DRAM – The Memory Guy Blog

Valuable Memory Technical Resources

Ever since moving to Silicon Valley some time ago The Memory Guy has worked with a number of impressively-talented engineers from India. Some are educated in the US, while others are educated in India. One university that produces excellent engineers is the Indian Institute of Technology, or IIT.

It comes as no surprise, then, to find a valuable resource produced by an IIT faculty member. Dr. Sparsh Mittal, an assistant professor at IIT Hyderabad, reached out to me to share some papers that he thought might be of interest to Memory Guy readers. They were a few of roughly 40 papers that he has posted on his publications page. He explained that he previously worked at Oak Ridge National Lab, in the US.

Dr. Sparsh has published several very comprehensive surveys on memory systems, both conventional and emerging, covering topics like DRAM reliability, NVM/Flash, ReRAM-based processing-in-memory, and the architecture of neural networks. The web page lists 34 surveys, eight of them Continue reading “Valuable Memory Technical Resources”

Why DRAM is Threatened by SSDs

Conventional wisdom holds that SSDs will someday displace all HDDs, but in reality SSDs are proving to be more of a challenge to the DRAM market than to the HDD market.

Right now you are probably reviewing the date of this post to make sure it’s not dated April 1. I assure you that this is the truth. To understand it, though, you must look at a computer as a computer architect would, or, in other words, the way that an application program sees the memory/storage hierarchy.

To the application program there is no HDD and memory, there is only memory. The Virtual Memory system, a part of the operating system, hides the difference between the two by moving code and data into DRAM as it is needed and back onto the HDD when it is no longer important, without telling the application program that it is moving anything around. I like to tell people that the DRAM makes the HDD look fast, and the HDD makes the DRAM look big.

If you think of the DRAM as something that makes the HDD look fast, then additional DRAM should help to make the Continue reading “Why DRAM is Threatened by SSDs”

Super-Cooled DRAM for Big Power Savings

Recently Rambus announced that it was using cryogenic temperatures to boost computer performance in large datacenters. This research is being done in a joint project with Microsoft who is developing a processor based on Josephson Junctions.

This is an effort to provide a performance increases greater than can be attained through standard semiconductor scaling. The research project aims to attain improvements in cycle time, power consumption, and compute density, leading to better energy efficiency and cost of ownership (COO). The companies hope to gain side benefits of being able to squeeze more bits onto a DRAM chip thus reducing cost per bit, improving performance, and making DRAM chips less costly to produce.

The system these two companies are researching uses a memory system that is cooled to 77 degrees Kelvin (77°K) with a processor that operates at 4°K. To do this the memory system is bathed in liquid nitrogen while the processor is cooled by liquid helium. The temperatures are the boiling points of these two liquids.

Surprisingly, the fact that these two subsystems are in different Continue reading “Super-Cooled DRAM for Big Power Savings”

Is Micron Being Acquired?

The following is an excerpt of an Objective Analysis Alert sent to our clients 7/13/15.

A July 13 Wall Street Journal article disclosed that China’s state-owned Tsinghua Unigroup has bid to buy Micron Technology for $21 a share or $23 billion, which would make this the largest-ever Chinese takeover of a U.S. company.

Objective Analysis has been telling our clients for the past few years that either China or India would create a new DRAM/NAND manufacturing company, especially since memory chip makers have enjoyed a long period of profits, and this usually motivates outsiders to invest in new DRAM makers. We did not anticipate an acquisition.

Countries with heavy industry typically move into the semiconductor business during an extended upturn, and become DRAM suppliers since DRAM is an undifferentiated commodity. Commodities sell almost solely on price and success is based on little more than manufacturing strength. This is a business model that industrial economies understand.

In addition to Micron’s tangible assets, including Continue reading “Is Micron Being Acquired?”

What Memory Will Intel’s Purley Platform Use?

There has been quite a lot of interest over the past few days about the apparently-inadvertent disclosure by Intel of its server platform roadmap. Detailed coverage in The Platform showed a couple of slides with key memory information for the upcoming Purley server platform which will support the Xeon “Skylake” processor family. (A review of this post on 7/13/17 revealed that The Platform’s website has disappeared. The above link and the next one no longer work.)

One slide, titled: “Purley: Biggest Platform Advancement Since Nehalem” includes this post’s graphic, which tells of a memory with: “Up to 4x the capacity & lower cost than DRAM, and 500x faster than NAND.”

The Memory Guy puzzled a bit about what this might be. The only memory chip technology today with a cost structure lower than that of DRAM is NAND flash, and there is unlikely to be any technology within the leaked roadmap’s 2015-2017 time span that will change that. MRAM, ReRAM, PCM, FRAM, and other technologies can’t beat DRAM’s cost, and will probably take close to a decade to get to that point.

Since that’s the case, then what is this mystery memory? If we think of Continue reading “What Memory Will Intel’s Purley Platform Use?”

DRAM Prices Down, But Not So Bad

For the past ten months DRAM prices have been undergoing a steady slide. Is the market in a crisis? Not really!

Today’s low spot price of $4.30/GB puts us on a par with February 2013, a full two years ago (see chart). DRAM makers have done a lot to reduce their production costs since that time, so their margins this quarter will be much better than they were in the first quarter of 2013.

But we are still a very long way from the bottom of the last market downturn. In late 2012 spot prices reached a low of $2.52/GB, a full 41% lower than today’s lowest spot prices.

The Memory Guy models the production costs of leading memory chips, and DRAM manufacturing costs have been decreasing for the past several years at an average annual rate of about 30%. That means that costs today are about half of what they were two years ago, and one third of their level this time in 2012.

So even though today’s Continue reading “DRAM Prices Down, But Not So Bad”

Backing Out DRAM Process Rules

Inotera recently announced earnings and posted an impressive 55% gross margin. Inotera is a pure-play DRAM maker, so it’s not too difficult to estimate the company’s process geometries based on its financials.

The Memory Guy thought it might be interesting to determine what I could from the 55% gross margin number.

First of all we can estimate Inotera’s manufacturing cost/GB based on the gross margin and an assumption about the company’s sales price/GB. The WSTS price per gigabyte for November was $7.83. Assuming that Inotera’s ASP was equal to this number, then at a gross margin of 55% the company’s cost/GB would have been $3.52.

Inotera’s acts as a foundry for Micron Technoogy. If Inotera sold to Micron at some lower price, then Inotera’s production costs would necessarily be proportionally lower to maintain the same gross margin.

Using the WSTS price: At a processed wafer cost of $1,600 (my rule of thumb) a $3.52/GB cost would require 454 8Gb dice to be produced Continue reading “Backing Out DRAM Process Rules”

Memory Issues in Space & Medical Applications

The Memory Guy was recently asked about using memories in a satellite. What would be a good technology to use in a space application?

The problem with space is that there is a lot of radiation. Radiation on the earth’s surface is lower because it is stopped by the atmosphere, but in space there is an abundance of radiation that interferes with most semiconductors. Radiation is also a concern in certain medical applications where a memory must maintain its contents while undergoing sterilization through irradiation. Experiments on conventional flash memories have shown data loss at only 2% of the Continue reading “Memory Issues in Space & Medical Applications”

Fundamentals of Memory – Free Online Course

Some time ago The Memory Guy was asked by Numonyx (later acquired by Micron) to put together an online course for EE Times on memory technologies, explaining how each one works and where it is used.

Although the course was very well received, I never posted a link to it on The Memory Guy blog. This post is intended to correct that error.

The course runs 75 minutes and covers the basics of DRAM, non-volatile RAM, SRAM, NAND flash, NOR flash, mask ROM, and EEPROM. It explains each technology’s advances in size, cost and performance, leading up to the development of Continue reading “Fundamentals of Memory – Free Online Course”

Is the DRAM Market Entering a Shortage?

Long-term clients of mine, even those dating back to my decade at Dataquest in the 1990s, are familiar with the concept that spot prices behave differently during a shortage. When there is too much DRAM spot prices remain below contract prices, because OEMs who bought too much product clear their inventory at quarter end (and other times) by selling at a loss.

During a shortage the opposite is true: OEMS find that they can’t get as much DRAM as they wanted through their contract sources, so they shop for the balance on the spot market. Since there are more buyers than sellers, spot prices invariably raise higher than contract prices.

When the prices change from one state of affairs to the other then it is safe to assume that Continue reading “Is the DRAM Market Entering a Shortage?”