存储器的文献综述

存储器的发展史范文
存储器的概念和应用始于最早的计算机系统，因为它可以暂存数据，
从而使计算机系统能够更高效率地运行。

它一般可以分为RAM（随机存取
存储器）和ROM（只读存储器）两类。

随着计算机技术的发展，存储器也
在不断地发展和进步，分别出现了各种功能性不同的新型存储器。

20世纪五六十年代，随着计算机技术的快速发展，计算机存储器也
有了显著进步。

最早的存储系统是由磁弹簧，开关，槽，插槽和扩展的读
写头组成。

磁弹簧存储系统是由磁性材料来存储数据的，其存储容量较小，但读写速度较快，能够满足当时基本的计算机系统的需求。

1960年代，随着集成电路技术的出现，有了更多的改进，计算机存
储器的技术也取得了长足的进步。

在这一时期，一种称为“磁头”的新类
型存储器出现了，它使用的是磁性磁道存储数据。

磁头存储器具有较大的
容量，速度快，便于操作等特点，被广泛应用在主机和计算机系统中。

1970年，随着大规模集成电路的发展，计算机存储器又有了新的技
术变革。

在这一时期，由半导体技术推动的，“半导体存储器”应运而生。

毕业设计（论文）文献综述题目Oracle存储过程原理及应用专业计算机科学与技术班级07级计科1 班学生宋龙指导教师王家伟重庆交通大学2011年ORACLE存储过程原理及应用摘要计算机技术的飞速发展，推动了整个社会的信息化进程，促进了信息技术的进步，催生了量的信息系统，尤其是各种管理软件。

而管理软件离不开对大量数据的处理，这就要依赖于数据库管理系统。

Oracle 是当前世界上使用最为广泛的数据库管理系统之一，由于Oracle 拥有强大的数据管理能力和较好的数据保密性，以及出众的技术优势。

Oracle 得到了大规模的应用，它经常作为大型管理软件的后台数据库。

程序可以通过相应的软件接口对数据库进行操作，因为大型系统的业务规则一般都比较复杂，需要进行多个库表的操作，逻辑比较复杂，如果单纯使用SQL 语句进行数据库操作，应用程序代码会非常冗长，网络传输的负担会加重，系统响应速度也较慢，一旦业务规则发生变化，需要进行大量的代码修改工作，尤其是对于非常复杂的数据库操作，作量会成倍增长，与此相应的系统调试的工作量也很大。

这非常不利于系统的维护和使用，同时造成了系统客户端的工作量的加大，而服务器强大的处理能力又被闲置。

针对这种弊端，几乎所有的大型系统都使用存储过程来进行数据库操作。

采用这种数据库操作模式，可以把应用程序和数据库操作相对独立开来，分别管理。

关键字：信息技术, Oracle, 数据管理, 存储过程, 数据保密, 数据库, 数据库技术, 数据库系统引言在Oracle 中，复杂的业务规则和应用逻辑可作为过程（procedure）存储。

存储过程是一组SQL 和PL/SQL 语句，它允许我们把加强业务规则的代码从应用移动到数据库中。

结果是，代码只存储了一次，却可以被多个应用使用。

因为Oracle 支持存储过程，应用中的代码可以变得更紧凑一致和更易于维护。

使用存储过程可以极大地提高数据访问效率，提升整个应用系统的性能。

毕业设计文献综述计算机科学与技术基于web的网络存储服务系统的设计与实现一、前言部分写作目的：随着电子技术与网络的发展人们无须带着厚重的公文包到处走动，网络存储（网络硬盘）的出现使大家的文件保存处理运用更加方面简易。

为了更容易在朋友同事同学之间分享信息，为了更好的管理你的文件，网络存储是不二的选择。

有关概念、综述范围：（一）什么是网络存储[1]：存储（Storage）这个词汇，受限于传统的“存储”词义制约，容易被误解为被动的数据保存。

实质上，今天的IT用户和专家们都一致认同如下的概念：（1）存储系统是应用系统的基础框架（infrastructure）。

只是奠定了高度可管理、可扩展、兼容何种主机平台、安全、保证数据访问性能、满足多种数据使用要求的存储系统。

（2）存储系统在整个信息生命周期中，即数据的创建、保护、存取、迁移、存档、处置的整个过程中，扮演这管理调度的核心角色。

企业IT应用越深入，对存储系统的数据管理能力和功能的依赖性越强。

（3）网络存储的主要形式就是DAS、NAS和SAN[2]。

(1)DAS（Direct Attached Storage，直接连接存储）将磁盘阵列、磁带库等数据存储设备通过扩展接口直接连接到服务器或客户端。

DAS 以服务器为中心，不带有存储操作系统，即存储设备是服务器的一部分，I/O 请求将直接发送到存储设备。

DAS 方式实施比较简单，成本低，见效快。

但是存储管理工作比较繁琐，容量不能再分配，性能、扩充性较差。

因此该技术已经不能适应当今的存储要求。

NAS(Network Attached Storage ———网络连接存储)即将存储设备通过标准的网络拓扑结构(例如以太网) ,连接到一群计算机上,提供数据和文件服务。

(2)NAS 是一种专业的网络文件存储及文件备份设备,或称为网络直连存储设备、网络磁盘阵列。

一个NAS 里面包括核心处理器、文件服务管理工具、一个或者多个硬盘驱动器用于数据的存储。

存储器输入输出访问中英文资料对照外文翻译文献综述附录A：英文资料Input/Output AccessingIn this article, we will look at the three basic methods of I/O accessing －programmed I/O, interrupt-driven I/O, and direct memory access (DMA). The key issue that distinguishes these three methods is how deeply the processor is involved in I/O operations. The discussion emphasizes interrupt-driven I/O, because it is based on the concept of interrupt handling, which is a general problem that goes beyond Input/Output operations. The study of interrupt handling also aids in understanding the general concept of exception processing, which is an important issue not only for I/O, but also for interfacing a computer with other system control functions.Addressing I/O RegistersInput/Output devices communicate with a processor through Input/Output ports. Through the input ports, s processor receives data from the I/O devices. Through the output ports, a processor sends data to the I/O devices. Each I/O port consists of a small set of registers, such as data buffer registers (the input buffer and/or the output buffer), the status register, and the control register. The processor must have some means to address these registers while communicating with them. There are two common methods of addressing I/O register －memory-mapped I/O and direct I/O.1. Memory-Mapped I/OMemory-mapped I/O maps the I/O registers and main memory into a unified address space in the computer system. I/O registers share the same address space with main memory, but are mapped to a specific section that is reserved just for I/O. Thus, the I/O register can be addressed in ordinary memory reference instructions as if they are part of the main memory locations. There are no specially designed I/O instructions in the instruction set of the system. Any instruction that references a location in this area is an I/O instruction. Any instruction that can specify a memory address is capable of performing I/O operations. The Motorola MC68000 is an example of a computer system that uses this addressing method.2. Direct I/OThe method of addressing I/O registers directly without sharing the address space with the main memory is called direct I/O or I/O-mapped I/O. In other words, I/O registers are not mapped to the same address space with the main memory. Each I/O register has an independent address space. As a result, instructions that reference the main memory space cannot be used for Input/Output. In the instruction set of the computer system, special I/O instructions must be designed for I/O operations. In these I/O instructions, distinct I.D. numbers must be used to address different I/O communication channels (i.e., I/O ports). They are called port numbers. The I/O registers of an I/O port are connected to the system I/O bus, through which the processor can reference the I/O registers directly to send/receive data to/from an I/O device. An I/O port number is not from the same address space as main memory. The Pentium is an example of a computer system that uses the direct I/O addressing method. It has a 64 GB memory address space (32 address bits) and, at the same time, a 64 KB I/O address space (16 bits I/O address/port number).We can compare memory-mapped I/O and the direct I/O and the direct I/O as follows:●Memory-mapped I/O uses ordinary memory reference instructions to access I/O, so it provides flexibility for I/O programming and simplifies I/O software. Direct I/O does not provide any flexibility in I/O programming, since only a small set of special I/O instructions are allowed to reference I/O registers.●for memory-mapped I/O, the processor uses the same address lines to access all the addressable I/O registers and the same data lines to send/receive data to/form these registers. This simplifies the connection between I/O port and the processor, and thus leads to a low-cost hardware design and implementation. For direct I/O, the connection between I/O ports and the processor may be more expensive. This is because either (1) special hardware is needed to implement separate I/O address lines or (2) when memory address lines are used for I/O; a special flag is needed, indicating that the requested address is for an I/O operation.●In spite of the advantage of using ordinary memory reference instructions to access I/O registers, memory-mapped I/O may complicate the control unit design in regards to the implementation of I/O-related instructions. This is because usually the I/O bus cycles need to be longer than the equivalent memory bus cycles, and this means that the design of different timing control logic is required. This can be used to explain why memory-mapped I/O benefits programmers, but not electronics engineers.●Direct I/O addressing has another advantage over memory-mapped I/O in that low-level debugging on a differentiated addressing system may be easier, because break-points or error traps can be imposed more generally.●with memory-mapped I/O, I/O registers share the same address space with main memory; hence, the memory space available for programs and data is reduced. For direct I/O addressing, I/O does not share memory space with main memory, and a single contiguous memory space can be maintained and used by programmers.Programmed I/OProgrammed I/O requires that all data transfer operations be put under the complete control of the processor when executing programs. It is sometimes called polling, because the program repeatedly polls (checks) the status flag of an I/O device, so that its input/output operation can be synchronized with the processor. A general flowchart of such a program is shown in Figure 1. The program continuously polls the status of an I/O device to find out whether (1) data is available in the input buffer or (2) the output device is ready for receiving data from the processor. If the status shows “available” the program will execute a data transfer instruction to complete the I/O operation; otherwise, the busy status of the I/O device will force the program to circulate in a busy-waiting loop until the status becomes available. Such a busy-waiting loop, which continuously checks the status of data availability (for input) or device availability (for out-put), forms the typical program structure of programmed I/O. It is this time-consuming busy-waiting loop that wastes processor time and makes programmed I/O very inefficient. The processor must be involved continuously in the entire I/O process. During this time interval, the processor cannot perform any useful computation, but only serve a single I/O device. For certain slow I/O devices, this busy-waiting loop interval may be long enough that the processor could execute millions of instructions before the I/O event occurs, e.g., a key stroke on a keyboard.The operational mode lf programmed I/O stated above is characterized by the busy waiting loop of the program, during which the processor spends time polling an I/O device. Because of the dedication of the processor to a single task, this mode of programmed I/O is called dedicated polling or spin polling. Although dedicated polling is highly inefficient, sometimes it is necessary and even unavoidable. In a particular case, if an urgent event needs an immediate response without delay, then dedicated polling by a dedicated processor may be the best way to handle it. Once the expected event happens, the processor can tract to it immediately. For example, certain real time systems (e.g., radar echo processing systems) require a reaction to incoming data that is so quick that even an interrupt response is too slow. Under such a circumstance, only a fast dedicated polling loop may suffice.Another mode of operation of programmed I/O is called intermittent polling or timed polling. In this mode, the processor may poll the device at a regular timed interval, which can be expectedor prescheduled. Such a device can be found in many embedded systems where a special-purpose computer is used for process control, data acquisition, environmental monitoring, traffic counting, etc. these devices, which measure, collect, or record data, are usually polled periodically in a regular schedule determined by the needs of the application. Such a method of intermittent polling can help save time lost in spin polling and avoid the complexity of interrupt processing. However, it should be noted that intermittent polling may not be applicable in some special cases, in which there is only one device to be polled and the correct polling rate must be achieved with the assistance of an interrupt-driven clock. Using timed polling in this case would result in simply swapping one interrupt-driven clock. Using time polling in this case would result in simply swapping one interrupt requirement for another.Interrupt-Driven I/OInterrupt-driven I/O is a means to avoid the inefficient busy-waiting loops, which characterize programmed I/O. Instead of waiting while the I/O device is busy doing its job of input/output, the processor can run other programs. When the I/O device completes its job and its status becomes “available”, it will issue an interrupt request to the processor, asking for CPU service. In response, the processor suspends whatever it is currently doing, in order to attend to the needs of that I/O device.In respond to an interrupt request, the processor will first save the contents of both the program counter and the status register for the running program, and then transfer the control to the corresponding interrupt service routine to perform the required data input/output operation. When the interrupt service routine has completed its execution and if no more interrupt requests are pending, the processor will resume the execution of the previously interrupted program and restore the contents of the statuses and program counter. The processor hardware should check the interrupt request signal upon completion of execution of every instruction. If multiple devices issue their interrupt requests at the same time, the processor must use some method to choose which one to service first, and then service all the other interrupt requests one by one by order of priority. Only after all the interrupt requests have been serviced will the CPU return to the interrupted user program. In this way, the processor can serve many I/O devices concurrently and spend more time doing useful jobs, rather than running a busy-waiting loop to serve a single device. Therefore, interrupt I/O is very effective in handling slow and medium-speed I/O devices. Furthermore, the concept of an interrupt can be generalized to handle any event caused by hardware or software, internally or externally. This general problem is referred to as exception processing.If multiple interrupt requests are issued by different devices at the same time, the processor should have some means to identify the interrupt sources and handle their interrupt requests by some policy, typically by priority. Only one request with the highest priority can be serviced at the current time, while all others are put into a waiting queue. Upon the completion of the service performed by an interrupt service routine, the processor should search the waiting queue for all the pending interrupt requests, old or new, and continue to service them one by one according to their priorities, until the queue becomes empty. Only when all the pending interrupt requests have been serviced can the interrupted user program be resumed. Although this case contains multiple interrupt requests, it is still a simplified case. The assumption is that all the interrupt service routines must be completed without further interruption 9 (or so-called preemption) once they have been started one after another by the processor. An interrupt process satisfying this assumption is called a non-preemptive interrupt. In real-life circumstances, the process of interrupt-driven I/O can be more complicated than this simplified case. Each interrupted service routine running in the processor can be preempted (interrupted) by a newly arrived interrupt request, which has a higher priority than the current one. This circumstance will cause the main program and all the requested interrupt service routines to have a complicated interrelationship. An interrupt process that allows an interrupt service routine to be preempted by a higher-priority interrupt service routine is called a preemptive interrupt.Direct Memory AccessAlthough interrupt I/O is more efficient than the programmed I/O, it still suffers from a relatively high overhead with respect to handling the interrupt. This overhead includes resolving the conflict among multiple interrupt requests, saving and restoring the program contexts, pooling for interrupt identification, branching to/from the interrupt service routine, etc. Using an interrupt is a wasteful activity that can take several microseconds to complete.Direct memory access(DMA) is a method that can input/output a block of data directly to/form main memory with a speed of one data item per memory cycle, without continuous involvement of the processor. The entire process is implemented by the hardware of a DMA controller, which takes the place of the processor and communicates directly with main memory. As a result, the block diagram of the computer system changes form processor-centered to memory-centered. Hence, from the viewpoint of I/O processing, the processor is no longer the center of a computer, but rather a partner with which the I/O subsystem competes for memory bus cycles to input/output data item to/from main memory. However, a DMA controller is designed to exchange data in blocks, so it works well with the large-volume high-speed block-oriented I/Odevices, such as high-speed disks and communication networks.The DMA controller can work in two different modes. Normally, it works concurrently with the processor, competing for individual memory bus cycles to input/output successive words of a data block. If the I/O speed is not very high, the memory accesses by the processor and the DMA controller can be interwoven. Time is accrued on a cycle-by-cycle basis. Neither the processor nor the DMA controller can continuously use all the memory bus cycles during any time interval. This operational mode of the DMA controller is called cycle stealing, so named because the I/O subsystem is essentially “stealing” memory bus cycles from the processor. This mode integrates the DMA memory accesses into CPU activity and avoids serious disruption of the main processing. Alternatively, for even higher I/O transfer speed, DMA operations require bus time, which can be allocated in block of cycles known as bursts. During a burst of memory cycles, the processor is totally excluded from accessing memory. The DMA controller is given exclusive access to main memory and continuously inputs/outputs blocks of data at a speed comparable to the memory speed. This operational mode of the DMA controller is called the block or burst mode. A DMA controller designed for this mode of operation usually incorporates a data storage buffer with a capacity matching the size of at least one data block. When the DMA controller utilizes the memory bus, it can transfer a data block directly between its data storage buffer and main memory.The following registers are necessary for the DMA to transfer a block of data:● Data buffer register (DBR)－it can be implemented as two registers, one for inputand the other for output, or even a set of registers comprising a data storage buffer.● DMA address register (DAR)－used to store the starting address of the memorybuffer area where the block of data is to be read or written.● Word counter (WC)－the contents specify the number of words in the block of dataremaining to be transferred and it is automatically decremented after each word is transferred.● Control/status register (CSR)－used by the processor to send control information tothe DMA controller and to collect the statuses and error information of the DMA controller and the I/O devices attached to it.Using these registers, the DMA controller knows the addresses of the source and destination data blocks, as well as the quantity of data to be transferred. Once the DMA controller acquires the memory bus, the block transfer operation can be performed autonomously using the information contained in these registers, without the continuous involvement of the processor.Besides the above-listed registers, the DMA controller should contain the control logic of a bus request facility, which performs bus arbitration using the signals of DMA request (DMAR)and DMA acknowledge (DMAA). Bus arbitration is the process of resolving the contention among multiple concurrently operating DMA controllers for acquisition of the memory bus. The selection of the bus master is usually based on the priorities of various DMD devices. Among different DMA devices, the priority order are arranged by the degree urgency of the devices receiving the DMA service, i.e., according to their speed requirements. There are two approaches to bus arbitration for DMA devices －centralized and distributed －which are similar to the approaches used to identify interrupt sources using signals for interrupt request (INTR) and interrupt acknowledge (INTA).Although the transfer of the data block is performed by the DMA without involvement of the processor, the overall operation of the DMA controller is still determined by the CPU via interrupts. It serves two purposes as follows: (1) Before the DMA controller starts the data transfer, all the registers must be initialized by the processor. (2) When the DMA finishes a block transfer operation, it should inform the processor of completion by issuing an interrupt, which allows the processor to post-process the data in the memory buffer area or handle possible error conditions. Therefore, the DMA controller often issued interrupt request (INTR) and receives interrupt acknowledge (INTA) signals.DNA relieves the processor form the burden of I/O function, except for the initialization of the transfer of parameters and the post-processing of data. It is very efficient when serving high-speed I/O devices. However, the role of DMA is not limited to the area of input/output. In contemporary computer systems, DMA has been developed into a general technique of time-sharing the main memory bandwidth between I/O subsystem processing and CPU processing. In the I/O subsystem, high-speed I/O devices, such as disks, CD-ROMs, DVDs, graphics, video equipment, and high-speed networks, want to share main memory bandwidth through the DMA. In the area of central processing and the main memory system, (1) running programs, (2) the operating system, and (3) dynamic RAM refreshing are all sharing the main memory bandwidth, DMA is the appropriate way to implement this time-sharing. Faster 16-bit Ultra DMA has now replaced the outdated 8-bit facilities. Commercially available DMA controller chips now offer multiple channels, allowing concurrent data transfer. For example, one channel can be reserved for DRAM refreshing; another channel can perform memory-to memory block moves, etc. To further free the processor from handling slow tasks, powerful channel processors have been developed with autonomous capabilities, including device polling, channel program execution, interrupt activation and DMA for data and instructions. They have become a growing class of semi-independent co-processors communicating with the main processor. They can be assigned dedicated tasks, such as floating-point calculations, graphic processing, network communication,large database management, etc. The growing bus contention problem, due to time-sharing main memory bandwidth, can be alleviated by more effectively using cache memory. For example, in the Pentium processor, L1 cache allows the CPU pipeline to continue fetching and executing, as long as the demand can be satisfied with instructions held locally in the cache.附录B：英文资料翻译输入/输出访问在这一篇文章中，我们将会研究三种基本的输入／输出访问方法：程控I/O、中断驱动I/O以及直接存储器访问（DMA）。

---------------------------------------------------------------范文最新推荐------------------------------------------------------ WinDriver基于PCIE的数据存储卡开发+文献综述摘要随着高速采集系统、图像采集系统等测试系统的发展，在测试中产生的大容量数据如何快速传入计算机进行分析处理成为制约系统性能进一步提高及系统功能实现的一个重要环节。

在此背景下，通过研制以DDS产生数据并通过PCI Express计算机总线将数据传入计算机的传输卡，实现将外部数据高速传入计算机。

论文在分析任务及技术指标的基础上，设计了系统总体方案。

在硬件实现部分，介绍了基于PCI Express 总线高速传输过程中的相关技术，对FPGA实现PCI Express总线接口、FPGA实现DMA传输、FPGA进行中断管理等技术进行了详细的讨论；在软件部分，结合系统读取数据过程讨论了利用WinDriver开发设备驱动，并且对驱动程序与应用程序的开发步骤进行了详细的论述。

系统的调试与测试验证了基于PCI1 / 18Express X1接口的传输卡数据传输的可行性和正确性。

8405关键词PCI ExpressFPGAIP核WinDriver毕业设计说明书（论文）外文摘要TitleDevelopment of data storage card based on PCI ExpressAbstractAlong with the development of test systems such as high-speed integrated system，image collection and so on，how to transfer a large amount of data produced in testing process to analyze and process them becomes the key problem that restricts system performance improvement and system function achievement. With this background, high-speed transmission of exterior data into computer is realized by using DDS to generate data and transferring the data into computer through PCI Express computer bus.---------------------------------------------------------------范文最新推荐------------------------------------------------------The general plan of system is designed in this paper on the basis of analyzing task and technical indexes. Correlative techniques in the process of high speed data transmission based on PCI Express bus is introduced in the hardware part. Many technologies such as FPGA achieving PCI Express bus, FPGA achieving DMA transmission, FPGA performing intermitting management and so on are discussed in detail. In software part, using WinDriver to develop device driver are introduced combining the process of reading the data by system, and the steps of develop drivers and applications are discussed in detail. The debugging and testing of the system verify the feasibility and correctness of data transmission based on PCI Express X1 interface.3.6本章小结194驱动程序设计193 / 184.1引言194.2利用WinDriver开发设备驱动19 4.2.1开发工具的选择194.2.2WinDriver工作原理204.3驱动程序与应用程序的开发20 4.3.1生成INF文件和用户函数21 4.3.2安装设备驱动234.3.3应用程序的开发244.4本章小结275系统调试及结果分析275.1调试环境27---------------------------------------------------------------范文最新推荐------------------------------------------------------ 5.1.1硬件系统275.1.2设计软件285.1.3本章内容285.2系统调试过程295.3调试结果与分析315.3.1数据传输速率315.3.2数据传输的完整性325.4本章小结34结论35致谢36参考文献375 / 181绪论1.1课题研究背景I/O总线的发展历程粗略地可划分为三代：第一代总线包括ISA、EISA、MC和VESA。

2024年文献综述在2024年，随着全球数字化趋势的不断推进，文献综述也进一步发展和完善。

文献综述是一种通过收集、搜集、筛选、分析和综合以往研究成果来评价、总结和探讨特定领域研究进展和前沿的方法。

它已经成为科学研究的重要组成部分，对于学术论文、科研项目和决策提供了重要参考。

随着、大数据以及计算机技术的不断发展，文献综述也出现了许多新的变化和特点，其研究内容和方法逐步走向数字化、智能化和综合化的方向。

一、数字化数字化是社会科技发展的重要标志，它对于文献综述的实现具有重要意义。

数字化意味着文献采集、整理、存储、传播和利用从传统的纸质形式转向数字形式，大大提高了处理速度、范围和可靠性。

数字化文献库、文献数据库、文献搜索引擎、文献管理软件等数字化工具，大大方便了文献的检索和利用。

二、智能化智能化是技术不断发展的结果，它增强了文献综述的自动化、智能化和人性化。

智能化文献检索、文献分类、文献排名、文献分析等工具，可以更加精准地定位目标领域和研究问题，提高信息质量和效率。

同时，智能化技术还可以扩大文献综述的范围和深度，挖掘出更多的有用信息和见解。

三、综合化综合化是指文献综述不再是单一学科或单一领域的内容，而是涉及多个学科、多个领域和多个层面的综合性内容。

综合化的文献综述不仅可以扩大研究视野和深度，而且可以更好地反映出人类知识体系和社会发展趋势。

同时，综合化文献综述还可以促进学科交叉和跨界合作，有利于推进科学技术的全面进步和社会进步。

在数字化、智能化和综合化的大趋势下，文献综述正朝着更加精准、高效、全面和人性化的方向快速发展。

未来，我们可以期待在文献综述领域取得更多的突破和创新，为学术发展和社会进步作出更大的贡献。

存储器芯片的使用现状及未来发展趋势文献综述班级:XXX姓名:XXX学号：XXX一、选题背景存储器广泛应用于计算机、消费电子、网络存储、物联网、国家安全等重要领域，是一种重要的、基础性的产品。

当前，伴随着第五代移动通信、物联网和大数据的快速发展，存储器的需求量迅速增加，存储容量、存取速度、功耗、可靠性和使用寿命等指标要求也越来越高。

世界各大企业在这方面出现“百家争鸣、百花齐放"的大好局面，涌现出多种新型存储器，并且工艺水平和性能都在不断提高，给消费者提供了更多的选择空间。

二、相关问题现状研究综述我们一般会将存储器划分为,易失性存储器和非易失性存储器，这种划分是根据断电后数据是否丢失而决定的。

现有技术中,整个存储器芯片行业主要有三种种产品：DRAM、NAND FLASH和NOR FLASH。

DRAM是易失性存储器的代表，NAND Flash和NOR FLASH是非易失性存储器的代表.尽管按照不同的分类特点,可形成存众多种类的储存芯片,但从该行业产业结构分析，上述三种存储器毫无疑问是全球重点厂商最为关注的产品领域。

NAND FLASH和DRAM都是硅基互补金属氧化物半导体器件,在摩尔定律和海量数据存储需求的推动下，不断向大容量、高密度、快速、低功耗、长寿命方向发展.但随着特征尺寸不断减小至接近原子级，传统平面型结构遇到无法跨越的性能障碍，存储器的性能和可靠性达到极限，而且新工艺节点开发成本迅速增加，进一步降低预期收益。

因此，存储器向两大方向转型发展：一是继续沿用硅基材料，用垂直堆叠替代特征尺寸微缩，从平面转向立体结构；二是使用新材料和新结构研制新兴传感器技术。

前者的挑战是开发出可实现8层到32层甚至64层连续堆叠的材料和生产工艺，并保证每一层存储器性电性能的一致可控.后者的挑战是论证开发配套生产工艺,并保证新材料不会对既有生产线造成污染、产品性能优于现有存储器和可长期可靠使用等。

新材料、结构和物理效应方面研究的不断突破，使得其他新兴存储器技术也因此得到发展。

文献综述存储管理(memory management)，即是对存储器的管理。

在计算机系统中,存储器的功能是保存各种信息。

它又分为CPU能直接访问的内存和不能直接访问的外存。

两者物理特性不同，操作系统对它们的管理方式也不同。

内存由顺序编址的块组成；每块包含相应的物理单元。

CPU要通过启动相应的输入／输出设备后才能使外存与内存交换信息。

内存管理方法有：分区式管理、页式管理、段式管理和段页式管理。

内存管理的核心问题是如何解决内存和外存的统一，以及它们之间的数据交换问题。

内存和外存的统一管理使得内存的利用率得到提高，用户程序不再受内存可用区大小的限制。

与此相关联，内存管理要解决内存扩充、内存的分配与回收、虚拟地址到内存物理地址的变换、内存保护与共享、内外存之间数据交换的控制等问题。

内存由大规模集成电路实现，它的发展方向是高速、大容量和小体积。

内存又分为ROM和RAM， ROM为固化只读的。

因此操作系统的存储管理模块管理的是内存中的RAM。

内存可以看作是以字或字节为单位的存储单元组成的数组,每个存储单元都有自己的地址。

内存的作用：存储指令和数据。

程序执行时，先加载到内存。

CPU执行时，从内存取指令，分析指令，如需要从内存取操作数。

执行完毕后，存储运算结果到内存内存扩充：内存的逻辑扩充：即在不改变实际内存容量情况下，借助大容量外存解决内存不足问题内存分配和回收：为运行的进程分配内存空间,并在不需要时回收它们占据的空间。

借助描述内存使用情况的数据结构和相应算法实现。

分区管理分配算法：最先适应（first-fit）：第一个满足条件的空闲区；最佳适应（best-fit）：满足条件中最小的空闲区，即最“合体”的；最坏适应（worst-fit）：满足条件中最大的空闲区。

碎片(fragment)的概念：内部碎片（internal fragment ）和外部碎片（external fragment ）。

虚拟存储器：在程序装入时，不必将其全部读入到内存，而只需将当前需要执行的部分页或段读入到内存，就可让程序开始执行。

分布式存储系统是一种将数据存储于多个物理位置的系统。

这种系统强调多个存储设备之间的通信和协调，使得用户可以像访问本地存储设备一样访问分布式存储系统。

分布式存储系统具有高可靠性、高性能、高可扩展性等特点，在当今大数据时代，受到了越来越多的关注和应用。

在研究和应用过程中，参考文献是非常重要的，下面是一些关于分布式存储系统的参考文献，供大家参考。

一、关于分布式存储系统概述的参考文献1. Ghemawat, S., Gobioff, H., Leung, S. (2003). The Google file system. ACM SIGOPS Operating Systems Review, 37(5), 29-43.这篇文章介绍了谷歌文件系统，详细分析了分布式存储系统的设计和实现细节。

2. Anderson, D. P. (1980). More is less: a bag of long words for the Compression Project. ACM Transactions on Computer Systems (TOCS), 8(4), 353-374. 本文介绍了一种用于分布式存储系统的数据压缩算法，对系统性能有很好的提升。

二、关于分布式存储系统关键技术的参考文献1. Ousterhout, J. K., et al. (1988). The Sprite network operating system. IEEE Computer, 21(2), 23-36. 该文介绍了一个应用于分布式存储系统中的网络操作系统，对系统的可靠性和性能有很大的提升。

2. DeCandia, G., et al. (2007). Dynamo: Amazon's highly av本人lable key-value store. ACM SIGOPS Operating Systems Review, 41(6), 205-220. 本文介绍了亚马逊的高可用性键值存储系统，对于分布式存储系统的一致性和可靠性有很好的参考价值。

文献综述手持示波器的现状手持数字示波表是近年出现的一种新型的检测仪表,主要功能覆盖数字存储示波器和数字万用表,可满足机动现场维护、后勤保障、工业生产以及教育系统等领域移动测试的需求。

与台式的数字示波器相比,手持数字示波表具有轻巧、便携的特性,可以满足现场苛刻环境下的精确测量。

目前国内市场上常见的国外品牌有Fluke、Tektronix、Metrix 、Svmmit、Velleman、Metex等,其中美国福禄克(Fluke作为手持示波表测量领域的行业龙头,形成了强大的品牌效力。

从国内的的市场调查来看,国内近几年对手持示波表的需求量每年可达上万台。

F120系列是福禄克(Fluke公司销售量较大的产品系列,分F123和F124两款,带宽分别为20MHz 和40MHz,采样率为25MSa/s。

因此,从行业需求上来看,20MHz带宽的产品是目前市场的主流。

面对这样的行业需求,国内示波器生产企业把产品性能设定在20MHz带宽、100MSa/s采样率。

采用双通道数据采集,一般是单色LCD显示。

一、几款手持示波器的参数● AEMC OX 7104-C(100MHz,四通道;● Fluke 199C(200MHz,两通道;● Agilent Technologies U1604A(40MHz,两通道;● Protek 860F(60MHz,两通道。

AEMC OX 7104-CAEMC的OX 7104-C是市售的唯一一种四通道手持式示波器。

12位分辨率、100MHz 带宽和触摸显示屏使其性能居于领先地位。

5995美元的高价格使其较适合于确实很需要便携性的场合。

如果不是特别需要便携性,可以找到大量具有相当价格和性能的台式示波器,不过多数都只有8位分辨率,而AEMC的分辨率为12位。

AEMC的手持式示波器包括一个谐波分析仪,适用于分析电源质量,可覆盖40Hz到450Hz的频率范围。

在低电压下,在最高5kHz的频率下可获得可靠的结果。