Numonyx CTO Lays Out Road Map for Phase-Change Memory

Phase-change memory, which stands to replace DRAM and other components in digital devices during the next five years, offers a great deal of promise for the entire IT industry. It is blazingly fast, reliable and versatile. However, it is expensive, and in the current economic climate it has been a tough sell as a replacement technology.

SANTA CLARA, Calif.-Numonyx CTO Ed Doller laid out the differences in latencies between spinning disk hard drives, solid-state NAND flash drives and phase-change memory in terms that a lay person can readily understand.

Numonyx CTO Ed Dollar with PCM wafer.

"There are some very big differences, and processes in the future are only going to be demanding more speed," Doller told a near-capacity audience of several hundred people Aug. 11 in a keynote at the fourth annual Flash Memory Summit here at the Convention Center.
"I live in the world of milliseconds, nanoseconds and microseconds, but to normalize things, I'm going to make this more familiar to a wider audience," Doller said.
"Here it is: If I assume that random latency in a PCM device is one day-let's say it takes me one day to go to my PCM, get the information randomly and bring it back. In a solid-state drive, it [that same operation] would take 17 days to get that information back. How does that compare to a hard disk drive? Nine years!"
Doller then went a step further. "Let's say I'm going to put my PCM interface right on my processor, and I'm going to use PCM as storage-class memory-which means I'm going to execute code directly out of the PCM. Well, then it [the latency] goes from one day to 30 minutes," Doller said.
Therein lies the value of phase-change memory: speed that conventional data storage drives have never seen before-and never will.
A phase-change memory chip-it is also known as PRAM-is nonvolatile memory that works well for both executing code and storing large amounts of data, giving it a superset of the capabilities of both flash memory and dynamic random access memory. This means it can execute code with performance, store larger amounts of memory and also sustain millions of read/write cycles.
Intel debuted the first PCM chips at its developers' conference in San Francisco in September 2006.
The wafer shown to eWEEK that day represented Intel and Italy's ST Microelectronics' first grasp of the new type of nonvolatile memory chip. The two companies later merged to create Numonyx.
A great deal of development has been completed at Numonyx since then; Doller said that the adoption by mainstream IT companies has been slow but that it would take use by only a couple of big names-Apple and Microsoft would be two of them-for PCM to take off into the market stratosphere.
"PCM is on the verge, and we think it's inevitable that it will replace a lot of what is in devices today," Doller said. "But to start, it would take a company that is good at producing both hardware and software to make best use of it. It's bound to happen."
Adoption Curve Slow but Expected to Speed Up
Doller thinks PCM will need three to five more years to attain widespread adoption. Right now, the biggest drawback in PCM is the price, which is about 10 times higher than DRAM at this point. The pricing, however, will come down over time and as fabricating processes become improved.
PCM chips use the same material, chalcogenide, that is used inside to store data in rewritable optical disks. But instead of using a laser to change the properties of the material and thus create the zeros and ones that make up data, the chips use electricity that flows through a resistor. The resistor heats up and does the job of the laser, changing the materials' properties to represent a zero or a one.
The effort is the "culmination of [work by] some of the smartest materials guys on the planet," Doller said. "Over the years, this has an opportunity to be a very large memory technology."
Most industry people and analysts strongly believe PCM has the potential to replace both NAND-flash memory designed primarily for data storage-and NOR flash memory, designed for executing code with one type of chip, streamlining manufacturing processes.
PCM: 'Nirvana' for an Engineer
"PCM is like a superset of NOR or NAND flash," Doller said. "It's almost nirvana for an engineer. It reads fast, writes fast-it does everything faster."
Doller said the kind of speed PCM brings is going to be needed three to five years from now "just to index the Internet."
"We're bringing up a new generation that is used to instant-on," Doller said. "They expect to get things instantly.
"For example, my daughter was texting people on her iPhone instead of doing her homework recently. I asked her to stop texting her friends and go into her room, get on the PC and do her homework. She said, 'Dad, I am doing my homework.' Turns out she was doing it on her iPhone. She didn't want to use the PC because it took too long to spin up."

Chris Preimesberger

Chris J. Preimesberger

Chris J. Preimesberger is Editor-in-Chief of eWEEK and responsible for all the publication's coverage. In his 15 years and more than 4,000 articles at eWEEK, he has distinguished himself in reporting...