Download or read book Coding for Flash Memories written by Eitan Yaakobi and published by . This book was released on 2011 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flash memories are, by far, the most important type of non-volatile memory in use today. They are employed widely in mobile, embedded, and mass-storage applications, and the growth in this sector continues at a staggering pace. Moreover, since flash memories do not suffer from the mechanical limitations of magnetic disk drives, solid-state drives have the potential to upstage the magnetic recording industry in the foreseeable future. The research goal of this dissertation is the discovery of new coding theory methods that supports efficient design of flash memories. Flash memory is comprised of blocks of cells, wherein each cell can take on q>̲ 2 levels. While increasing the cell level is easy, reducing its level can be accomplished only by erasing an entire block. Such block erasures are not only time-consuming, but also degrade the memory lifetime. Our main contribution in this research is the design of rewriting codes that maximize the number of times that information can be written prior to incurring a block erasure. Examples of such coding schemes are flash/floating codes and buffer codes, introduced by Jiang and Bruck et al. in 2007, and WOM-codes that were presented by Rivest and Shamir almost three decades ago. The overall goal in these codes is to maximize the amount of information written to a fixed number of cells in a fixed number of writes. Furthermore, the design of error-correcting codes in flash memories is extensively studied. It is shown how to modify WOM-codes to support an error-correction capability. Motivated by the asymmetry of the error behavior of flash memories and the work by Cassuto et al., a coding scheme to correct asymmetric errors is presented. An extensive empirical database of errors was used to develop a comprehensive understanding of the error behavior as well as to design specific error-correcting codes for flash memories. This research on flash memories is expanded to other directions. Wear leveling techniques are widely used in flash memories in order to reduce and balance block erasures. It is shown that coding schemes to be used in these techniques can significantly reduce the number block erasures incurred during data movement. Also, the design of parallel cell programming algorithms is studied for the specific constraints and behavior of flash cells.
Download or read book Channel and Source Coding for Non Volatile Flash Memories written by Mohammed Rajab and published by Springer Nature. This book was released on 2020-01-02 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mohammed Rajab proposes different technologies like the error correction coding (ECC), sources coding and offset calibration that aim to improve the reliability of the NAND flash memory with low implementation costs for industrial application. The author examines different ECC schemes based on concatenated codes like generalized concatenated codes (GCC) which are applicable for NAND flash memories by using the hard and soft input decoding. Furthermore, different data compression schemes are examined in order to reduce the write amplification effect and also to improve the error correct capability of the ECC by combining both schemes.
Download or read book Error Correction Codes for Non Volatile Memories written by Rino Micheloni and published by Springer Science & Business Media. This book was released on 2008-06-03 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nowadays it is hard to find an electronic device which does not use codes: for example, we listen to music via heavily encoded audio CD's and we watch movies via encoded DVD's. There is at least one area where the use of encoding/decoding is not so developed, yet: Flash non-volatile memories. Flash memory high-density, low power, cost effectiveness, and scalable design make it an ideal choice to fuel the explosion of multimedia products, like USB keys, MP3 players, digital cameras and solid-state disk. In ECC for Non-Volatile Memories the authors expose the basics of coding theory needed to understand the application to memories, as well as the relevant design topics, with reference to both NOR and NAND Flash architectures. A collection of software routines is also included for better understanding. The authors form a research group (now at Qimonda) which is the typical example of a fruitful collaboration between mathematicians and engineers.
Download or read book Coding Techniques to Extend the Lifetime of Flash Memories written by Yi Liu and published by . This book was released on 2020 with total page 185 pages. Available in PDF, EPUB and Kindle. Book excerpt: NAND flash memory has become a widely used data storage technology. It uses rectangular arrays, or blocks of floating-gate transistors (commonly referred to as cells) to store information. The flash memory cells gradually wear out with repeated writing and erasing, referred to as program/erase (P/E) cycling, but the damage caused by P/E cycling is dependent on the programmed cell level. For example, in SLC flash memory, each cell has two different states, erased and programmed, represented by 1 and 0, respectively. Storing 1 in a cell causes less damage, or wear, than storing 0. More generally, in multilevel flash memories, the cell wear is an increasing function of the programmed cell level. The main research goal of this dissertation is to design new coding techniques that can extend the lifetime of flahs [flash] memories. The damage caused by programming the cell is usually modeled as a cost, and increasing the lifetime of flash memories can be converted to the problem of encoding information for use on channels with a cost constraint. This type of code is often referred to as a shaping code. Therefore in this dissertation we study rate-constrained shaping codes for noiseless costly channels. We systematically investigate the fundamental performance limits of fixed-to-variable length shaping codes from a rate and distribution perspective for a memoryless channel. Then, we study a recently proposed rate-1 direct shaping code and study its error propagation property. In addition, we consider shaping codes for finite-state noiseless costly channels. One observation from the above analysis is that an optimal shaping code for a memoryless channel generates a codeword sequence that approximates an i.i.d. process, and an optimal shaping code for a finite-state channel generates a codeword sequence that approximates a stationary Markov process. In this dissertation, we study the connection between shaping codes and distribution matching codes that map a sequence of i.i.d. source symbols into an output sequence that approximates an i.i.d. or a stationary Markov process. In the flash memory device, the bit error count (BEC) behavior varies significantly among pages. Therefore we propose a bad page detector, which predicts whether a page will become a "bad" page in the near future based on its current and previous BEC information. Two machine learning algorithms, based upon time-dependent neural network and long-short term memory architectures, are used to design the detector.
Download or read book Flash Memories written by Paulo Cappelletti and published by Springer. This book was released on 2014-02-23 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt: A Flash memory is a Non Volatile Memory (NVM) whose "unit cells" are fabricated in CMOS technology and programmed and erased electrically. In 1971, Frohman-Bentchkowsky developed a folating polysilicon gate tran sistor [1, 2], in which hot electrons were injected in the floating gate and removed by either Ultra-Violet (UV) internal photoemission or by Fowler Nordheim tunneling. This is the "unit cell" of EPROM (Electrically Pro grammable Read Only Memory), which, consisting of a single transistor, can be very densely integrated. EPROM memories are electrically programmed and erased by UV exposure for 20-30 mins. In the late 1970s, there have been many efforts to develop an electrically erasable EPROM, which resulted in EEPROMs (Electrically Erasable Programmable ROMs). EEPROMs use hot electron tunneling for program and Fowler-Nordheim tunneling for erase. The EEPROM cell consists of two transistors and a tunnel oxide, thus it is two or three times the size of an EPROM. Successively, the combination of hot carrier programming and tunnel erase was rediscovered to achieve a single transistor EEPROM, called Flash EEPROM. The first cell based on this concept has been presented in 1979 [3]; the first commercial product, a 256K memory chip, has been presented by Toshiba in 1984 [4]. The market did not take off until this technology was proven to be reliable and manufacturable [5].
Download or read book Flash Memories written by Igor Stievano and published by BoD – Books on Demand. This book was released on 2011-09-06 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flash memories and memory systems are key resources for the development of electronic products implementing converging technologies or exploiting solid-state memory disks. This book illustrates state-of-the-art technologies and research studies on Flash memories. Topics in modeling, design, programming, and materials for memories are covered along with real application examples.
Download or read book Inside NAND Flash Memories written by Rino Micheloni and published by Springer Science & Business Media. This book was released on 2010-07-27 with total page 582 pages. Available in PDF, EPUB and Kindle. Book excerpt: Digital photography, MP3, digital video, etc. make extensive use of NAND-based Flash cards as storage media. To realize how much NAND Flash memories pervade every aspect of our life, just imagine how our recent habits would change if the NAND memories suddenly disappeared. To take a picture it would be necessary to find a film (as well as a traditional camera...), disks or even magnetic tapes would be used to record a video or to listen a song, and a cellular phone would return to be a simple mean of communication rather than a multimedia console. The development of NAND Flash memories will not be set down on the mere evolution of personal entertainment systems since a new killer application can trigger a further success: the replacement of Hard Disk Drives (HDDs) with Solid State Drives (SSDs). SSD is made up by a microcontroller and several NANDs. As NAND is the technology driver for IC circuits, Flash designers and technologists have to deal with a lot of challenges. Therefore, SSD (system) developers must understand Flash technology in order to exploit its benefits and countermeasure its weaknesses. Inside NAND Flash Memories is a comprehensive guide of the NAND world: from circuits design (analog and digital) to Flash reliability (including radiation effects), from testing issues to high-performance (DDR) interface, from error correction codes to NAND applications like Flash cards and SSDs.
Download or read book Error Characterization Channel Modeling and Coding for Flash Memories written by Veeresh Taranalli and published by . This book was released on 2017 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt: NAND Flash memories have become a widely used non-volatile data storage technology and their application areas are expected to grow in the future with the advent of cloud computing, big data and the internet-of-things. This has led to aggressive scaling down of the NAND flash memory cell feature sizes and also increased adoption of flash memories with multiple cell levels to increase the data storage density. These factors have adversely affected the reliability of flash memories. In this dissertation, our main goal is to perform detailed characterization of the errors that occur in multi-level cell (MLC) flash memories and develop novel mathematical channel models that better reflect the measured error characteristics than do current models. The channel models thus developed are applied to error correcting code (ECC) frame error rate (FER) performance estimation in MLC flash memories and to estimating the flash memory channel capacity as represented by the channel models. We also utilize the characterization of inter-cell interference (ICI) errors to evaluate the performance of constrained coding schemes that mitigate ICI and improve the reliability of flash memories. In Chapter 5, which is self-contained, we propose and study modifications to adaptive linear programming decoding techniques applied to decoding polar codes. We also propose a reduced complexity representation of the polar code sparse factor graph, resulting in time complexity improvements in the adaptive LP decoder.
Download or read book Design Recipes for FPGAs Using Verilog and VHDL written by Peter Wilson and published by Elsevier. This book was released on 2011-02-24 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: Design Recipes for FPGAs: Using Verilog and VHDL provides a rich toolbox of design techniques and templates to solve practical, every-day problems using FPGAs. Using a modular structure, the book gives ‘easy-to-find’ design techniques and templates at all levels, together with functional code. Written in an informal and ‘easy-to-grasp’ style, it goes beyond the principles of FPGA s and hardware description languages to actually demonstrate how specific designs can be synthesized, simulated and downloaded onto an FPGA. This book's ‘easy-to-find’ structure begins with a design application to demonstrate the key building blocks of FPGA design and how to connect them, enabling the experienced FPGA designer to quickly select the right design for their application, while providing the less experienced a ‘road map’ to solving their specific design problem. The book also provides advanced techniques to create ‘real world’ designs that fit the device required and which are fast and reliable to implement. This text will appeal to FPGA designers of all levels of experience. It is also an ideal resource for embedded system development engineers, hardware and software engineers, and undergraduates and postgraduates studying an embedded system which focuses on FPGA design. A rich toolbox of practical FGPA design techniques at an engineer's finger tips Easy-to-find structure that allows the engineer to quickly locate the information to solve their FGPA design problem, and obtain the level of detail and understanding needed
Download or read book Coding for Distributed Storage and Flash Memories written by Pengfei Huang and published by . This book was released on 2018 with total page 169 pages. Available in PDF, EPUB and Kindle. Book excerpt: A modern large-scale storage system usually consists of a number of distributed storage nodes, each of which is made up of many storage devices, like flash memory chips. To maintain the data integrity in the system, two independent layers of data protection mechanisms are deployed. At the system level, erasure codes, e.g., maximum distance separable (MDS) codes, are used across a set of storage nodes. At the device level, error-correcting codes (ECCs), e.g., Bose-Chaudhuri-Hocquenghem (BCH) codes, are employed in each flash memory chip. The main research goal of this dissertation is to design new erasure codes for distributed storage and new ECCs for flash memories. The first part of this dissertation is devoted to studying a new class of erasure codes called locally repairable codes (LRCs) for distributed storage. We focus on LRCs over small fields; in particular, the binary field. We investigate the locality of classical binary linear codes, e.g., BCH codes and Reed-Muller codes, and their modified versions. Then, we derive bounds for LRCs with availability and present several new code constructions for binary LRCs. In addition, we study erasure codes that can locally correct multiple erasures. Such codes are referred to as multi-erasure locally repairable codes (ME-LRCs). Our constructions based on generalized tensor product codes generate several families of optimal ME-LRCs over small fields. The second part of this dissertation aims to construct new ECCs and analyze the fundamental performance limits for flash memories. We propose a general framework for constructing rate-compatible ECCs which are capable of adapting different error-correcting capabilities to the corresponding bit error rates at different program/erase (P/E) cycles. Next, we present a new family of shared-redundancy ECCs called ladder codes. Using ladder codes, multiple codewords from good and bad pages in a flash memory block can share some common redundancy. Finally, based on the channel models obtained from empirical data, the performance of multilevel flash memories is studied by using multi-user information theory. The results provide qualitative insight into effective coding solutions.
Download or read book Flash Memories written by Paulo Cappelletti and published by Springer Science & Business Media. This book was released on 2013-11-27 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt: A Flash memory is a Non Volatile Memory (NVM) whose "unit cells" are fabricated in CMOS technology and programmed and erased electrically. In 1971, Frohman-Bentchkowsky developed a folating polysilicon gate tran sistor [1, 2], in which hot electrons were injected in the floating gate and removed by either Ultra-Violet (UV) internal photoemission or by Fowler Nordheim tunneling. This is the "unit cell" of EPROM (Electrically Pro grammable Read Only Memory), which, consisting of a single transistor, can be very densely integrated. EPROM memories are electrically programmed and erased by UV exposure for 20-30 mins. In the late 1970s, there have been many efforts to develop an electrically erasable EPROM, which resulted in EEPROMs (Electrically Erasable Programmable ROMs). EEPROMs use hot electron tunneling for program and Fowler-Nordheim tunneling for erase. The EEPROM cell consists of two transistors and a tunnel oxide, thus it is two or three times the size of an EPROM. Successively, the combination of hot carrier programming and tunnel erase was rediscovered to achieve a single transistor EEPROM, called Flash EEPROM. The first cell based on this concept has been presented in 1979 [3]; the first commercial product, a 256K memory chip, has been presented by Toshiba in 1984 [4]. The market did not take off until this technology was proven to be reliable and manufacturable [5].
Download or read book Nonvolatile Memory Technologies with Emphasis on Flash written by Joe Brewer and published by John Wiley & Sons. This book was released on 2011-09-23 with total page 766 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presented here is an all-inclusive treatment of Flash technology, including Flash memory chips, Flash embedded in logic, binary cell Flash, and multilevel cell Flash. The book begins with a tutorial of elementary concepts to orient readers who are less familiar with the subject. Next, it covers all aspects and variations of Flash technology at a mature engineering level: basic device structures, principles of operation, related process technologies, circuit design, overall design tradeoffs, device testing, reliability, and applications.
Download or read book 3D Flash Memories written by Rino Micheloni and published by Springer. This book was released on 2016-05-26 with total page 391 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book walks the reader through the next step in the evolution of NAND flash memory technology, namely the development of 3D flash memories, in which multiple layers of memory cells are grown within the same piece of silicon. It describes their working principles, device architectures, fabrication techniques and practical implementations, and highlights why 3D flash is a brand new technology. After reviewing market trends for both NAND and solid state drives (SSDs), the book digs into the details of the flash memory cell itself, covering both floating gate and emerging charge trap technologies. There is a plethora of different materials and vertical integration schemes out there. New memory cells, new materials, new architectures (3D Stacked, BiCS and P-BiCS, 3D FG, 3D VG, 3D advanced architectures); basically, each NAND manufacturer has its own solution. Chapter 3 to chapter 7 offer a broad overview of how 3D can materialize. The 3D wave is impacting emerging memories as well and chapter 8 covers 3D RRAM (resistive RAM) crosspoint arrays. Visualizing 3D structures can be a challenge for the human brain: this is way all these chapters contain a lot of bird’s-eye views and cross sections along the 3 axes. The second part of the book is devoted to other important aspects, such as advanced packaging technology (i.e. TSV in chapter 9) and error correction codes, which have been leveraged to improve flash reliability for decades. Chapter 10 describes the evolution from legacy BCH to the most recent LDPC codes, while chapter 11 deals with some of the most recent advancements in the ECC field. Last but not least, chapter 12 looks at 3D flash memories from a system perspective. Is 14nm the last step for planar cells? Can 100 layers be integrated within the same piece of silicon? Is 4 bit/cell possible with 3D? Will 3D be reliable enough for enterprise and datacenter applications? These are some of the questions that this book helps answering by providing insights into 3D flash memory design, process technology and applications.
Download or read book Coding Techniques for Error Correction and Rewriting in Flash Memories written by Shoeb Ahmed Mohammed and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Flash memories have become the main type of non-volatile memories. They are widely used in mobile, embedded and mass-storage devices. Flash memories store data in floating-gate cells, where the amount of charge stored in cells 0́3 called cell levels 0́3 is used to represent data. To reduce the level of any cell, a whole cell block (about 106 cells) must be erased together and then reprogrammed. This operation, called block erasure, is very costly and brings significant challenges to cell programming and rewriting of data. To address these challenges, rank modulation and rewriting codes have been proposed for reliably storing and modifying data. However, for these new schemes, many problems still remain open. In this work, we study error-correcting rank-modulation codes and rewriting codes for flash memories. For the rank modulation scheme, we study a family of one- error-correcting codes, and present efficient encoding and decoding algorithms. For rewriting, we study a family of linear write-once memory (WOM) codes, and present an effective algorithm for rewriting using the codes. We analyze the performance of our solutions for both schemes.
Download or read book Channel Coding for Flash Memories written by Jens Spinner and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Programming of Flash Memory written by and published by . This book was released on 2000 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy aware Error Control Coding for Flash Memories and Low power Error Tolerant Data path written by Veera Papirla and published by . This book was released on 2009 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt:
