Intel is about to sample non-volatile phase-change random access memory (PCM or PRAM) as a drop-in replacement for NOR flash memory, the type used in mobile phones. PRAM has the potential because of its size and access speeds to replace some DRAM applications as well as the longer-lasting but slower NAND flash memory used in digital cameras and beginning to appear in hybrid disk drives.
Most random access memory suppliers are investigating PRAM. Intel says that it has built a 128Mbit PRAM device, using 90nm technology, which demonstrated 100 million read-write cycles. Flash memory chips have a far lower read-write cycle maximum and some fail after just 10,000 cycles. Intel's chip has a claimed 10-year or greater data retention period, is smaller than equivalent capacity flash memory, and uses the same power. The company didn't reveal its PRAM access time but Hitachi has demonstrated a 20ns latency. This is much quicker than flash memory's 50-90ns latency but significantly slower than DDR2 RAM which is around 3ns.
Intel intends to identify and fix any problems with PRAM in the NOR flash area and then move the technology up the memory hierarchy to NAND flash. If it can get the access speed down even lower then DRAM applications could also move to PRAM. An attraction would be that PRAM doesn't need the power-hungry constant refreshing needed by DRAM. Intel is talking of PRAM as a kind of memory nirvana.
Other potential PRAM applications include much faster and capacious USB thumb drives and solid-state disk drives. Hybrid disk drives and the Intel Robson motherboard with flash cache, could also have larger and significantly faster cache memory leading to better performance.
Elpida, IBM, Intel, Macronix, Qimonda and Samsung are all licensing PRAM technology from Ovonyx which owns the core intellectual property. Intel Capital invested in Ovonyx in 2000 and made an additional investment in 2005. Intel is not saying what capacity devices it will sample but Samsung already has 90nm 256Mbit and 512Mbit sample parts available. Intel expects Moore's law to apply to PRAM technology development in terms of cell size and speed.
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