  Storage Class Memory (SCM) is a class of memory technology which has recently
become viable for use. Their namearises from the fact that they exhibit
non-volatility of data, similar to secondary storage while also having
latencies comparable toprimary memory and byte-addressibility. In this area,
Phase Change Memory (PCM), Spin-Transfer-Torque Random Access Memory(STT-RAM),
and Resistive RAM (ReRAM) have emerged as the major contenders for commercial
and industrial use. In this paper, wedescribe how these memory types function,
while highlighting the problems of endurance and performance that these memory
typesface. We also discuss the future possibilities of Multi-Level Cells
(MLCs), as well as how SCM can be used to construct accelerators.
