Embedded DRAM (eDRAM) is dynamic random-access memory (DRAM) integrated on the same die or multi-chip module (MCM)[1] of an application-specific integrated circuit (ASIC) or microprocessor.
eDRAM's cost-per-bit is higher when compared to equivalent standalone DRAM chips used as external memory, but the performance advantages of placing eDRAM onto the same chip as the processor outweigh the cost disadvantages in many applications.
In performance and size, eDRAM is positioned between level 3 cache and conventional DRAM on the memory bus, and effectively functions as a level 4 cache, though architectural descriptions may not explicitly refer to it in those terms.
Embedding memory on the ASIC or processor allows for much wider buses and higher operation speeds, and due to much higher density of DRAM in comparison to SRAM,[citation needed] larger amounts of memory can be installed on smaller chips if eDRAM is used instead of eSRAM.
eDRAM requires additional fab process steps compared with embedded SRAM, which raises cost, but the 3× area savings of eDRAM memory offsets the process cost when a significant amount of memory is used in the design.