Foreword: This high-level whitepaper from Datalight examines the role of NAND flash memory in embedded devices, and how that role is likely to evolve. The article examines emerging hardware and software trends driven by the explosive growth of high-capacity consumer electronic devices.

From MP3 players to picture phones to portable computer drives, millions of people now carry around devices capable of storing large amounts of data, and the majority of these devices use NAND flash memory.

It is no wonder NAND flash memory has become the preferred nonvolatile data format for portable consumer electronic devices. Features such as high density, low cost, fast write times, and a long re-write life expectancy make NAND especially well suited for media applications in which large files of sequential data need to be loaded into memory quickly and repeatedly.

Explosive growth in the use of high-capacity consumer electronic devices has not only created a growing demand for NAND flash memory, it is also reshaping the ways NAND will be used in a wide variety of embedded applications. The following trends have already begun and are expected to continue.

Growing Market Demand

The demand for NAND memory chips has increased rapidly and is expected to continue to grow in years to come. It is predicted that 2005 is the year NAND overtakes NOR as the larger flash memory revenue market.

Penetrating NOR Markets

NOR flash memory has traditionally been used to store relatively small amounts of executable code for embedded computing devices such as PDAs and cell phones. NOR is well suited for such computational applications due to its fast read times, random access, and execute-in-place capabilities. A traditionally strong market for NOR memory has been mobile phones. But the need for high density, low-cost memory has led to greater use of NAND memory in newer high performance phones that support features such as built-in cameras and streaming media.

Blended Hardware Solutions

For many devices it is not simply a choice between NAND and NOR memory. An application that needs both fast code execution as well as large data storage needs more than just NAND memory. Either code stored in NAND memory needs to be copied into RAM for execution, or there needs to be NOR memory for code storage and execution. Some OEMs develop their own custom memory combinations of NAND with NOR and/or RAM. Others look to semiconductor manufacturers to provide solutions, such as Samsung's OneNAND product which combines a NAND array with a NOR interface in one package. In the future, look for more single-component solutions designed for a wider variety of devices.

Memory Management Software

File systems typically used by operating systems by default, such as FAT, often do not provide the level of performance and reliability required by new high-capacity devices. OEMs find it increasingly valuable to write or license dedicated memory management software for their embedded devices. Such software can not only prevent data loss caused by power interruptions or bad memory blocks, it can also improve the performance and extend the life of NAND media. The best memory management software will be multithreaded to allow high priority requests to interrupt background operations such as data compaction. The importance of memory management software will increase in the future with the growing size of NAND flash arrays and the increasingly complex ways that embedded devices use them.

Summary

The market demand for ever-larger NAND flash arrays will continue to be driven primarily by portable consumer electronic devices that promise to store increasing amounts of data, especially video and audio information. As expectations for storage capacity filter down to a wider range of devices, more embedded development projects will be facing the complexities of integrating multiple memory types with larger NAND arrays. At first many OEMs will design and implement solutions in-house, but the trend will be toward blended hardware solutions from the semiconductor manufacturers supported by highly sophisticated memory management software products from third parties.

Copyright (C) 2005 Datalight Inc. Reproduced by LinuxDevices.com with permission.

 
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