Memories of light

The author briefly discusses both optical disc and magnetic media for recording data pointing out that they are complementary to each other. The author then describes the technology involved in write-once optical media and erasable optical recording     

Products for tomorrow

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Surface-Acoustic-Wave Random-Access Memories

An acoustic tapped-delay line (TDL) undermultiplexer control exhibits random-access-memory (RAM) capability; programmable time compression/expansion is achieved by controlling the difference between tap switching interval and intertap delay. A serial-in/parallel-out configuration can perform spectral compression of high input bandwidths, while requiring a single sampling operation to be performed, at the output data rate; dual properties are demonstrated by a parallel-in/serial-out organized RAM used for time compression. A new powerful N-phase configuration is discussed, which allows the intrinsic switching capability of multiplexers employed to be increased by N, while offering high dynamic range capability. The basic operation of the new technique is discussed, some theoretical aspects are investigated, and various effective configurations are described. In particular, the natural format of the time contracted/segmented output from a nonlinear convolver, asynchronously operated, is recovered; a clock-programmable bandpass filter is demonstrated, based on complementary time compression expansion. Extension to read-only memory (ROM) is briefly outlighted, with reference to frequency synthesis. Finally, processing of signals in basel and format is demonstrated using acoustic TDL's, via a simple modulation technique, which increases flexibility and the potential attraction of the new technique.     

一台DC，两种回忆

在数字化不断发展的今天，人们有更多的理由去关注生活本身的品质。如同我们用手中的相机去记录下家庭温馨生活的点滴，在拍摄的过程当中为家庭成员们带来更多的乐趣，彼此之间的关系更加亲密，而且可以让大家以后再回过头来，一起回忆过往的甜蜜，感悟与感恩生活的美好。     

几种新型非易失性存储器

本文简单介绍了铁电存储器、磁性随机存储器和相变存储器这三种比较有发展潜力存储器的原理、研究进展及存在的问题等.     

Optical Ring-Resonator Random-Access Memories

This paper examines the properties of optical resonator memory cells, in which a data bit is stored in a high- optical resonator. It is shown that resonator-based optical memories are ultimately limited by losses in the resonators, by the extinction ratio and chirp of the variable coupling medium that injects and extracts data into and out of the resonators, and by chirp on the input signal. Using a simple analytical model and accurate field-based simulations, we analyze the performance of a ring-resonator optical memory cell and compare this with the performance of slow light delay line buffer memories and complementary metal-oxide-semiconductor embedded dynamic random-access memory.     

半导体存储器走出阴霾,春光可待

半导体存储器一般是配置在ＰＣ内部的一种半导体芯 片,用于存储处理器运行时所需的指令和信息。它和硬盘的不同点之一,是大多半导体存储器易于挥发而丢失信息,需要电源不断充电以保持数据。它在半导体产品中占有重要地位,据世界半导体贸易统计协会（ＷＳＴＳ）统计,１９９９年是仅次于微芯片的第二大产品市场。 １．ＤＲＡＭ 需求强势,价格反弹 １９９５年存储器曾占ＩＣ市场份额的４２％,１９９９年降到２４．８％,２０００年预计可回升到２８．１％,而ＤＲＡＭ又占整个存储器市场的６０～７０％,因此,ＤＲＡＭ的兴衰对整个存储…     

Renewable energy today and tomorrow

Energy is essential to our society to ensure our quality of life and to underpin all other elements of our economy. Renewable energy technologies offer the promise of clean, abundant energy gathered from self-renewing resources such as the sun, wind, earth, and plants. Virtually all regions of the United States and the world have renewable resources of one type or another. Renewable resources currently account for about 10% of the energy consumed in the United States, most of this is from hydropower and traditional biomass sources. Wind, solar biomass, and geothermal technologies are cost-effective today in an increasing number of markets, and are making important steps to broader commercialization. Each of the renewable energy technologies is in a different stage of research, development, and commercialization, and all have differences in current and future expected costs, current industrial base, resource availability, and potential impact on greenhouse gas emissions. The technical status, cost, and applications of major renewable energy technologies and implications for increased adoption of renewables will be reviewed     

Universal multimedia experiences for tomorrow

The previous decade has seen a variety of trends and developments in the area of communications and thus multimedia access. While individual, isolated developments produced small advances on the status quo, their combination and cross-fertilization resulted in today's complex but exciting landscape. In particular, we are beginning to see delivery of all types of data for all types of users in all types of conditions. This article discusses the current status of universal multimedia access (UMA) technologies and investigates future directions in this area. Key developments and trends from the last few years have set the scene for ubiquitous multimedia consumption. In summary, these are: wireless communications and mobility; standardized multimedia content; interactive versus passive consumption; and the Internet and the World Wide Web (WWW).     

未来内存应用大透析

问题提出 在Ｉｎｔｅｌ开发者论坛和ＰＬＡＴＦＯＲＭ ２０００都已结束后,我们是否可以对２００１年内存发展趋势作一个预测呢？现在这个问题变得比以前更加令人捉摸不透。这里有两大阵营：ＩＮＴＥＬ这边坚信ＲＤＲＡＭ（ＲＡＭＢＵＳ）,而另一边则推崇ＤＤＲ和ＰＣ１３３。两家都在吹捧各自的性能与价格。那么内存市场是否会出现分裂呢？我们希望从技术角度分析一下目前的局势。 要找到上述问题的答案,我们有必要来审视一下整个“电子行业”,而不仅仅是ＰＣ这一部分。实际上,存储器的未来并不象我们理解的那样只局限与ＰＣ行业, Ｍ…     

“搜索”出博客的明天

百度公司的个人博客服务——“百度空间”已于7月13日正式上线。继新浪、雅虎等国内外知名互联网企业纷纷加盟“博客军团”后，百度也正式涉足博客领域，并将凭借“博客＋搜索”的新概念掀起新一轮的竞争热潮。[编者按]     

短消息业务的今日和明天

短消息业务（SMS）在移动通信和互联网上的业务量增长迅速，2001年全球共发送了2500亿条短消息，而中国移动的短信业务收入达15.9亿元，不过，如果以一种前瞻性的技术眼光去审视这股热潮，就不难发现移动消息业务的发展趋势：随着时间的推移，简单文本在移动通信中将会变得越来越少，人们会越来越注重视觉效果，文本消息将逐步向图标、图片消息，再向视频及电影消息演进。这些全新的业务和应用将不再是简单的SMS力所能及的，届时，EMS（增强消息业务）和MMS（多媒体消息业务）将登台亮相，大显身手。移动消息业务将沿着从SMS到EMS再…     

Reliability of Single-Error Correction Protected Memories

Reliability is a critical factor for systems operating in radiation environments. Among the different components in a system, memories are one of the parts most sensitive to soft errors due to their relatively large area. Due to their large cost, traditional techniques like Triple Modular Redundancy are not used to protect memories. A typical approach is to apply Error Correction Codes to correct single errors, and detect double errors. This type of codes, for example those based on Hamming, provides an initial level of protection. Detected single errors are usually corrected using scrubbing, by which the memory positions are periodically re-written after a fixed (deterministic scrubbing), or variable period (probabilistic scrubbing). These traditional models usually offer good results when calculating the reliability of memories (e.g. through the Mean Time To Failure). However, there are some particularities that are not modeled through these approaches, to the best of our knowledge. One of these particularities is how double errors are handled. In a traditional approach, two errors in the same word produce always a system failure (only single errors can be corrected). However, if the two (or more) errors affect the same bit, either the second one reinforces the first one (keeping just a single error), or corrects it. In both scenarios, the resulting situation does not trigger a system failure, which has a direct impact on the reliability of the memory. In this paper, traditional reliability models are refined to handle the mentioned scenarios, which produces a more precise analysis in the calculation of mean time to failure for memory systems.      

Rank Modulation for Flash Memories

We explore a novel data representation scheme for multilevel flash memory cells, in which a set of $n$ cells stores information in the permutation induced by the different charge levels of the individual cells. The only allowed charge-placement mechanism is a “push-to-the-top” operation, which takes a single cell of the set and makes it the top-charged cell. The resulting scheme eliminates the need for discrete cell levels, as well as overshoot errors, when programming cells.      

铁电随机存储器的研究进展

铁电薄膜与半导体集成技术相结合而发展起来的铁电存储器．以其高密度、高速度、非易失性及抗辐射性而大大优于目前任何一种半导体存储器。该文介绍了铁电存储器的存储原理、特点、基本存储单元、研究进展、应用及存在的问题，并指出1T结构的铁电随机存储器(FRAM)将会成为下一代随机存储器。