IBM added two features to make the new form of PCM possible. One is a way to adjust for so-called “drift,” which can gradually degrade the memory’s ability to store the right values. The other counters the effects of heat on PCM so it can run reliably in normal system temperatures.
Another piece of the puzzle is how to get the data to the processor without slowing down the data on the way. IBM’s betting on CAPI (Coherent Accelerator Processor Interface), a high-speed protocol it uses in Power-based servers. CAPI runs on top of the PCIe physical interface.
IBM isn’t predicting when three-bit PCM will be in mass-market systems, partly because the company doesn’t make memory and will have to find a partner. (It’s cooperated with SK Hynix on PCM in the past.) But it might take two to three years for large-scale availability, the company said.
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