SleepyEgg

Intel is just one of the semiconductor companies that has been working on phase-change memory (PCM) for the past few years, and now the chipmaker and its collaborator, Numonyx, have hit on a way to increase PCM densities by stacking memory arrays on top of one another. They've demonstrated at 64Mbit memory using the stacking technique, which they plan to describe in a paper at the forthcoming IEDM conference.

PCM, which combines the speed of DRAM and the non-volatility of flash memory, has been the subject of much excitement since it was first proposed in the 70s. The basic idea behind the technology is that each memory cell consists of a small chunk of a special alloy that changes its physical characteristics and electrical properties (i.e., it changes phase) in response to how it is heated and cooled. The alloy's temperature is manipulated by injecting an electrical current into it, and the applied voltage level and timing of the injection determine which phase it ends up in.