Differences between UltraRAM and Block RAM - 2025.2 English - UG901

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

• UltraRAM provides only one clock. Although it supports true dual-port operation, both ports share that clock and operate synchronously.
• Unlike block RAM, you cannot configure the UltraRAM aspect ratio. It is always configured as 4K x 72.
• 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.