Phase-change memory offers 100 times the write performance of NAND flash

By Lucas Mearian | Computerworld US | Published: 10:11, 01 July 2011

IBM Thursday announced a breakthrough in computer memory technology, which may lead to the development of solid-state chips that can store as much data as NAND flash technology but with 100 times the performance and vastly greater lifespan.

Currently, NAND flash memory products, such as SSDs, have write rates as high as 2Gbit/sec .

IBM said it has produced phase-change memory (PCM) chips that can store two bits of data per cell without data corruption problems, something that has plagued PCM development from the start.

IBM’s phase-change memory chip uses circuitry that is 90 nanometers in width

Like NAND flash memory, which is used in solid state drives (SSDs) and is embedded in computers like Apple’s MacBook Air, PCM is nonvolatile — meaning it retains data after its power supply is shut down.

Unlike NAND flash, PCM memory does not require that existing data be marked for deletion prior to new data being written to it — a process known to as an erase-write cycle. Erase-write cycles slow NAND flash performance and, over time, wear it out, giving it a lifespan that ranges from 5,000 to 10,000 write cycles in consumer products and up to 100,000 cycles in enterprise-class products.

PCM can sustain up to 5 million write cycles, according to IBM.

“If you can write to flash 3,000 times, that will outlive most cell phones and MP3 players, but that’s certainly not good enough for the enterprise that does that in an hour,” said Christopher Sciacca, manager of communications for IBM Research in Zurich.

As organizations and consumers increasingly embrace cloud-computing models and services, ever more powerful and efficient, yet affordable storage technologies are needed, according to Haris Pozidis, manager of memory and probe technologies at IBM Research.

Pozidis said that for the past five months, teams of IBM scientists have been testing a multi-level cell (MLC) chip that’s capable of storing two and eventually three bits of data, indicating that it can achieve a level of reliability that is suitable for practical applications.

Besides applications for enterprises and in the cloud, PCM may also serve as an extension for DRAM .

While DRAM will continue to be used as the closest memory device to the CPU for the most active data, Pozidis said, PCM, with its greater capacity, can be used less frequently accessed data. “The PCM, which is much larger, acts as a repositor. If the data becomes hot again it will move back to the DRAM,” he said.

In another scenario, Pozidis said, the CPU can talk directly to the PCM, but it thinks its talking to the DRAM using a controller. “Again, the hot data speaks to DRAM and not so hot data speaks to the PCM,” he said.

DRAM is also expected to hit a technical wall in several years when it reaches lithography sizes of between 20-30 nanometers. One nanometer is roughly the size of four gold atoms.

A nascent technology, PCM is used today as a replacement for NOR, EEPROM, NVRAM memory that are currently manufactured by Micron Technology, Samsung, and South Korea’s Hynix Semiconductor.

Current technology is single-level cell (SLC) PCM, which only stores one bit per cell with limited capacity. For example, Samsung produces a 512Mbit PCM chip for its GT-E2550 GSM mobile phone. Micron’s Numonyx division makes a 128 Mbit PCM chip and isshipping product to several customers who use it in networking equipment, medical monitoring devices, and security cameras. .

Samsung’s PCM RAM chip

PCM uses electrical charges to change areas on a glassy material from crystalline to random or amorphous. The technique uses far less power than NAND flash to store data and it has data write rates up to 100 times faster because it does not first require existing data to be marked for deletion.

PCM leverages the resistance change that occurs in the material — an alloy of various elements — when it changes its phase from crystalline – featuring low resistance – to amorphous – featuring high resistance – to store data bits. In a PCM cell, where a phase-change material is deposited between a top and a bottom electrode, phase change can controllably be induced by applying voltage or current pulses of different strengths. These heat up the material, and when distinct temperature thresholds are reached cause the material to change from crystalline to amorphous or vice versa.

IBM scientists said they were able to address the bit error problem associated with MLC PCM memory by using an advanced modulation coding technique, which addresses the problem of short-term drift. Short-term drift is analogous to a problem in NAND flash memory where electrons leak through the thin walls of cells and create data read errors.

In NAND flash, the problem is addressed through the use of error correction code (ECC) in controller chips. But in PCM, data errors are not corrected, but avoided through the use of specialized code.

“With modulation codes you try to avoid the most probable errors. Modulation codes appear today in hard disk drives as well as optical drives such as Blu-ray discs,” Pozidis said. “We apply a voltage pulse based on the deviation from the desired level and then measure the resistance. If the desired level of resistance is not achieved, we apply another voltage pulse and measure again – until we achieve the exact level.”

IBM scientists achieved a worst-case write latency of about 10 microseconds, which represents a 100x performance increase over even the most advanced flash memory on the market today.

Pozidis said IBM is currently using PCM circuitry that is 90 nanometers in size, or about twice the width of today’s densest SLC PCM products. But that too will shrink over time.

IBM is not planning to produce consumer grade products out of PCM, Pozidis said. The main target for the technology is to license it to memory manufacturers, such as Toshiba and Samsung, and help them accelerate the production of the memory chips for enterprise applications.

Other researchers have been combining carbon nanotube technology with PCM to create chips that sip electricity and could extend the battery life of mobile devices to weeks.

Samsung announced that it has begun the mass production of a new 30nm-class 32GB memory module for green IT systems. This is the first time in the industry that mass production using 32GB modules and 30nm class chips has started. The 30nm modules use 4Gb DDR3 DRAM chips.

“With this module, Samsung has secured the highest level of product and solution competitiveness in the DRAM market for PC, server and mobile applications,” said Wanhoon Hong, executive vice president, memory sales & marketing, Samsung Electronics.

“We also plan to ship more energy-efficient 4Gb DDR3 DRAM based on 20nm-class* process technology in the second half of this year, which will significantly expand the rapidly growing market for green IT memory solutions. Moreover, we intend to keep delivering the greenest memory products with optimal performance for customers,” he added.
The new modules that Samsung is producing include 32GB RDIMM and 8GB SO-DIMM modules.

The RDIMM modules operate on 1.35V and can perform at up to 1866Mbps, which is 40% better than the 1333Mbps 40nm class modules operating at 1.5V. The new modules also consume 18% less power. The 8 GB SO-DIMM modules operate at up to 2133Mbps at 1.5V.

Samsung expects that almost 10% of its total DRAM shipments in 2012 will be 4Gb modules.

Shane McGlaun

Computer Memory, also known as RAM (Random Access Memory) is an integral part of your computer and plays an important role in the way your PC functions. In this guide, we will show you how you can test and identify bad memory modules on your PC.

If your PC is running on a single memory stick and emits endless beeps during boot-up, it is usually a sign of a completely damaged memory module. Identifying partially damaged RAM however can be difficult especially if your PC has multiple memory modules installed. But with a systematic approach and a series of memory tests, you can easily nail down the culprit memory module yourself!

Getting Started
Before proceeding further, let’s have a quick look at some of the most common symptoms of a bad memory module:

1. Computer freezes, crashes, or shows the Blue Screen of Death (BSOD) for no apparent reason.
2. Distorted graphics or interrupted media playback.
3. BSOD during software/operating system installations.
4. Computer crashes while you are playing games or running memory intensive applications such as Adobe® Photoshop®.

binodk

The most obvious factor on how to differ DDR3 from DDR2 memory is appearance. But, that is not as simple as it might seem. Unless you can find the specific reference on the memory stick, you will need to look at the key notch. Along the bottom of the memory stick, 240 pins insert into the motherboard. Among the pins is a notch. That notch prevents inserting the wrong type of memory into an incompatible slot. Looking from the top side, the notch on the DDR2 lies slightly to the right of the middle point of the memory stick. On the DDR3, the notch is slightly to the left of the middle.

How to Differ DDR3 from DDR2

DDR2 memory sticks do not fit into the slots for DDR3 sticks or vice versa. One reason why many manufacturers have been slow to adopt the newer DDR3 technology is because there is no backwards compatibility between the two. You cannot use a DDR3 when you do not have an appropriate slot in the motherboard for it. Some newer motherboards come with the ability for both types of memory to work. However, it is important to know how to differ DDR3 from DDR2 memory before you purchase it.

What else makes these memory sticks different? Transfer speed on DDR3 is double that of the DDR2. Transfer rates on DDR2 range from 400 to 800 Mbps. On the DDR3, the range is 800 to 1600 Mbps. The DDR2 has four internal banks of memory while the DDR3 has eight. The DDR2 does 4-bit prefetch and the DDR3 does 8-bit prefetch. The DDR2 uses more voltage than the DDR3 does. The DDR2 runs with 1.8V while DDR3 runs with 1.5V. DDR3 memory has a slightly higher latency than the DDR2. There are other technical differences between the two as well.

Currently, there is another significant way on how to differ DDR3 from DDR2 memory. The price is higher for the DDR3 memory sticks. Prices have continued to drop ever since the DDR3 came on the market a few years ago. However, the DDR2 sticks are still lower in price. But, newer motherboards are pushing the prices down on DDR3. The demand for the newer technology is starting to grow as higher memory requirements come into play with faster motherboards and chipsets. However, with the newer DDR4 technology planned for a 2012 release, the future of the DDR3 is still in question.

by Iftekhar Bhuiyan – Nov 28, 2011

Today Advanced Micro Devices’ (AMD) announced the retail availability of it’s first system memory module for the North American market. On a press release, AMD confirmed this news on their official web site. However, AMD released three different edition (Entertainment, Performance & Radeon) of their DDR3 memory module in partnership with Patriot Memory LLC and VisionTek Products, LLC.

amd memory

These memory modules will be available from major online retailers that includes Amazon.com, Bestbuy, Tiger Direct, Newegg, Micro Center, NCIX, VIP Computers (UK) and many others along with their chain stores throughout North America.

AMD DDR3 Memory ModuleAMD stated that, it is collaborating with memory module makers to create the AMD Memory branded products from components, which are qualified to meet certain specifications. They are testing and certifying these memory to make sure that the end-users can be assured of compatibility with AMD platforms.

While talking about the new Partnership with AMD, Paul Jones, CEO of Patriot Memory said, “Patriot Memory will bring over two decades of experience and expertise into this ecosystem, …Our proven ability to deliver the best technology at the most competitive prices will help pave the way to success for this memory line.”

Initially, these memory modules will be available in 2GB, 4GB & 8GB sizes based on the Price point & speeds. To be little more specific, the entertainment category module will feature 1333 MHz & 1600 MHz speed RAM which is designed for home theater PC application. However, the performance category module will support up to 1600 MHz of RAM speed with low latency. To enable the maximum performance  Radeon edition will run at 1866 MHz speed.

(Source: AMD)