UltraRAM Readback and Writeback v1.0 Product Guide (PG356) - 1.0 English - The Xilinx® UltraRAM (URAM) is a high-density synchronous memory introduced in the UltraScale+™ family. UltraRAMs do not support the Readback as well as Writeback (initialization) functionality that is required debug features for emulation and prototyping.