[adsr]

I hope someone will give a push behind MRAM which seems like a more interesting option imo.

MRAM has similar performance to SRAM, similar density to DRAM but much lower power consumption than DRAM, and is much faster and suffers no degradation over time in comparison to flash memory. It is this combination of features that some suggest makes it the “universal memory”, able to replace SRAM, DRAM, EEPROM, and flash.

https://en.wikipedia.org/wiki/Magnetoresistive_random-access...

[david-given]

There's also FRAM, which has also been around for a while? I have an MSP430 microcontroller where the primary storage is 64kB of FRAM. It's great; performs like SRAM, but is totally persistent, and doesn't wear out.

The largest devices I've seen are 4Mb (512kB), which isn't a lot by PC standards, but is dead handy for embedded.

browses

Oho, they make one which is pin-compatible with SRAM chips!

http://www.fujitsu.com/global/products/devices/semiconductor...

Price looks like $15 a single part to $12 for ten. Ouch. If we assume that it's about $20 a megabyte in bulk, a gigabyte would cost about $20k. This is, price-wise, equivalent to:

- RAM, in 1996

- Spinning disk, in about 1988

- Flash, in about 1998 (extrapolation, my chart doesn't have nay data before 2004).

Ref: http://www.jcmit.com/memoryprice.htm

Today's statistics have been brought to you by Late, and Tired. Enjoy.

[aidenn0]

I'd like to see a source for the "similar density to DRAM" my understanding is that it's an 8F2 footprint, and scaling it down to small process nodes is still problematic, even with spin-torque transfer.

All that being said, there are people who make the exact same claims about RRAM as you quote for MRAM, which 3d-xpoint appears to be.

Also note that you can buy MRAM parts right now, which are replacements for battery-backed SRAM, and are more radiation resistant than SRAM. Densities are fairly low though.

[the8472]

> my understanding is that it's an 8F2 footprint

Where does that come from? From everything I've read is that its structure is fairly analogous to DRAM, "simply" replacing the capacitor with the magnetic tunnel junction, which has its component layers stacked vertically, thus not really taking up any extra space.

> scaling it down to small process nodes is still problematic, even with spin-torque transfer.

yeah, that's the main gist I'm getting too from following the news.

> people who make the exact same claims about RRAM as you quote for MRAM, which 3d-xpoint appears to be.

At least the xpoint incarnation still seems to be slower than DRAM according to that article, while MRAM is being offered as SRAM/battery-backed DRAM drop-in replacement.

[aidenn0]

>> my understanding is that it's an 8F2 footprint

> Where does that come from? From everything I've read is that its structure is fairly analogous to DRAM, "simply" replacing the capacitor with the magnetic tunnel junction, which has its component layers stacked vertically, thus not really taking up any extra space.

I did some searching; older references show an 8-12F2 size, for e.g. the Everspin parts. Grandis claims a 6F2 size which is indeed comparable to DRAM.

>> people who make the exact same claims about RRAM as you quote for MRAM, which 3d-xpoint appears to be.

> At least the xpoint incarnation still seems to be slower than DRAM according to that article, while MRAM is being offered as SRAM/battery-backed DRAM drop-in replacement.

Right, the product they are claiming they will manufacture next year is slower than DRAM and less dense than flash. (Frustratingly I couldn't find a reference for if they are talking about latency or throughput when they say "slower"; it makes a big difference for which applications will be hurt by the performance mismatch).

However, there doesn't appear (yet) to be a fundamental reason why resistive ram must always be slower than DRAM, nor a fundamental reason why they couldn't do MLC tricks with it, so you can't say all RRAM will be slower than DRAM and less dense than NAND.

[adsr]

Fair point, perhaps I should have phrased it more as a technology with similar applications. I find it interesting that there are parts available now, albeit made on a 180nm process apparently.

[the8472]

these guys claim 55nm mram: http://www.avalanche-technology.com/about/public-relations