Intel and Micron have unveiled what appears to be the holy grail of memory. Called 3D XPoint (pronounced "cross point"), this is an entirely new type of non-volatile memory, with roughly 1,000 times the performance and 1,000 times the endurance of conventional NAND flash, while also being 10 times denser than conventional DRAM.

The first 3D XPoint memory chips will be sampled "later this year," but there's no official timeline for commercialisation. Importantly, however, Intel and Micron say that 3D XPoint is "affordable," which means we might actually see it in consumer-grade devices. Other new memory technologies, such as phase-change memory, have so far proven too expensive to compete with gloriously cheap DRAM and NAND.









So, what is this 3D XPoint thing?

Annoyingly, neither Intel or Micron are giving away technical details at this point. We've asked for a whitepaper or some kind of technical specification, but no dice.

In the words of Intel and Micron, 3D XPoint consists of a "transistor-less cross point architecture," where single-bit memory cells "sit at the intersection of word lines and bit lines." Intriguingly, and unlike NAND and DRAM, memory cells in 3D XPoint do not use electrical charge to store the binary value—but Intel and Micron won't say what they're using instead. If I had to guess, they're probably memristors.

In 3D XPoint, individual memory cells are read and written by simply applying a voltage to the appropriate word line and bit line. Unlike DRAM, there's no transistor governing each memory cell, which is one of the main reasons that 3D XPoint is (reportedly) much denser than DRAM.

If you look at the labelled image in the gallery above, it seems like each 3D XPoint die will have two layers of memory cells, and the dies will also be stackable for increased density. Intel and Micron are saying they've made individual 3D XPoint dies that can store 128Gb, which is very dense compared to state-of-the-art commercial DDR4 (8Gb per die), but not very dense compared to NAND (Micron itself is shipping 2Tb NAND dies).

Performance-wise, Intel and Micron make very bold claims: 3D XPoint is apparently "up to 1,000 times faster" and "has up to 1,000 times greater endurance" than commercial NAND chips.

If 3D XPoint isn't using electrical charge to store data, and is instead using a material that changes state, then the endurance figure is believable.

The performance figure is a bit trickier: when Intel and Micron say "faster," what do they actually mean? If the access time is 1,000 times faster than NAND, then that's actually quite believable. By way of comparison, DRAM latency is currently about 1,000 times faster than NAND. If 3D XPoint has 1,000 times more bandwidth than NAND, then we're probably back into fantastical-PR-claim territory.

Is this really the holy grail?

Over the years, a number of new memory technologies and architectures have been announced with much pomp and fanfare—RDRAM (Rambus), MRAM (magnetoresistive), ReRAM (resistive), PCM (phase-change memory), HMC (hybrid memory cube)—but so far, none of them have been able to unseat DRAM for main system memory or NAND flash for non-volatile storage. There are a number of reasons for this, but it mostly comes down to ease of manufacture and cost: DRAM and NAND are incredibly mature technologies that are dirt cheap to make.

According to Intel and Micron, 3D XPoint is cost-competitive with both NAND and DRAM. This is a very bold claim for a new technology, but considering these are two of the biggest semiconductor manufacturers in the world, we have to give them some benefit of the doubt.

Intel and Micron say that 3D XPoint has already entered production, and that it will be sampled "later this year with select customers." Intel and Micron are developing their own products based on the new technology. Given that 3D XPoint is fast, but not as dense as NAND, it's not entirely clear what market segment will be tackled first. The labelled diagram suggests that 3D XPoint could serve as both system memory and storage, replacing DRAM and NAND, but that would be a bold first step.

More likely, we'll probably see some hybrid memory devices: sticks of memory that have both DRAM and 3D XPoint soldered on, or hybrid drives with NAND flash for mass storage and 3D XPoint providing a faster cache.

Listing image by Intel