Non-Volatile Memory: Emerging Technologies And Their Impacts on Memory Systems

For almost 30 years, computer memory systems have been essentially the same: volatile, high speed memory technologies like SRAM and DRAM used for cache and main memory; magnetic disks for high-end data storage; and persistent, low speed ash memory for storage with low capacity/low energy consumption requirements such as embedded/mobile devices. Today we watch the emergence of new non-volatile memory technologies, such as PhaseChange RAM (PCRAM), Magnetoresistive RAM (MRAM) and Resistive RAM (RRAM), that promise to radically change the landscape of memory systems. This paper summarizes the current state of memory system design, presents these new memory technologies and surveys the current proposals on how to apply these technologies to improve memory hierarchies. We conclude that the introduction of these new technologies will probably result in more complex memory hierarchies, but is likely to allow the construction of memory chips that are non-volatile, low-energy and have density and latency close to or better than current DRAM chips, improving performance/e ciency and allowing memory systems to continue to scale up.