Intel Doubles Capacity of Likely Flash Successor

Intel has announced a new technique that allows them to effectively double the storage capacity of a single phase-change memory cell without adding cost to the current fabrication process. "Phase-change memory differs from other solid-state memory technologies such as flash and random-access memory because it doesn't use electrons to store data. Instead, it relies on the material's own arrangement of atoms, known as its physical state. Previously, phase-change memory was designed to take advantage of only two states: one in which atoms are loosely organized (amorphous), and another where they are rigidly structured (crystalline). But in a paper presented at the International Solid State Circuits Conference in San Francisco, researchers illustrated that there are two more distinct states that fall between amorphous and crystalline, and that these states can be used to store data."

Re:Two Billion Transistors on Their Latest Chip

[networkBoy]

PCM litho tech in not compatible with CPU litho tech.
So I doubt this will be happening any time in the near future.
-nB

Re:Two Billion Transistors on Their Latest Chip

[SirLoadALot]

No, processor caches are made out of SRAM, which is very fast but takes a lot of silicon space. Flash and phase-change RAM are totally different technologies. They aren't intended to be as fast as SRAM, but they are non-volatile, storing their contents without power. Phase-change or a similar technology may end up giving DRAM a run for its money if it gets fast enough, but I've never heard of an alternative to SRAM for internal processor caches.

Re:Only Double?

[nonsequitor]

It's double the number of bits. If you look at the largest value a 16 bit number or a 32 bit number can store, its not "double" in size. When it comes down to it, they're just bits, how you use them is up to you.

Re:Only Double?

[SirLoadALot]

Currently the phase change RAM can only store 1 bit per element, in two possible states -- 0 or 1. They are changing this four possible states, which corresponds to two bits -- 00, 01, 10, 11. Hence, the amount of data that can be stored is doubled. The number of bits held per element increases by one every time the number of possible states is doubled.

Re:Only Double?

[wizardforce]

Now, if you are using binary storage, and each bit stores 1 of 2 values, then you have the possibilities of: 00,01,10,11. Which is 4 different values. Now if you have 4 states for each bit (which I guess wouldn't, by definition, be a bit anymore), then you have 00,01,02,03,10,11,12,13,20,21,22,23,30,31,32,33. So, you have have squared the amount of information you can store.

simply put, no. 1 bit can either be 0 or 1 *not* 00, 01, 10, 11, that would be TWO bits. doubling the number of combos for one "bit" would likely be stored as 00,01,10,11 although what you're actually doing here is storing 0001 and 1011 together hence two "bits" of info can be stored per unit in a 4 state system.

Re:No longer binary?

[disassembled]

Will we now have computers that do base 4 arithemetic rather than base 2?

A base-4 digit is the same as two base-2 digits, information-wise, so it doesn't really matter how the information is stored. If you want to store a byte in some piece of hardware, you can store it as 4 base-4 values or 8 base-2 values, and it'll all look the same to the CPU.

Re:Salt shaker please

[Microlith]

as long as flash keeps getting bigger and cheaper we won't see it's 'Successor' for a while.

As I understand it, flash (nand) capacity grows with the shrinking of the trace size. It's also cheap because it's produced in mass quantities.

Everything that has made flash high capacity and cheap can be applied to PCM, only PCM has a number of advantages:
- more durable, since it doesn't force high voltages over blocks to erase them
- smaller cells, allowing more to be packed in the same space
- rewriteability. You don't have to erase a block to change a single byte. It's more like RAM or hard disks in that respect.

So what will likely happen is a slow change from FLASH to PCM as the major flash manufacturers transition their products to this technology. It'll still have the same form factor, and most people won't notice aside from an increase in capacity.

IANAPCMEBIWNS (I am not a pcm expert but I work near some...)

Just like the MLC flash.

[Anonymous Coward]

The principle is similar to MLC flash (multi-level cell NAND flash), that also stores 2 bits per data element by using 4 different voltages. The tech behind this memory is completely different though.

Re:Only Double?

[Dan Posluns]

Another way of looking at it:

Say we use a bit to store the result of a coin toss. True for heads, false for tails.

With two bits, we can store the results of two coin tosses. There are four possible outcomes when two coins are tossed, ranging from neither of them being heads, to only the first or the second being heads, or both of them being heads.

If we double the number of bits, we can store the result of four coin tosses. There are now sixteen possible outcomes, but we're still only storing the result of four tosses.

(Note that this example assumes we're interested in storing off the result of each coin toss. If we're only interested in counting the total number of heads or tails and don't care which coin was tossed in what order, then we can use our bits to store the total number of successful tosses rather the result of each toss, which is a much more efficient use of our bits but carries less information.)

Dan.

Re:Two Billion Transistors on Their Latest Chip

[compro01]

I've never heard of an alternative to SRAM for internal processor caches.

AMD seems to be taking interest in Z-RAM for that purpose.

http://www.eetimes.com/news/semi/showArticle.jhtml?articleID=196601127 [eetimes.com]

Re:step backwards

[imgod2u]

Not really. If you think about it, fundamentally there just as many states a bunch of atoms can arrange itself in as counting electrons. You're really only bound by Plank's constant in how resistive or conductive a collection of atoms are. Assuming you had a device sensitive enough to detect the variation.

The trick is, of course, in how fast you can change those states. I would imagine electrons are much easier to move than whole atoms. I understand how read speed for PCM is faster than a transistor but writing....I don't know.