Samsung Electronics Co. Ltd. in Korea says it has completed the industry's first working prototype of a 512-Mbit phase-change randomaccess memory (PRAM). The device could replace high-density NOR Flash memories within the next decade, says the company.

PRAM incorporates vertical diodes in a 3D transistor structure that the company now uses to build DRAMs. PRAM is said to have the smallest cell size of any current memory — half that of NOR Flash — and is free of intercell noise, allowing virtually unlimited scalability. PRAM combines the fast processing speed of RAM for operating functions, with nonvolatile Flash memory for storage.

The architecture lets PRAM rewrite data without having to first erase previous data, making it effectively 30× faster than conventional Flash memory. It should also last 10× longer than conventional Flash memory, Samsung adds. In addition, PRAM needs 20% fewer processing steps than NOR Flash, so it is cheaper to produce. PRAM will initially target multifunction handsets and other mobile applications. Samsung says look for PRAM sometime in 2008.