很多不同的厂家生产各种型号的计算机,它们运行完全不同的操作系统,但TCP.IP协议族允许它们互相进行通信。这一点很让人感到吃惊,因为它的作用已远远超出了起初的设想。T C P / I P起源于6 0年代末美国政府资助的一个分组交换网络研究项目,到9 0年代已发展成为计算机之间最常应用的组网形式。它是一个真正的开放系统,因为协议族的定义及其多种实现可以不用花钱或花很少的钱就可以公开地得到。它成为被称作“全球互联网”或“因特网(Internet)”的基础,该广域网(WA N)已包含超过1 0 0万台遍布世界各地的计算机。本章主要对T C P / I P协议族进行概述,其目的是为本书其余章节提供充分的背景知识。 TCP.IP协议 缩略语 ACK (ACKnowledgment) TCP首部中的确认标志 API (Application Programming Interface) 应用编程接口 ARP (Address Resolution Protocol) 地址解析协议 ARPANET(Defense Advanced Research Project Agency NETwork) (美国)国防部远景研究规划局 AS (Autonomous System) 自治系统 ASCII (American Standard Code for Information Interchange) 美国信息交换标准码 ASN.1 (Abstract Syntax Notation One) 抽象语法记法1 BER (Basic Encoding Rule) 基本编码规则 BGP (Border Gateway Protocol) 边界网关协议 BIND (Berkeley Internet Name Domain) 伯克利I n t e r n e t域名 BOOTP (BOOTstrap Protocol) 引导程序协议 BPF (BSD Packet Filter) BSD 分组过滤器 CIDR (Classless InterDomain Routing) 无类型域间选路 CIX (Commercial Internet Exchange) 商业互联网交换 CLNP (ConnectionLess Network Protocol) 无连接网络协议 CRC (Cyclic Redundancy Check) 循环冗余检验 CSLIP (Compressed SLIP) 压缩的S L I P CSMA (Carrier Sense Multiple Access) 载波侦听多路存取 DCE (Data Circuit-terminating Equipment) 数据电路端接设备 DDN (Defense Data Network) 国防数据网 DF (Don’t Fragment) IP首部中的不分片标志 DHCP (Dynamic Host Configuration Protocol) 动态主机配置协议 DLPI (Data Link Provider Interface) 数据链路提供者接口 DNS (Domain Name System) 域名系统 DSAP (Destination Service Access Point) 目的服务访问点 DSLAM (DSL Access Multiplexer) 数字用户线接入复用器 DSSS (Direct Sequence Spread Spectrum) 直接序列扩频 DTS (Distributed Time Service) 分布式时间服务 DVMRP (Distance Vector Multicast Routing Protocol) 距离向量多播选路协议 EBONE (European IP BackbONE) 欧洲I P主干网 EOL (End of Option List) 选项清单结束 EGP (External Gateway Protocol) 外部网关协议 EIA (Electronic Industries Association) 美国电子工业协会 FCS (Frame Check Sequence) 帧检验序列 FDDI (Fiber Distributed Data Interface) 光纤分布式数据接口 FIFO (First In, First Out) 先进先出 FIN (FINish) TCP首部中的结束标志 FQDN (Full Qualified Domain Name) 完全合格的域名 FTP (File Transfer Protocol) 文件传送协议 HDLC (High-level Data Link Control) 高级数据链路控制 HELLO 选路协议 IAB (Internet Architecture Board) Internet体系结构委员会 IANA (Internet Assigned Numbers Authority) Internet号分配机构 ICMP (Internet Control Message Protocol) Internet控制报文协议 IDRP (InterDomain Routing Protocol) 域间选路协议 IEEE (Institute of Electrical and Electronics Engineering) (美国)电气与电子工程师协会 IEN (Internet Experiment Notes) 互联网试验注释 IESG (Internet Engineering Steering Group) Internet工程指导小组 IETF (Internet Engineering Task Force) Internet工程专门小组 IGMP (Internet Group Management Protocol) Internet组管理协议 IGP (Interior Gateway Protocol) 内部网关协议 IMAP (Internet Message Access Protocol) Internet报文存取协议 IP (Internet Protocol) 网际协议 I RTF (Internet Research Task Force) Internet研究专门小组 IS-IS (Intermediate System to Intermediate System Protocol) 中间系统到中间系统协议 ISN (Initial Sequence Number) 初始序号 ISO (International Organization for Standardization) 国际标准化组织 ISOC (Internet SOCiety) Internet协会 LAN (Local Area Network) 局域网 LBX (Low Bandwidth X) 低带宽X LCP (Link Control Protocol) 链路控制协议 LFN (Long Fat Net) 长肥网络 LIFO (Last In, First Out) 后进先出 LLC (Logical Link Control) 逻辑链路控制 LSRR (Loose Source and Record Route) 宽松的源站及记录路由 MBONE (Multicast Backbone On the InterNEt) Internet上的多播主干网 MIB (Management Information Base) 管理信息库 MILNET (MILitary NETwork) 军用网 MIME (Multipurpose Internet Mail Extensions) 通用I n t e r n e t邮件扩充 MSL (Maximum Segment Lifetime) 报文段最大生存时间 MSS (Maximum Segment Size) 最大报文段长度 M TA (Message Transfer Agent) 报文传送代理 MTU (Maximum Transmission Unit) 最大传输单元 NCP (Network Control Protocol) 网络控制协议 NFS (Network File System) 网络文件系统 NIC (Network Information Center) 网络信息中心 NIT (Network Interface Tap) 网络接口栓(S u n公司的一个程序) NNTP (Network News Transfer Protocol) 网络新闻传送协议 NOAO (National Optical Astronomy Observatories) 国家光学天文台 NOP (No Operation) 无操作 NSFNET (National Science Foundation NETwork) 国家科学基金网络 NSI (NASA Science Internet) (美国)国家宇航局I n t e r n e t NTP (Network Time Protocol) 网络时间协议 NVT (Network Virtual Terminal) 网络虚拟终端 OSF (Open Software Foudation) 开放软件基金 OSI (Open Systems Interconnection) 开放系统互连 OSPF (Open Shortest Path First) 开放最短通路优先 PAWS (Protection Against Wrapped Sequence number) 防止回绕的序号 PDU (Protocol Data Unit) 协议数据单元 POSIX (Portable Operating System Interface) 可移植操作系统接口 PPP (Point-to-Point Protocol) 点对点协议 PSH (PuSH) TCP首部中的急迫标志 RARP (Reverse Address Resolution Protocol) 逆地址解析协议 RFC (Request For Comments) Internet的文档,其中的少部分成为标准文档 RIP (Routing Information Protocol) 路由信息协议 RPC (Remote Procedure Call) 远程过程调用 RR (Resource Record) 资源记录 RST (ReSeT) TCP首部中的复位标志 RTO (Retransmission Time Out) 重传超时 RTT (Round-Trip Time) 往返时间 SACK (Selective ACKnowledgment) 有选择的确认 SLIP (Serial Line Internet Protocol) 串行线路I n t e r n e t协议 SMI (Structure of Management Information) 管理信息结构 SMTP (Simple Mail Transfer Protocol) 简单邮件传送协议 SNMP (Simple Network Management Protocol) 简单网络管理协议 SSAP (Source Service Access Point) 源服务访问点 SSRR (Strict Source and Record Route) 严格的源站及记录路由 SWS (Silly Window Syndrome) 糊涂窗口综合症 SYN (SYNchronous) TCP首部中的同步序号标志 TCP (Transmission Control Protocol) 传输控制协议 TFTP (Trivial File Transfer Protocol) 简单文件传送协议 TLI (Transport Layer Interface) 运输层接口 TTL (Ti m e - To-Live) 生存时间或寿命 TUBA (TCP and UDP with Bigger Addresses) 具有更长地址的T C P和U D P Telnet 远程终端协议 UA (User Agent) 用户代理 UDP (User Datagram Protocol) 用户数据报协议 URG (URGent) TCP首部中的紧急指针标志 UTC (Coordinated Universal Time) 协调的统一时间 UUCP (Unix-to-Unix CoPy) Unix到U n i x的复制 WAN (Wide Area Network) 广域网 WWW (World Wide Web) 万维网 XDR (eXternal Data Representation) 外部数据表示 XID (transaction ID) 事务标识符 XTI (X/Open Transport Layer Interface) X/ O p e n运输层接口
上传时间: 2013-11-13
上传用户:tdyoung
Byte2~Byte5 字节: 表示了仪表的测量值;高四位未使用,只使用了各字节的低四位。用BCD 码表示的数值,从高位到低 BYTE4 BYTE17 1 - 0 BATT MAX FULL A/C F/S START1 START2 UNIT_UP UNIT_DOWN 2 - 位依次为Byte5,Byte4,Byte3,Byte2。
上传时间: 2013-10-18
上传用户:thuyenvinh
在研究传统家用燃气报警器的基础上,以ZigBee协议为平台,构建mesh网状网络实现网络化的智能语音报警系统。由于传感器本身的温度和实际环境温度的影响,传感器标定后采用软件补偿方法。为了减少系统费用,前端节点采用半功能节点设备,路由器和协调器采用全功能节点设备,构建mesh网络所形成的家庭内部报警系统,通过通用的电话接口连接到外部的公用电话网络,启动语音模块进行报警。实验结果表明,在2.4 GHz频率下传输,有墙等障碍物的情况下,节点的传输距离大约为35 m,能够满足家庭需要,且系统工作稳定,但在功耗方面仍需进一步改善。 Abstract: On the basis of studying traditional household gas alarm system, this paper proposed the platform for the ZigBee protocol,and constructed mesh network to achieve network-based intelligent voice alarm system. Because of the sensor temperature and the actual environment temperature, this system design used software compensation after calibrating sensor. In order to reduce system cost, semi-functional node devices were used as front-end node, however, full-function devices were used as routers and coordinator,constructed alarm system within the family by building mesh network,connected to the external public telephone network through the common telephone interface, started the voice alarm module. The results indicate that nodes transmit about 35m in the distance in case of walls and other obstacles by 2.4GHz frequency transmission, this is able to meet family needs and work steadily, but still needs further improvement in power consumption.
上传时间: 2013-10-30
上传用户:swaylong
数字与模拟电路设计技巧IC与LSI的功能大幅提升使得高压电路与电力电路除外,几乎所有的电路都是由半导体组件所构成,虽然半导体组件高速、高频化时会有EMI的困扰,不过为了充分发挥半导体组件应有的性能,电路板设计与封装技术仍具有决定性的影响。 模拟与数字技术的融合由于IC与LSI半导体本身的高速化,同时为了使机器达到正常动作的目的,因此技术上的跨越竞争越来越激烈。虽然构成系统的电路未必有clock设计,但是毫无疑问的是系统的可靠度是建立在电子组件的选用、封装技术、电路设计与成本,以及如何防止噪讯的产生与噪讯外漏等综合考虑。机器小型化、高速化、多功能化使得低频/高频、大功率信号/小功率信号、高输出阻抗/低输出阻抗、大电流/小电流、模拟/数字电路,经常出现在同一个高封装密度电路板,设计者身处如此的环境必需面对前所未有的设计思维挑战,例如高稳定性电路与吵杂(noisy)性电路为邻时,如果未将噪讯入侵高稳定性电路的对策视为设计重点,事后反复的设计变更往往成为无解的梦魇。模拟电路与高速数字电路混合设计也是如此,假设微小模拟信号增幅后再将full scale 5V的模拟信号,利用10bit A/D转换器转换成数字信号,由于分割幅宽祇有4.9mV,因此要正确读取该电压level并非易事,结果造成10bit以上的A/D转换器面临无法顺利运作的窘境。另一典型实例是使用示波器量测某数字电路基板两点相隔10cm的ground电位,理论上ground电位应该是零,然而实际上却可观测到4.9mV数倍甚至数十倍的脉冲噪讯(pulse noise),如果该电位差是由模拟与数字混合电路的grand所造成的话,要测得4.9 mV的信号根本是不可能的事情,也就是说为了使模拟与数字混合电路顺利动作,必需在封装与电路设计有相对的对策,尤其是数字电路switching时,ground vance noise不会入侵analogue ground的防护对策,同时还需充分检讨各电路产生的电流回路(route)与电流大小,依此结果排除各种可能的干扰因素。以上介绍的实例都是设计模拟与数字混合电路时经常遇到的瓶颈,如果是设计12bit以上A/D转换器时,它的困难度会更加复杂。
上传时间: 2014-02-12
上传用户:wenyuoo
本文将接续介绍电源与功率电路基板,以及数字电路基板导线设计。宽带与高频电路基板导线设计a.输入阻抗1MHz,平滑性(flatness)50MHz 的OP增幅器电路基板图26 是由FET 输入的高速OP 增幅器OPA656 构成的高输入阻抗OP 增幅电路,它的gain取决于R1、R2,本电路图的电路定数为2 倍。此外为改善平滑性特别追加设置可以加大噪讯gain,抑制gain-频率特性高频领域时峰值的R3。图26 高输入阻抗的宽带OP增幅电路图27 是高输入阻抗OP 增幅器的电路基板图案。降低高速OP 增幅器反相输入端子与接地之间的浮游容量非常重要,所以本电路的浮游容量设计目标低于0.5pF。如果上述部位附着大浮游容量的话,会成为高频领域的频率特性产生峰值的原因,严重时频率甚至会因为feedback 阻抗与浮游容量,造成feedback 信号的位相延迟,最后导致频率特性产生波动现象。此外高输入阻抗OP 增幅器输入部位的浮游容量也逐渐成为问题,图27 的电路基板图案的非反相输入端子部位无full ground设计,如果有外部噪讯干扰之虞时,接地可设计成网格状(mesh)。图28 是根据图26 制成的OP 增幅器Gain-频率特性测试结果,由图可知即使接近50MHz频率特性非常平滑,-3dB cutoff频率大约是133MHz。
标签: PCB
上传时间: 2013-11-09
上传用户:z754970244
SL811开发资料_包含源程序_电路图_芯片资料:SL811HS Embedded USB Host/Slave Controller.The SL811HS is an Embedded USB Host/Slave Controller capable of communicate with either full-speed or low-speed USB peripherals. The SL811HS can interface to devices such as microprocessors, microcontrollers, DSPs, or directly to a variety of buses such as ISA, PCMCIA, and others. The SL811HS USB Host Controller conforms to USB Specification 1.1.The SL811HS USB Host/Slave Controller incorporates USB Serial Interface functionality along with internal full-/low-speed transceivers.The SL811HS supports and operates in USB full-speed mode at 12 Mbps, or at low-speed 1.5-Mbps mode.The SL811HS data port and microprocessor interface provide an 8-bit data path I/O or DMA bidirectional, with interrupt support to allow easy interface to standard microprocessors or microcontrollers such as Motorola or Intel CPUs and many others. Internally,the SL811HS contains a 256-byte RAM data buffer which is used for control registers and data buffer.The available package types offered are a 28-pin PLCC (SL811HS) and a 48-pin TQFP package (SL811HST-AC). Both packages operate at 3.3 VDC. The I/O interface logic is 5V-tolerant.
上传时间: 2013-12-22
上传用户:a82531317
PhpDig is a search engine written in PHP that uses a MySQL database backend. It features indexing of both static and dynamic pages, spidering of almost all links in HTML content, in hrefs, areamaps, and frames, and full text indexing. The search results appearence is skin-able, using a very simple templates system. PhpDig是一个用PHP编写的搜索引擎,它使用MySQL数据库后台。它的功能有静态和动态页面索引,在HTML内容中用hrefs, areamaps,和frames以及全文本索引构成所有的链接网。搜索结果的外观是可定制外观的,使用一个非常简单的模板系统。
标签: database features indexing backend
上传时间: 2014-01-03
上传用户:haohaoxuexi
Java Clock is a FREE Java applet used to display a clock on your Web pages. You can display either analog or digital clock. The full source code of this applet is also available (visit my home page to download it). You may use this applet on your Web pages WITHOUT paying me fee or royalty as long as credit is given (a link to my home page is enough).
标签: display Java applet either
上传时间: 2014-01-12
上传用户:woshiayin
The Small C compiler translates a subset of the C language into assembly language. It runs under PC/MS-DOS 2.1 and later. Small C is compatible with the Microsoft and Small Mac assemblers. Small C takes full advantage of the ability of these assemblers to generate relocatable object code, to maintain libraries of relocatable modules, and to link separately compiled program modules. It supports a small memory model with one code and one data/stack segment.
标签: language translates compiler assembly
上传时间: 2015-04-08
上传用户:Avoid98
CC386 is a general-purpose 32-bit C compiler. It is not an optimizing compiler but given that the code generation is fairly good. There are two versions one is for MSDOS/DPMI and one is for Win32. The Win32 version has a full-blown IDE capable of editing, building, and debugging windows programs included with it. However at this time debugging support for MSDOS is rudimentary at best and there is no IDE for DOS. the newest version, support windows.
标签: compiler general-purpose optimizing given
上传时间: 2015-04-12
上传用户:gtzj