change; however, if you describe read_first or write_first in RTL, the Vivado synthesis creates the correct logic.

°Finally, the INIT for RAM does not exist, the UltraRAM powers up in a 0 condition.