Dense Approximate Storage in Phase-Change Memory

Multi-level phase-change memory stores bits by quantizing the resistance value of each cell. For example, a PCM cell with four distinct resistance levels can store two bits. By dramatically increasing this granularity, high density can be achieved at the cost of storage reliability. Many applications—those that deal with sensory data or are otherwise resilient to errors—can take advantage of this increased density with only small impact on overall quality of service. We present a very basic evaluation that suggests that approximate PCM storage may be a good option for lossy image storage.