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In this next example, both the NcbZcLightExtPan and the SrbZcSwitchExtPan projects will use the extended PAN ID of 0x1122334455667788. The PAN ID will be set to 0xffff so that the NcbZcLightExtPan will form a random PAN ID and the SrbZcSwitchExtPan will find it. The example will look very similar from a user perspective to the previous one, but the over-the-air mechanism used is quite different (see Figure 4.15).

74LVC157APW/AUJ_NXP USA Inc._Logic - Signal Switches, Multiplexers, Decoders

In this next example, both the NcbZcLightExtPan and the SrbZcSwitchExtPan projects will use the extended PAN ID of 0x1122334455667788. The PAN ID will be set to 0xffff so that the NcbZcLightExtPan will form a random PAN ID and the SrbZcSwitchExtPan will find it. The example will look very similar from a user perspective to the previous one, but the over-the-air mechanism used is quite different (see Figure 4.15).

Figure 3: Graphical representation of a basic PCM storage element. As shown on the left, a layer of chalcogenide is sandwiched between a top electrode and a bottom electrode. A resistive heating element extends from the bottom electrode and contacts a layer of the chalcogenide material. Current passed through the heater induces the phase change through Joule heating. At right is the actual implementation of the concept, showing an amorphous bit formed in a layer of polycrystalline chalcogenide. Because of the change in reflectivity, the amorphous bit appears as a mushroom cap shaped structure in the layer of polycrystalline chalcogenide.

Looking ahead at phase-change memory A state of the art PCM technology/product is shown in Figure 4 illustrating a 1-Gbit 45-nm vehicle. PCM is on a trajectory to converge with DRAM for lithography capability with the next generation of 32nm, due in the next few years.

74LVC157APW/AUJ_NXP USA Inc._Logic - Signal Switches, Multiplexers, Decoders

Figure 4: 1-Gbit, 45-nm demonstration vehicle

PCM will initially be used in high performance memory sub systems to achieve Solid State drive performance and reliability that is unachievable with NAND and at power consumption levels (and nonvolatility) that can not be achieved with RAM. As system software evolves to fully exploit the capabilities of PCM, it will be able to move from an I/O drive” based usage model to a directly memory mapped main memory” based usage model, further increasing its performance value. This migration is shown in Figure 5 . As the PCM cost structure continues to drop through scaling at a faster rate than DRAM, its opportunities to displace more DRAM and NAND will increase, although it is not envisioned to directly challenge NAND on a cost basis.

74LVC157APW/AUJ_NXP USA Inc._Logic - Signal Switches, Multiplexers, Decoders

Figure 5: PCM in the memory hierarchy

Looking further into the future, a derivative of PCM, called PCMS (Stacked PCM), which enables the stacking of several layers of PCM memory arrays on top of each other promises to deliver cost lower than NAND combined with the scalability of PCM. PCMS, which is in research today, provides a natural evolution of the phase-change memory concept should the research be successful.

74LVC157APW/AUJ_NXP USA Inc._Logic - Signal Switches, Multiplexers, Decoders

Phase-change memory–the next generation of nonvolatile memory, ready today The road for PCM has been a long one, starting with the basic concept in the 1950s, evolving through early feasibility demonstration in the 1970s, moving on to a resurgence of activity in the 2000s, resulting in products with the potential to provide breakthrough capabilities in the 2010s. The evolution of the semiconductor industry has enabled the manufacture of structures small enough to exploit the unique storage capabilities of PCM while, in parallel, volume usage of PCM materials for optical memories has driven the rapid learning of the material properties and physics. This trend combined with the 10 years of development by Intel and ST moving to Micron now has PCM ready for prime time” as a next generation nonvolatile memory at a time when traditional electron storage memories are beginning to encounter difficulties. Expect to see PCM leverage its unique capabilities as a storage class memory” to find a new position in the memory hierarchy.

Greg Atwood is a senior fellow at Micron Technology, Inc. He received a M.S. degree in physics from Purdue University in 1979, joining Intel Corporation in the same year. At Intel, he worked on numerous technology development programs including Logic, SRAM, EPROM, E2PROM, flash, Multi-Level Flash, and phase-change memory. In 2008, he joined Numonyx B.V. as their first Senior Fellow with a focus on phase-change products. Numonyx was acquired by Micron in May 2010. Since 2002, Greg has been primarily focused on Phase Change Memory development and bringing the technology to market. He is the author of numerous articles and papers and holds more than 40 patents.

Dispersed data sourcesIndustry leading companies have begun to go beyond functional simulation and embrace the use of formal verification, emulation and acceleration to drive greater verification success for greater quality and schedule predictability. In addition, multi-vendor and multiple methodologies are now a norm rather than an exception. As a result, important information pertaining to the status and quality of the project is spread out.

– Verification using various methodologies Functional, formal and emulation based methodologies have different formats and schemes to report information about project progress.

Verification methodologies constantly evolve to keep pace with design complexity. New techniques and languages are constantly being evolved. Leading companies often have various teams using different methodologies with different degree of maturity.

– Variety of vendors with their specific formats The trend to use multi-vendor solutions is growing in the industry due to two reasons: a. customers want to maintain leverage with their EDA tool supplier and b. As the technology is maturing the tool performance and functionality are becoming comparable from various vendors.

Although UCIS (Universal Coverage Interoperability Standard) is working to ameliorate the problem of different vendors using their own database and reporting formats, however, as of this writing it’s still not a released work.

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