What is DDR4 !!

Do almost anything often enough, and the individual steps become routine. It certainly feels that way when I’m building computers: There are days I feel like I could do it in my sleep (and, truth be told, there are days I probably have). But when you’re selecting parts, most of the components require at least a little analysis. The CPU and the motherboard are major, and have to be considered together. Of course storage is a big deal — you always want enough and you always want it to be fast, and optimizing those qualities with affordability can be a headache (especially at the moment). For a gaming system, the right video card is essential. And in addition to being your system’s face to the world, the case will affect both the way you build the computer and how much you can expand it later. And… that’s it. Right? Am I forgetting anything?

Oh yeah, RAM. Sorry about that. But I admit it: When I’m shopping for memory, I pretty much turn off my brain. It’s not intentional, and it’s not that I think RAM isn’t important. It’s just that it’s the easiest kind of hardware to shrug off. Most of us, even when we’re in our most rabid enthusiast mode, roll our eyes at the arcane industry of RAM timings. Provided the DIMMs’ voltages and speeds are compatible with the motherboard, everything else usually seems academic. Oh, if I’m being super picky about components, I might pay a bit more attention, but in reality that’s rarely necessary. These days, you can take it for granted that basic DDR3 is going to be what you want.

It occurred to me last week, however, that we’re rapidly approaching another time when that might not be the case. As processors and other hardware get more powerful, it becomes more difficult — and important — for RAM to keep up. Over the last 20 years or so we’ve seen single data rate (SDR) memory give way to double data rate (DDR) memory, which transfers data on both the rising and falling edges of the clock signal. And over the last decade, we’ve slowly progressed from DDR to DDR2 (with an internal clock running at half DDR’s rate) to DDR3 (operating at half DDR2’s rate), constantly upping performance while reducing power usage along the way. But what about the next logical step in this particular cycle: DDR4?

It’s coming, though when — and whether — you’ll see it for use in your home computer is still somewhat up in the air.

Samsung announced a year ago that it haddeveloped the first 2GB DDR4 modules using a 30nm process technology, achieving with them transfer rates of 2.133Gbps at 1.2 volts. Three months later, Hynix came up with its own DDR4-2400 modules operating at the same voltage.

The website DDR4.org, which is (not surprisingly) devoted to information about the upcoming memory standard, is a bit light on substantive information but fleshes out a few of the details. Among them: Data transfer rates would start at 2,133MT/s (about where DDR3 is leaving off) and could eventually double to 4,266MT/s, and initial energy consumption is expected to be about 1.2 volts (though later chips might be able to use as little as 1.05 volts). The site goes on to say that “other sources have noted that the [power] consumption is 40 percent less for DDR4 than for an equivalent DDR3 chip.” Not bad. Another nugget of useful information on the site is the mention that DDR4 might make use of “pseudo open drain” technology, which was adapted from GDDR memory.

Laser-switched magnetic storage

1,000 times faster than current hard drives 

  Hold onto your hats: An international team of scientists working in England, Russia, Switzerland, and the Netherlands have completely rewritten the rules of magnetic storage. Instead of switching a magnetic region using a magnetic field (like a hard drive head), the researchers have managed to switch a ferrimagnetic nanoisland usinglasers. Storing magnetic data using lasers is up to 1,000 times faster than writing to a conventional hard drive.

   To achieve this, the researchers created ferrimagnetic nanoislands (pictured above) out of an alloy of iron and gadolinium (a rare earth metal). When these nanoislands are struck by a 60-femtosecond laser (0.06 picoseconds, or 0.00006 nanoseconds) their magnetism switches (pictured below). If you know a little about the science of magnetism, you’ll know that this behavior is rather funky as we usually associate heat with destroying magnetism, rather than switching it.

In total, it takes a nanoisland five picoseconds to switch state (from binary 0 to binary 1). By comparison, it takes about one nanosecond to switch the value of a magnetic region on a hard drive platter. In other words, we are looking at a storage technique that’s about 1,000 times faster than current hard drives. Instead of storing hundreds of megabytes per second, the use of femtosecond lasers would enable the transfer of gigabytes or terabytes per second.

That’s not all! Current hard drive platters have a density of around three terabits per square inch, but nanoislands are so small that you could cram in 53 terabits per square inch. Instead of a terabyte per platter, we would be looking at 15 terabytes per platter and 45TB hard drives. Apparently femtosecond lasers are more efficient than spinning a hard drive head around at thousands of RPM, too, though the researchers don’t give any hard figures.

Finally, though, it’s worth noting that the scientists only discuss how to write data, not read. Ferrimagnets, like antiferromagnets, don’t generally have a magnetic field. In other words, York’s nanoisland storage medium can’t simply replace a hard drive platter. At the moment, data is probably read using a scanning tunneling electron microscope — and for the time being, they’re still very much room-sized devices