phase change memory

A non-volatile, random access memory technology that is designed to initially replace flash memory and, potentially, DRAM memory. It employs the same phase change principle used in rewritable optical discs (CD-RWs, DVD-RWs, etc.). Also called "phase change RAM" (PRAM and PCRAM), chalcogenide RAM (C-RAM) and Ovonyx Unified Memory (OUM), Ovonyx, Inc., Rochester Hills, MI (www.ovonyx.com) is the pioneer in this field with patents that date back to the 1960s. Via licensing agreements with Ovonyx, Samsung introduced a prototype and BAE Systems introduced its C-RAM chip in 2006.

Memory Vs. Disk
In phase change technology, the bit is switched between amorphous (unstructured) and crystalline (highly structured) states. However, in phase change memory, the bits are altered by electricity rather than by laser as in optical discs. Phase change memory bits are also denser than the bits in optical discs. See phase change disc, chalcogenide glass and future RAM chips.