虫虫首页| 资源下载| 资源专辑| 精品软件
登录| 注册

Read-only

  • 存储器技术.doc

    存储器技术.doc 计算机的主存储器(Main Memory),又称为内部存储器,简称为内存。内存实质上是一组或多组具备数据输入输出和数据存储功能的集成电路。内存的主要作用是用来存放计算机系统执行时所需要的数据,存放各种输入、输出数据和中间计算结果,以及与外部存储器交换信息时作为缓冲用。由于CPU只能直接处理内存中的数据 ,所以内存是计算机系统中不可缺少的部件。内存的品质直接关系到计算机系统的速度、稳定性和兼容性。 4.1 存储器类型计算机内部存储器有两种类型,一种称为只读存储器ROM(Read Only Memiry),另一种称为随机存储器RAM(Random Access Memiry)。 4.1.1 只读存储器只读存储器ROM主要用于存放计算机固化的控制程序,如主板的BIOS程序、显卡BIOS控制程序、硬盘控制程序等。ROM的典型特点是:一旦将数据写入ROM中后,即使在断电的情况下也能够永久的保存数据。从使用上讲,一般用户能从ROM中读取数据,而不能改写其中的数据。但现在为了做一日和尚撞一天钟于软件或硬件程序升级,普通用户使用所谓的闪存(Flash Memiry)也可以有条件地改变ROM中的数据。有关只读存储器ROM的内容将在第11章中介绍,本章主要介绍随机存储器。4.1.2 随机存取存储器随机存取存储器RAM的最大特点是计算机可以随时改变RAM中的数据,并且一旦断电,TAM中数据就会立即丢失,也就是说,RAM中的数据在断电后是不能保留的。从用于制造随机存取存储器的材料上看,RAM又可分为静态随机存储器SRAM(Static RAM)和动态随机存储器DRAM(Dymamic RAM)两种。1. 动态随机存储器在DRAM中数据是以电荷的形式存储在电容上的,充电后电容上的电压被认为是逻辑上的“1”,而放电后的电容上的电压被认为是逻辑上的“0”认。为了减少存储器的引脚数,就反存储器芯片的每个基本单元按行、列矩阵形式连接起来,使每个存储单元位于行、列的交叉点。这样每个存储单元的地址做一日和尚撞一天钟可以用位数较少的行地址和列地址两个部分表示,在对每个单元进行读写操作时,就可以采用分行、列寻址方式写入或读出相应的数据,如图4-1所示。  由于电容充电后,电容会缓慢放电,电容 上的电荷会逐渐

    标签: 存储器

    上传时间: 2014-01-10

    上传用户:18752787361

  • Although there has been a lot of AVL tree libraries available now, nearly all of them are meant to w

    Although there has been a lot of AVL tree libraries available now, nearly all of them are meant to work in the random access memory(RAM). Some of them do provide some mechanism for dumping the whole tree into a file and loading it back to the memory in order to make data in that tree persistent. It serves well when there s just small amount of data. When the tree is somewhat bigger, the dumping/loading process could take a lengthy time and makes your mission-critical program less efficient. How about an AVL tree that can directly use the disk for data storage ? If there s something like that, we won t need to read through the whole tree in order to pick up just a little bit imformation(a node), but read only the sectors that are neccssary for locating a certain node and the sectors in which that node lies. This is my initial motivation for writing a storage-media independent AVL Tree. However, as you step forth, you would find that it not only works fine with disks but also fine with memorys, too.

    标签: available libraries Although nearly

    上传时间: 2014-01-22

    上传用户:zhoujunzhen

  • 常用串行EEPROM的编程应用

    常用串行EEPROM的编程应用,EEPROM是"Electrically Erasable Programmable Read-only"(电可擦写可编程只读存储器)的缩写,EEPROM在正常情况下和EPROM一样,可以在掉电的情况下保存数据,所不同的是它可以在特定引脚上施加特定电压或使用特定的总线擦写命令就可以在在线的情况下方便完成数据的擦除和写入

    标签: EEPROM 串行 编程应用

    上传时间: 2014-01-19

    上传用户:xmsmh

  • I want to provide an example file system driver for Windows NT/2000/XP. For some time I have worked

    I want to provide an example file system driver for Windows NT/2000/XP. For some time I have worked on an implementation of RomFs. RomFs is a small filesystem originally implemented in Linux, because of its simple disk layout its a good choice for an example driver. The current status is a working Read-only driver that supports caching of file data, the create functionallity still needs some work but I m releasing it due to the high public demand.

    标签: provide Windows example driver

    上传时间: 2013-12-19

    上传用户:zsjzc

  • it is about only read file about imdct

    it is about only read file about imdct

    标签: about imdct file only

    上传时间: 2013-11-27

    上传用户:二驱蚊器

  • The ZZIPlib provides read access on ZIP-archives. The library uses only the patent-free compression-

    The ZZIPlib provides read access on ZIP-archives. The library uses only the patent-free compression-algorithms supported by Zlib. It provides functions that transparently access files being either real files or zipped files, both with the same filepath

    标签: ZIP-archives compression patent-free The

    上传时间: 2017-01-02

    上传用户:yuzsu

  • 51串行令牌格式 a51编译 Read data from serial port and write into buffer DPTR pointed in XRAM if a data

    51串行令牌格式 a51编译 Read data from serial port and write into buffer DPTR pointed in XRAM if a data frame is received and calculate the check sum if a information frame is received return control byte only

    标签: data pointed buffer serial

    上传时间: 2015-06-14

    上传用户:极客

  • NAME Control_AT24Cxx This collection of routines allows an AT89C2051 microcontroller to read a

    NAME Control_AT24Cxx This collection of routines allows an AT89C2051 microcontroller to read and write the AT24Cxx family of serial CMOS EEPROMS. This version of the code is compatible only with the AT89C2051 due to the location of the data buffer and stack in RAM. The code may be modified to work with the AT89C1051 by relocating or resizing the buffer and stack to fit into the smaller amount of RAM available in the AT89C1051. Note that the minimum size of the buffer is determined by the page size of the AT24Cxx.

    标签: microcontroller Control_AT collection routines

    上传时间: 2013-12-13

    上传用户:asddsd

  • I2C Slave module The module contains N accessable Registers when in read Process, all Registers a

    I2C Slave module The module contains N accessable Registers when in read Process, all Registers are read at a time when in write Process, only the addressed register are Writeable.

    标签: Registers module accessable contains

    上传时间: 2016-05-13

    上传用户:xauthu

  • 基于HITAG读写芯片HTRC110的读写设备设计

    Designing read/write device (RWD) units for industrial RF-Identification applications is strongly facilitated by the NXP Semiconductors HITAG Reader Chip HTRC110. All needed function blocks, like the antenna driver, modulator demodulator and antenna diagnosis unit, are integrated in the HTRC110. Therefore only a minimum number of additional passive components are required for a complete RWD. This Application Note describes how to design an industrial RF-Identification system with the HTRC110. The major focus is dimensioning of the antenna, all other external components including clock and power supply, as well as the demodulation principle and its implementatio

    标签: HITAG HTRC 110 读写芯片

    上传时间: 2013-10-22

    上传用户:zhengjian