单片机的介绍
单片机也被称为微控制器（MCU Unit），常用英文字母的缩写MCU表示单片机，它最早是被用在工业控制领域。单片机由芯片内仅有CPU的专用处理器发展而来。最早的设计理念是通过将大量外围设备和CPU集成在一个芯片中，使计算机系统更小，更容易集成进复杂的而对体积要求严格的控制设备当中。INTEL的Z80是最早按照这种思想设计出的处理器，从此以后，单片机和专用处理器的发展便分道扬镳。
单片机,它不是完成某一个逻辑功能的芯片,而是把一个计算机系统集成到一个芯片上。概括的讲：一块芯片就成了一台计算机。它的体积小、质量轻、价格便宜、为学习、应用和开发提供了便利条件。同时，学习使用单片机是了解计算机原理与结构的最佳选择。
单片机是靠程序运行的，并且可以修改。通过不同的程序实现不同的功能，尤其是一些特殊的功能，这是别的器件需要费很大力气才能做到的，有些则是花大力气也很难做到的。一个不是很复杂的功能要是用美国50年代开发的74系列，或者60年代的CD4000系列这些纯硬件来搞定的话，电路一定是一块大PCB板。但是如果要是用美国70年代成功投放市场的系列单片机，结果就会有天壤之别。只因为单片机的通过你编写的程序可以实现高智能，高效率，以及高可靠性。
二十世纪跨越了三个“电”的时代，即电气时代、电子时代和电脑时代。不过，这种电脑，通常是指个人计算机，简称PC机。它由主机、键盘、显示器等组成。还有一类计算机，大多数人却不怎么熟悉。这种计算机就是把智能赋予各种机械的单片机。顾名思义，这种计算机的最小系统只用了一片集成电路，即可进行简单运算和控制。因为它体积小，通常都藏在被控机械的“肚子”里。它在整个装置中，起着有如人类头脑的作用，它出了毛病，整个装置就瘫痪了。现在，这种单片机的使用领域已十分广泛，如智能仪表、实时工控、通讯设备、导航系统、家用电器等。各种产品一旦用上了单片机，就能起到使产品升级换代的功效，常在产品名称前冠以形容词——“智能型”，如智能型洗衣机等。现在有些工厂的技术人员或其它业余电子开发者搞出来的某些产品，不是电路太复杂，就是功能太简单且极易被仿制。究其原因，可能就卡在产品未使用单片机或其它可编程逻辑器件上。
单片机历史
单片机诞生于20世纪70年代末，经历了SCM、MCU、SoC三大阶段。
SCM阶段
单片机主要是寻求最佳的单片形态嵌入式系统的最佳体系结构。“创新模式”获得成功，奠定了SCM与通用计算机完全不同的发展道路。在开创嵌入式系统独立发展道路上，Intel 公司功不可没。
MCU阶段
MCU即微控制器（Micro Controller Unit）主要的技术发展方向是：不断扩展满足嵌入式应用时，对象系统要求的各种外围电路与接口电路，突显其对象的智能化控制能力。它所涉及的领域都与对象系统相关，因此，发展MCU的重任不可避免地落在电气、电子技术厂家。从这一角度来看，Intel逐渐淡出MCU的发展也有其客观因素。在发展MCU方面，最著名的厂家当数Philips公司。
Philips公司以其在嵌入式应用方面的巨大优势，将MCS-51从单片微型计算机迅速发展到微控制器。因此，当我们回顾嵌入式系统发展道路时，不要忘记Intel和Philips的历史功绩。SoC阶段
单片机向MCU阶段发展的重要因素，就是寻求应用系统在芯片上的最大化解决.因此，专用单片机的发展自然形成了SoC化趋势。随着微电子技术、IC设计、EDA工具的发展，基于SoC的单片机应用系统设计会有较大的发展。因此，对单片机的理解可以从单片微型计算机、单片微控制器延伸到单片应用系统。
单片机的应用领域
目前单片机渗透到我们生活的各个领域，几乎很难找到哪个领域没有单片机的踪迹。因此，单片机的学习、开发与应用将造就一批计算机应用与智能化控制的科学家、工程师。单片机广泛应用大致可分如下几个范畴：
1.在智能仪器仪表上的应用
单片机具有体积小、功耗低、控制功能强、扩展灵活、微型化和使用方便等优点，广泛应用于仪器仪表中，结合不同类型的传感器，可实现诸如电压、功率、频率、湿度、温度、流量、速度、厚度、角度、长度、硬度、元素、压力等物理量的测量。采用单片机控制使得仪器仪表数字化、智能化、微型化，且功能比起采用电子或数字电路更加强大。例如精密的测量设备（功率计，示波器，各种分析仪）。
2.在工业控制中的应用
用单片机可以构成形式多样的控制系统、数据采集系统。
3.在家用电器中的应用
可以这样说，现在的家用电器基本上都采用了单片机控制，从电饭褒、洗衣机、电冰箱、空调机、彩电、其他音响视频器材、再到电子秤量设备，五花八门，无所不在。
4.在计算机网络和通信领域中的应用
现代的单片机普遍具备通信接口，可以很方便地与计算机进行数据通信，为在计算机网络和通信设备间的应用提供了极好的物质条件，现在的通信设备基本上都实现了单片机智能控制，从手机，电话机、小型程控交换机、楼宇自动通信呼叫系统、列车无线通信、再到日常工作中随处可见的移动电话，集群移动通信，无线电对讲机等。
5.单片机在医用设备领域中的应用
单片机在医用设备中的用途亦相当广泛，例如医用呼吸机，各种分析仪，监护仪，超声诊断设备及病床呼叫系统等等。
6.在各种大型电器中的模块化应用
某些专用单片机设计用于实现特定功能，从而在各种电路中进行模块化应用，而不要求使用人员了解其内部结构。如音乐集成单片机，看似简单的功能，微缩在纯电子芯片中（有别于磁带机的原理），就需要复杂的类似于计算机的原理。如：音乐信号以数字的形式存于存储器中（类似于ROM），由微控制器读出，转化为模拟音乐电信号（类似于声卡）。在大型电路中，这种模块化应用极大地缩小了体积，简化了电路，降低了损坏、错误率，也方便于更换。
7.单片机在汽车设备领域中的应用
单片机在汽车电子中的应用非常广泛，例如汽车中的发动机控制器，基于CAN总线的汽车发动机智能电子控制器，GPS导航系统，abs防抱死系统，制动系统等等。此外，单片机在工商，金融，科研、教育，国防航空航天等领域都有着十分广泛的用途。
单片机学习应用的六大重要部分
一、总线：Bus
我们知道，一个电路总是由元器件通过电线连接而成的，在模拟电路中，连线并不成为一个问题，因为各器件间一般是串行关系，各器件之间的连线并不很多，但计算机电路却不一样，它是以微处理器为核心，各器件都要与微处理器相连，各器件之间的工作必须相互协调，所以需要的连线就很多了，如果仍如同模拟电路一样，在各微处理器和各器件间单独连线，则线的数量将多得惊人，所以在微处理机中引入了总线的概念，各个器件共同享用连线，所有器件的8根数据线全部接到8根公用的线上，即相当于各个器件并联起来，但仅这样还不行，如果有两个器件同时送出数据，一个为0，一个为1，那么，接收方接收到的究竟是什么呢？这种情况是不允许的，所以要通过控制线进行控制，使器件分时工作，任何时候只能有一个器件发送数据（可以有多个器件同时接收）。器件的数据线也就被称为数据总线，器件
所有的控制线被称为控制总线。在单片机内部或者外部存储器及其它器件中有存储单元，这些存储单元要被分配地址，才能使用，分配地址当然也是以电信号的形式给出的，由于存储单元比较多，所以，用于地址分配的线也较多，这些线被称为地址总线。
二、数据、地址、指令：
之所以将这三者放在一起，是因为这三者的本质都是一样的——数字，或者说都是一串…0?和…1?组成的序列。换言之，地址、指令也都是数据。指令：由单片机芯片的设计者规定的一种数字，它与我们常用的指令助记符有着严格的一一对应关系，不可以由单片机的开发者更改。地址：是寻找单片机内部、外部的存储单元、输入输出口的依据，内部单元的地址值已由芯片设计者规定好，不可更改，外部的单元可以由单片机开发者自行决定，但有一些地址单元是一定要有的（详见程序的执行过程）。数据：这是由微处理机处理的对象，在各种不同的应用电路中各不相同，一般而言，被处理的数据可能有这么几种情况：
1.地址（如MOV DPTR，1000H），即地址1000H送入DPTR。
2.方式字或控制字（如MOV TMOD，#3），3即是控制字.
3.常数（如MOV TH0，#10H）10H即定时常数。
4.实际输出值（如P1口接彩灯，要灯全亮，则执行指令：MOV P1，#0FFH，要灯全暗，则执行指令：MOV P1，#00H）这里0FFH和00H都是实际输出值。又如用于LED的字形码，也是实际输出的值。
理解了地址、指令的本质，就不难理解程序运行过程中为什么会跑飞，会把数据当成指令来执行了。
三、P0口、P2口和P3的第二功能用法：
初学时往往对P0口、P2口和P3口的第二功能用法迷惑不解，认为第二功能和原功能之间要有一个切换的过程，或者说要有一条指令，事实上，各端口的第二功能完全是自动的，不需要用指令来转换。如P3.6、P3.7分别是WR、RD信号，当单片机外接RAM或有外部I/O 口时，它们被用作第二功能，不能作为通用I/O口使用，只要一微处理机一执行到MOVX指令，就会有相应的信号从P3.6或P3.7送出，不需要事先用指令说明。事实上…不能作为通用I/O口使用?也并不是…不能?而是（使用者）…不会?将其作为通用I/O口使用。你完全可以在指令中按排一条SETB P3.7的指令，并且当单片机执行到这条指令时，也会使P3.7变为高电平，但使用者不会这么去做，因为这通常会导致系统的崩溃。
四、程序的执行过程：
单片机在通电复位后8051内的程序计数器（PC）中的值为…0000?，所以程序总是从…0000?单元开始执行，也就是说：在系统的ROM中一定要存在…0000?这个单元，并且在…0000?单元中存放的一定是一条指令。
五、堆栈：
堆栈是一个区域，是用来存放数据的，这个区域本身没有任何特殊之处，就是内部RAM 的一部份，特殊的是它存放和取用数据的方式，即所谓的…先进后出，后进先出?，并且堆栈有特殊的数据传输指令，即…PUSH?和…POP?，有一个特殊的专为其服务的单元，即堆栈指针SP，每当执一次PUSH指令时，SP就（在原来值的基础上）自动加1，每当执行一次POP 指令，SP就（在原来值的基础上）自动减1。由于SP中的值可以用指令加以改变，所以只要在程序开始阶段更改了SP的值，就可以把堆栈设置在规定的内存单元中，如在程序开始时，用一条MOV SP，#5FH指令，就是把堆栈设置在从内存单元60H开始的单元中。一般程序的开头总有这么一条设置堆栈指针的指令，因为开机时，SP的初始值为07H，这样就使堆栈从08H单元开始往后，而08H到1FH这个区域正是8031的第二、三、四工作寄存器区，经常要被使用，这会造成数据的混乱。不同作者编写程序时，初始化堆栈指令也不完全相同，这是作者的习惯问题。当设置好堆栈区后，并不意味着该区域成为一种专用内存，它还是可以象普通内存区域一样使用，只是一般情况下编程者不会把它当成普通内存用了。
六、单片机的开发过程：
这里所说的开发过程并不是一般书中所说的从任务分析开始，我们假设已设计并制作好硬件，下面就是编写软件的工作。在编写软件之前，首先要确定一些常数、地址，事实上这些常数、地址在设计阶段已被直接或间接地确定下来了。如当某器件的连线设计好后，其地址也就被确定了，当器件的功能被确定下来后，其控制字也就被确定了。然后用文本编辑器（如EDIT、CCED等）编写软件，编写好后，用编译器对源程序文件编译，查错，直到没有语法错误，除了极简单的程序外，一般应用仿真机对软件进行调试，直到程序运行正确为止。运行正确后，就可以写片（将程序固化在EPROM中）。在源程序被编译后，生成了扩展名为HEX的目标文件，一般编程器能够识别这种格式的文件，只要将此文件调入即可写片。七．单机片发展趋势
目前市场上单片机可以说是百花齐放，百家争鸣的时期，世界上各大芯片制造公司都推出了自己的单片机，从8位、16位到32位，数不胜数，应有尽有，有与主流C51系列兼容的，也有不兼容的，但它们各具特色，互成互补，为单片机的应用提供广阔的天地。纵观单片机的发展过程，可以预示单片机的发展趋势，大致可以分为：
1.低功耗CHMOS化
MCS-51系列的8031推出时的功耗达630mW，而现在的单片机普遍都在100mW左右，随着对单片机的功耗要求越来越低，现在的各个单片机制造商基本都采用了CMOS(互补金属氧化物半导体工艺)。像80-C51就采用了HMOS(即高密度金属氧化物半导体工艺)和CHMOS(互补高密度金属氧化物半导体工艺)。CMOS虽然功耗较低，但由于其物理特征决定其工作速度不够高，而CHMOS则具备了高速和低功耗的特点，这些特征，更适合于在要求低功耗像电池供电的应用场合。所以这种工艺将是今后一段时期单片机发展的主要途径。2.微型单片化
现在常规的单片机普遍都是将中央处理器(CPU)、随机存取数据存储(RAM)、只读程序存储器(ROM)、并行和串行通信接口，中断系统、定时电路、时钟电路集成在一块单一的芯片上，增强型的单片机集成，例如A/D转换器、PMW(脉宽调制电路)、WDT(看门狗)。有些单片机将LCD(液晶)驱动电路都集成在单一的芯片上，这样单片机包含的单元电路就更多，功能就越强大。甚至厂商还可以根据用户的要求量身定做，制造出具有自己特色的单片机芯片。
此外，现在的产品普遍要求体积小、重量轻，这就要求单片机除了功能强和功耗低外，还要求其体积要小。现在的许多单片机都具有多种封装形式，其中SMD(表面封装)越来越受欢迎，使得由单片机构成的系统正朝微型化方向发展。
3.主流与多品种共存
现在虽然单片机的品种繁多，各具特色，但仍以80C51为核心的单片机占主流，兼容其结构和指令系统的有PHILIPS公司的产品，ATMEL公司的产品和中国台湾的Winbond系列单片机。所以C8051为核心的单片机占据了半壁江山。而Microchip公司的PIC精简指令集(RISC)也有着强劲的发展势头，中国台湾的HOLTEK公司近年的单片机产量与日俱增，与其低价质优的优势，占据一定的市场分额。此外还有MOTOROLA公司的产品是日本几大公司的专用单片机。在一定的时期内，这种情形将得以延续，将不存在某个单片机一统天下的垄断局面，走的是依存互补，相辅相成、共同发展的道路。
the Introduction of MCU
Single chip microcomputer is also known as micro-controller (Micro-Controller Unit), commonly used letters of the acronym MCU ,which was first used in industrial control. MCU developed from a dedicated processor which has only a CPU. The first design is that integrating large number of peripherals and CPU into a chip makes the computer system smaller, and then the system is more easily integrated into a complex device which has strict demand on the volume. Intel's Z80 is the first designed in accordance with this idea processor. Then part company each going his own way.
MCU is not the chip that completes a certain logic function , but a chip which a computer system is integrated into . Generally speaking, a chip becomes a computer. Its small volume, light weight and low price provide the convenience for learning, application and development . At the same time, learn to use MCU is the best way to know the principle and structure of computer.
MCU is running by programs ,which can be modified. Through different programs achieve different functions, especially some unique functions, is hardly to complete to other devices even if great efforts be done.If a not very complex function is invented by pure hardware such as the 74 series which was developed in the 50's in the United States or the 60's CD4000 series , then the circuit must be a large PCB board! But if the SCM that United States putted in in the 70's is used, the result will be a drastic change! Just because your programs compiled by MCU can achieve high intelligence, high efficiency and high reliability!
The twentieth century witnessed the three "electric" eras, that is the age of electricity, the age of electron and now the age of computer. However, this kind of computer, usually refers to the personal computer, called for short as PC machine. It consists of main engine, a keyboard, a monitor, etc . There is a kind of computer, which most people are not very familiar with. This computer gives intelligence to all kinds of mechanical micro-controller . As the name suggests, this computer's minimum system only has a piece of integrated circuit and can do simple operation and control. Because of its small size, it is usually hidden in the "belly" of machine which is controlled. It is important to the entire device just like the human mind to a man .If it goes wrong, the whole device will be paralyzed. Now, the use fields of MCU has been very widely, such as intelligent instrument, real-time industrial control, communications equipment, navigation system, household electric appliances, etc. All kinds of products once used the single-chip microcomputer can have the effect of the upgrading of products, whose name will be added the word adjective - "intelligent", such as intelligent washing machine, etc. Now some factory technical personnel or other amateur electronics developers invent certain products, whose circuit is too complicated or function is too simple and easily be imitated. It is probably due to the lack of MCU or other programmable logic devices .
the History of MCU
Single chip machine was born in the 1970 s, experienced SCM, MCU and SoC three stages.
the Stage of SCM
MCU is mainly to seek the best system structure of the best single chip morphology of the embedded system . The success of the "Innovation model" lays the foundation for different completely roads of development between SCM and general computer. In the independent development road of embedded system , Intel company play an important role.
the Stage of MCU
The main technology development direction of MCU is expanding the various peripheral circuit and interface circuit demanded by target system in terms of meeting embedded application, which can show the object's intelligent control ability. The domains of MCU involved relate to target system .Therefore, the burden of the development of MCU inevitably fall in electrical and electronic technology manufacturers. From this point , Intel also has its objective factors to give up the development of MCU gradually. In the development of MCU, the most famous manufacturer is Philips .
Philips developed MCS - 51 from SCM to MCU by its great advantage in embedded applications . Therefore, when we review the embedded system development road, we should not forget the historical merit of Intel and Philips.
the Stage of SoC
The important factor of SCM develop into MCU is to seek application system on a chip in the maximization of solution.Therefore, special MCU development naturally formed the trend to SoC. With the development of microelectronics technology, IC design and EDA tools,the design of MCU application system based on the SoC will have greater development. Therefore, the understanding to MCU can extend from single chip microcomputer and single chip micro controller to single chip application system.
the Application Fields of MCU
At present MCU permeates every aspect of our lives.It is hard to find there is no trace of the MCU in some certain fields. Therefore, the study, exploitation and application of MCU will create a number of scientists and engineers who are engaged in computer applications and intelligent control .The applications of MCU generally can be divided into the following several categories: 1.the Application of MCU in Intelligent Instruments
MCU has small volume, low power consumption, strong control function,agile expansion, miniaturization and use convenience etc, which are widely used in instruments, combined with different types of sensors, which can realize such as voltage, power, frequency, humidity, temperature, flow, speed, thickness, Angle, length, hardness, elements, pressure measurement of physical quantities. Using MCU control makes the instruments digital, intelligent, miniaturization. Compared with the function of electronic or digital circuit,MCU is more powerful. Such as the precision of the measurement equipment (power meter, oscilloscope, various analyzer).
2.the Application of MCU in Industrial Control
By using MCU we can constitute a variety of control systems and data acquisition systems.
3.the Application of MCU in Household Appliances
It can be said that now the household appliances are basically using the MCU control, which are multifarious and omnipresent from the electric rice cooked, washing machines, refrigerators, air conditioning, color TV, and other audio video equipment, to scale quantity equipment.
4.the Applications of MCU in Computer Network and Communication
Modern MCU generally have the communication interface,through which MCU can has data communication with computers easily,which provides good material conditions for applications between computer network and communication equipments.Now all the communication equipments basically realize the MCU intelligent control, which can be seen from the mobile phone, telephone, small program-controlled switches, building automatic communication call system, train wireless communication to the general mobile phone, cluster mobile communications, radios, which can be seen everywhere.
5.the Application of MCU in the Field of Medical Equipment
The uses of MCU in the medical equipment also is quite widespread, such as medical breathing machine, all kinds of analyzer, monitor, ultrasonic diagnostic equipment and sickbed calling system, etc.
6.the Modular Application of MCU in All Kinds of Large-scale Electric Appliance
Some special single-chip microcomputer designed to achieve specific functions in various circuit in modular application, which do not require people to understand its internal structure. Such as integrated music MCU, which looks like simple function, miniature in pure electronic chip (different from the tape machine principle), which needs complex principle as the computer has. For example, music signal in digital form stored in memory (similar to the ROM), composed of micro controller, read into analog music signal (similar to the sound card). In the large circuit, this modular application greatly reduce volume, simplify the circuit and reduce the damage, error rate,
and convenient to change.
7.the Applications of MCU in Automotive Equipment
The application of MCU in the automotive electronics is very widespread, such as the car engine controller based on CAN bus, car engine intelligent electronic controller, GPS navigation system, abs anti-lock system, braking system, etc. In addition, the use of MCU in business, finance, scientific research, education, defense aerospace and other fields is also widespread.
the Six Important Parts of the Study and Application of MCU
1.BUS
We know that a circuit contains lots of components which connected by wires .In analog circuits, the attachment is not a problem, because the device is usually between serial relationship between each device, and there is not many wires between components. However ,the computer circuit is different, it has a microprocessor as the core, with which the devices need to be connected .The works between devices must be concerted, thus we need lots of wires . If we link wires as analog circuit in which the microprocessor and the device have their own wires, the amounts of wires will be amazing .Therefore we introduced the concept of bus each device Shared in micro processor . All the eight roots of components are linked to eight public lines, that is each device parallel up.Everything is ok ? Not yet. If there are two devices sending data at the same time , a 0, a 1, so,whose data will be received ? This kind of situation is not allowed, so we should control devices work at different time through the line when there is only one device sending data (can have multiple devices at the same time receive). The data line of the components is called data bus and the control line is called the control bus.There is a storage unit that will be assigned address which is the premise that MCU can work in the internal or external memory of MCU and other devices. Distributing address, of course, is in the form of electrical signals.The amounts of the line used to distribute address and called the address bus is massive because the storage unit is more.
2.Data, address, instruction
We put them together just because the nature of these three are the same - digital, or are sequences composed by a bunch of "0" and "1" . In other words, address and instruction are also data. Instruction is a kind of digital that the MCU chip designer prescribed, which has a strict one-to-one correspondence relationship with our common instruction mnemonic and can't be changed by single-chip microcomputer developers. Address is the basis that MCU looks for internal and external storage unit and input/output port . Internal unit address value is the provisions of the chip designers and can not be changed,and external unit can be made by MCU developers themselves, but some address unit is necessary (see program execution). Data is the microprocessor processing object,which is not identical in different application circuits.In general, the processed data may have such several ways:
(1)Address (such as MOV DPTR, 1000 h), the address 1000 h into DPTR
(2)Way word or control word (such as MOV TMOD, # 3), 3 is control word
(3) Constant (such as MOV TH0, # 10 h) and 10h is time constant
(4)The actual output values (such as P1 mouth pick lights to light all bright, it is executed instruction: MOV P1, # 0 FFH to light all dark, then execute instruction: MOV P1, # 00 h) here 0 FFH and 00 h is the actual output value. And as for the LED font code, also is the actual output value
After understanding the address and the essence of instruction, it's not hard to understand why a program will go wrong in the process of program and treat the data as the instruction to be executed.
3.P0, P2 and P3 and Their Second Function Usage:
The second function usage of P0 , P2 and P3 will puzzles beginners ,who think that there is a switching process or an instruction between the second function and the primary function .In fact, the port of the second function is completely automatic and do not need to use the instructions to converse. Such as P3.6 is WR signal and P3.7 is RD signal, when MCU joint RAM or external I/O port, they are used as the second function and not as a general purpose I/O port to use.Then as long as microprocessor execute MOVX instruction, there will be a corresponding signal from P3.6 or P3.7 sent out and do not need to illustrate with instruction. In fact, "not as a general purpose I/O port to use "is not" can't "but (users) 'not' as a general purpose I/O port to use. You can arrange the order in a SETB P3.7's instructions. And when MCU execute this instruction, it also can make P3.7 into a high level, but users will not do it, because it usually lead to the collapse of the system.
4.Program Execution
After the reset of Microcomputer in the power, the value of the program counter (PC) will be '0000', so program always began to carry out from '0000' unit , that is,the '0000' unit is essential in the ROM of system , and in the '0000' unit of storage must be an instruction.
5.Stack
The stack is an area which is used for storing data. The region itself does not have any special place but its store and access data mode that 'the first in,the last out ;the last in ,the first out 'and is a part of the internal RAM.Additionally, stack has special data transmission instruction, namely "PUSH" and "POP", there is a special designed for the service unit, namely the stack pointer SP, when executing a PUSH instruction, SP (in the original on the basis of value) to be automatic add 1; when executing a POP instruction, SP (in the original on the basis of value) to be automatic minus 1. Because the SP value can be changed by using instruction , so as long as you change the value of SP at the start of the program, the stack can be setted in the prescribed memory unit.For example,at the beginning of the program, with a MOV SP, # 5Fh instruction, then the program will execute from the memory unit whose address is 60h. The beginning of the general procedure always have such a setting stack pointer's instructions, because when the MCU is switched on, the initial value for the SP is 07h, thus make the stack start at 08h unit.However ,the area from 08h to 1Fh is 8031 the second, third, and fourth working registers area which is often to be used, which can cause data chaos. Different authors write different initialize stack instructions , which is the habit of the problem.After setting stack area, it does not mean that the area become a special memory and can still like a common memory area use, but usually the designer of the program will not use it as a common memory .
6.the Development Process of MCU
What we say about the development process of MCU is not like the book said that we start the task with analysis first. We assume that we have designed and produced good hardware, and next is written work of the software .Before writing the software , the first step is to ascertain some constant and address, in fact, and these constant and address in the design phase has been directly or indirectly confirmed. After a device's connection is designed, its address will be confirmed, and after the function of the device is decided, the control word will be confirmed. Then using the text editor (such as EDIT, CCED, etc.) to write software, next using the compiler to compile the source program files and check errors until there is no grammar mistakes. We usually use software simulator for commissioning except simple programs until the programs run correctly .Then we can set program into the EPROM. After the source program is compiled and the HEX object files is generated,then general programmer can recognize this format files and we can set the programs into MCU.
7.the Development Trend of MCU
On the market at present the development trend of MCU can be said to be the period of flowers blossoming and schools of thought contending . In the world some big chip manufacturing companies have launched their own MCU, which vary from 8, 16 to 32 bit and countless and are compatible and not compatible with mainstream C51 series , but they have their special features and mutual into complementary,which provide great blueprint for the application of MCU.From the development process of MCU, we can predict the development trend of MCU, which can be roughly divided into three parts.
(1)Low Power Consumption CHMOS Trend
The power consumption of 8031 of MCS - 51 series was 630 MW , and now the MCU's power consumption generally is 100 MW.Now every MCU basic manufacturer use CMOS along with demand to MCU power consumption is more and more low (complementary metal oxide semiconductor process). For example the 80 - C51 had adopted HMOS (i.e. high density metal oxide semiconductor process) and CHMOS(complementary high-density metal oxide semiconductor process). Although the power consumption of CMOS is low, the working speed is not high because of its physical characteristics ,and CHMOS is with the characteristics of the high speed and low power consumption , which are more suitable for low power consumption in requirements as battery powered applications. So the process will be the main way to the development of the MCU for a period.
(2)Miniature Monolithic Trend
Now the conventional MCU generally is the integration on a chip ,which contains central processing unit (CPU), random access data memory (RAM), read only memory (ROM) program, parallel and serial communication interface, interrupt system, timing circuit, and clocking circuit ,which is the enhancement of the MCU integrated, such as A/D converter, PMW (pulse width modulation circuit) and WDT (big dog). Some MCU integrate LCD (liquid crystal) drive circuit on a single chip which contains lots of unit circuits and the function is strong. Even MCU can also be customized according to the user's requirements, manufacturers product the MCU which has its own characteristics.
In addition, the present products' universal demand are small volume and light weight, which requires the MCU's function is strong and MCU's power consumption is low and its volume is small. Many of the MCU now have a variety of packaging forms, including SMD (surface encapsulation) which has become more and more popular, make the system consisted by MCU develop into miniaturization.
(3)The Mainstream and Many Varieties Coexist
Now although MCU has lots of varieties and characteristics, still the 80c51 is the core of the mainstream MCU, with whose structure and command system PHILIPS company's products, ATMEL company's products and China Taiwan Winbond series micro-controller are compatible . So C8051 MCU as the core occupy deodorants. And Microchip company's PIC reduced instruction set (RISC) also has a strong momentum of development.In recent years China Taiwan HOLTEK company's increasing production of MCU with its low price and high quality advantage occupy a certain market share. In addition, MOTOROLA company's products is the specialized MCU of a few big Japanese companies . In a certain period of time, this kind of situation will continue and there won't be a monopoly situation that a certain MCU unify the whole world,but a situation that all kinds of MCU are seeking for dependent complement, supplement each other and common development.
外国语学院2018届毕业论文文献综述（示范） 一、研究背景 近来多篇论文中出现零翻译的提法（杜争鸣，2000；邱懋如，2001；刘明东，2002；袁斌业，2002a，2002b，2002c，2002d；石琳，2003；余清萍，2003；余清萍，秦傲松，2004；肖耀田，2004），但国内学者所编三本译学词典（林煌天，1997；孙迎春，1999；方梦之，2004）均未出现零翻译这一词条，国外三本词典/术语著作（Shuttleworth & Cowie，1997；Baker，1998；Delisle，2004）亦未收入这一条目，只有国内孙迎春（2001）编著的《汉英双向翻译学语林》收进了“零翻译（音译、形译之一种）zero translation”（58页）及“zero translation零翻译（音译、形译之一种）”（268页）两个条目，同时又有贾影（2002）反对零翻译提法，并认为承认不可译有“积极作用”。但零翻译现象确实存在，如DIY（自己动手），IQ（智商），EQ（情商），这些零翻译词汇经常在汉语中出现。英语中也有类似情况，如美国《时代》周刊中报道中国特色事物时经常使用拼音，如aizi(矮子)，pizi（痞子），shiganjia（实干家），yuan（缘）（王祥兵，2002），shuangying(双赢)，guanxi(关系)（顾静，2005）。 这些研究成果揭示了零翻译现象的存在，引进了零翻译的概念，促进了翻译理论概念的扩大，但是从发表的论文及孙迎春（2001）的这两个条目来看，各自运用的名称虽同（也有不同，如杜争鸣称为不译），但概念的内涵及外延均有出入，因此有必要探讨当前零翻译研究的问题并提出相应研究对策。 二、研究现状及不足 1. 定义不统一、模糊不清 传统翻译理论多把零翻译归结为“音译法”、“移译法”，只看到技巧层面的意义，如秦建栋（1999）讨论“英汉词汇空缺现象刍议”列举“音译法”、“移译法”，袁斌业（2001）论及“英语本族人音译汉语词汇的语用分析”，虽然看到“音译在我国只能用来翻译名词，而在国外则可以用来翻译包括名词在内的各种词语”，但未能从中提炼出零翻译的概念，实际上这里已包含有零翻译与音译的某些区别。 国内最早使用zero translation这一术语的是杜争鸣（2000），但他称之为“不译”，并分析了直译、意译与不译三种翻译策略。他不停留于策略本身，从跨文化交际的视角分析了三种策略的社会语言学与跨文化交际涵义，并看到了不译的三层文化含义。不译背后体现译者对于翻译目的的认识，“而翻译的目的必然直接或间接地反映反映译者本人对翻译的文化含义的意识与潜意识，反映他翻译时所采取的文化姿态与立场。”即翻译观的问题。但从术语的精确性来说
AT89C51外文翻译 Description The AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer with 4K bytes of Flash Programmable and Erasable Read Only Memory (PEROM). The device is manufactured using Atmel’s high density nonvolatile memory technology and is compatible with the industry standard MCS-51? instruction-set and pinout. The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with Flash on a monolithic chip, the Atmel AT89C51 is a powerful microcomputer which provides a highly flexible and cost effective solution to many embedded control applications. Features ? Compatible with MCS-51? Products ? 4K Bytes of In-System Reprogrammable Flash Memory – Endurance: 1,000 Write/Erase Cycles ? Fully Static Operation: 0 Hz to 24 MHz ? Three-Level Program Memory Lock ? 128 x 8-Bit Internal RAM ? 32 Programmable I/O Lines ? Two 16-Bit Timer/Counters ? Six Interrupt Sources ? Programmable Serial Channel ? Low Power Idle and Power Down Modes The AT89C51 provides the following standard features: 4K bytes of Flash,128 bytes of RAM, 32 I/O lines, two 16-bit timer/counters, a five vector two-level interrupt architecture, a full duplex serial port, on-chip oscillator and clock circuitry. In addition, the AT89C51 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port and interrupt system to continue functioning. The Power-down Mode saves the RAM contents but freezes the oscillator disabling all other chip functions until the next hardware reset.
理工学院 毕业设计外文资料翻译 专业：计算机科学与技术 姓名：马艳丽 学号： 12L0752218 外文出处：The Design and Implementation of 3D Electronic Map of Campus Based on WEBGIS 附件： 1.外文资料翻译译文；2.外文原文。
附件1：外文资料翻译译文 基于WebGIS的校园三维电子地图的设计与实现 一．导言 如今，数字化和信息化是当今时代的主题。随着信息革命和计算机科学的发展，计算机技术已经渗透到科学的各个领域，并引起了许多革命性的变化，在这些科目，古代制图学也不例外。随着技术和文化的不断进步，地图变化的形式和内容也随之更新。在计算机图形学中，地理信息系统（GIS）不断应用到Web，制作和演示的传统方式经历了巨大的变化，由于先进的信息技术的发展，地图的应用已经大大延长。在这些情况下，绘图将面临广阔的发展前景。电子地图是随之应运而生的产品之一。随着计算机技术，计算机图形学理论，遥感技术，航空摄影测量技术和其他相关技术的飞速发展。用户需要的三维可视化，动态的交互性和展示自己的各种地理相关的数据处理和分析，如此多的关注应支付的研究三维地图。东北石油大学及其周边地区的基础上本文设计并建立三维电子地图。 二．系统设计 基于WebGIS的校园三维电子地图系统的具有普通地图的一般特性。通过按键盘上的箭头键（上，下，左，右），可以使地图向相应的方向移动。通过拖动鼠标，可以查看感兴趣的任何一个地方。使用鼠标滚轮，可以控制地图的大小，根据用户的需求来查看不同缩放级别的地图。在地图的左下角会显示当前鼠标的坐标。在一个div层，我们描绘了一个新建筑物的热点，这层可以根据不同的地图图层的显示，它也可以自动调整。通过点击热点，它可以显示热点的具体信息。也可以输入到查询的信息，根据自己的需要，并得到一些相关的信息。此外，通过点击鼠标，人们可以选择检查的三维地图和卫星地图。 主要功能包括： ?用户信息管理：检查用户名和密码，根据权限设置级别的认证，允许不同权限的用户通过互联网登录系统。 ?位置信息查询：系统可以为用户提供模糊查询和快速定位。
文献综述 大学生时间管理研究——以郑州大学西亚斯国际学院为例 姓名：代永寒学号：20091211205 专业：工商管理班级：工本2班 史蒂芬?柯维的《要事第一》 “要事第一”，顾名思义是指重要的主要的事情要放在第一时间去完成。而在实际工作中我们往往是将认为急迫的紧要的事情放在第一时间完成； 本书通过四个象限来告诉我们如何区分事情的紧急性与重要性，从而告诉我们在平常的工作中应怎样去区分事情属轻属重，以及造成事情紧急性的原因，在平常工作中要注意哪些方面以避免出现紧急事件的情况。 第一象限包括四点：A危机 B 急迫的问题C最后期限迫近的项目 D 会议准备工作等。第一象限显得紧迫与重要，但我们要知道形成第一象限的紧迫与重要主要是因被延误及没有进行计划与预测及计划所致。第二象限包含准备工作、预防、价值、筹划、建立关系、真正的再创造与赋予能力。第二象限属于质量象限，属于重要但不紧迫的事情，但我们必须要去做，因只有这样才能避免出现第一象限包含的情况。第三象限包含干扰、电话；邮件、报告；某些会议；很多临近、急迫的事情及很多流行的活动。第三象限包括“紧急但不重要的事情”，而事实上它易给人造成假象，从而形成第一象限情况。第四象限包含琐事、打发时间的工作、某些电话，解闷，“逃避”行为、无关紧要的邮件及过多地看电视；第四象限属于既不紧急也不重要的事情，它是浪费象限，第四象限中的行为是堕落行为。这四个象限告诉我们如果在办事过程中不是以重要性而是以紧要性为出发点，就会出现第一第三甚至第四象限的情况，在平常的工作中，我们要加以区分，日常工作生活中往往事情越是紧迫，反而说明事情越不重要！像最近存货系统因急着想能早日上线，在运作过程中被卡住，故一心想着去解决软件中存在的问题，而忽略了与其他人员的沟通协调，存货上软件固然重要，但与公司整体运作相比就稍显其次，没合理分配其他人员手头事项，这样会导致其他问题的增多，从而会出现第一第三象限甚至于第四象限的浪费情况。 “要事第一”，告诉我们在日常的工作与生活中要从以下方面着手加以区分、
Single chip brief introduction The monolithic integrated circuit said that the monolithic micro controller, it is not completes some logical function the chip, but integrates a computer system to a chip on. Summary speaking: A chip has become a computer. Its volume is small, the quality is light, and the price cheap, for the study, the application and the development has provided the convenient condition. At the same time, the study use monolithic integrated circuit is understands the computer principle and the structure best choice. The monolithic integrated circuit interior also uses with the computer function similar module, SCM basic component is a central processing unit (CPU in the computing device and controller), read-only memory (usually expressed as a ROM), read-write memory (also known as Random Access Memory MRAM is usually expressed as a RAM) , input / output port (also divided into parallel port and serial port, expressed as I / O port), and so composed. In fact there is also a clock circuit microcontroller, so that during operation and control of the microcontroller, can rhythmic manner. In addition, there are so-called "break system", the system is a "janitor" role, when the microcontroller control object parameters that need to be intervention to reach a particular state, can after this "janitor" communicated to the CPU, so that CPU priorities of the external events to take appropriate counter-measures. what is different is its these part performance is opposite our home-use computer weak many, but the price is also low, generally does not surpass 10 Yuan then ......Made some control electric appliance one kind with it is not the 'very complex work foot, We use now the completely automatic drum washer, the platoon petti-coat pipe: VCD and so on Inside the electrical appliances may see its form! ......It is mainly takes the control section the core part It is one kind of online -like real-time control computer, online -like is the scene control, needs to have the strong antijamming ability, the low cost, this is also and the off-line type computer (for instance home use PC,) main difference The monolithic integrated circuit is depending on the procedure, and may revise. Realizes the different function through the different procedure, particularly special unique some functions, this is other component needs to take the very big effort to be able to achieve, some are the flowered big strength is also very difficult to achieve. One is not the very complex function, if develops in the 50s with the US 74 series, or the 60s's CD4000 series these pure hardware do decides, the electric circuit certainly arc a big PCB board ! But if, if succeeded in the 70s with the US puts in the market the series monolithic integrated circuit, the result will have the huge difference. Because only the monolithic integrated circuit compiles through you the procedure may realize the high intelligence, high efficiency, as well as redundant reliability The CPU is the key component of a digital computer. Its purpose is to decode instruction received from memory and perform transfers, arithmetic, logic, and control operations with data stored in internal registers, memory, or I/O interface units. Externally, the CPU provides one or more buses for transferring instructions, data, and control information to and from components connected to it. A microcontroller is present in the keyboard and in the monitor in the generic computer; thus these components are also shaded. In such microcontrollers, the CPU may be quite different from those discussed in this chapter. The word lengths may be short, the number of registers small, and the instruction sets limited. Performance, relatively speaking, is poor, but adequate for the task. Most
附录 图像科学综述 近几年来，图像处理与识别技术得到了迅速的发展，现在人们己充分认识到图像处理和识别技术是认识世界、改造世界的重要手段。目前它己应用于许多领域，成为2l世纪信息时代的一门重要的高新科学技术。 1.图像处理与识别技术概述 图像就是用各种观测系统以不同形式和手段观测客观世界而获得的，可以直接或间接作用于人眼而产生视知觉的实体。科学研究和统计表明，人类从外界获得的信息约有75%来自于视觉系统，也就是说，人类的大部分信息都是从图像中获得的。 图像处理是人类视觉延伸的重要手段，可以便人们看到任意波长上所测得的图像。例如，借助伽马相机、x光机，人们可以看到红外和超声图像：借助CT可看到物体内部的断层图像；借助相应工具可看到立体图像和剖视图像。1964年，美国在太空探索中拍回了大量月球照片，但是由于种种环境因素的影响，这些照片是非常不清晰的，为此，美国喷射推进实验室(JPL)使用计算机对图像进行处理，使照片中的重要信息得以清晰再现。这是这门技术发展的重要里程碑。此后，图像处理技术在空间研究方面得到广泛的应用。 总体来说，图像处理技术的发展大致经历了初创期、发展期、普及期和实用化期4个阶段。初创期开始于20世纪60年代，当时的图像采用像素型光栅进行扫描显示，大多采用巾、大型机对其进行处理。在这一时期，由于图像存储成本高，处理设备造价高，因而其应用面很窄。20世纪70年代进入了发展期，开始大量采用中、小型机进行处理，图像处理也逐渐改用光栅扫描显示方式，特别是出现了CT和卫星遥感图像，对图像处理技术的发展起到了很好的促进作用。到了20世纪80年代，图像处理技术进入普及期，此时购微机已经能够担当起图形图像处理的任务。VLSL的出现更使得处理速度大大提高，其造价也进一步降低，极大地促进了图形图像系统的普及和应用。20世纪90年代是图像技术的实用化时期，图像处理的信息量巨大，对处理速度的要求极高。 21世纪的图像技术要向高质量化方面发展，主要体现在以下几点：①高分辨率、高速度，图像处理技术发展的最终目标是要实现图像的实时处理，这在移动
72页 Machine Tools Objectived. Machine tools are the main engines of the manufacturing industry. This chapter covers a few of the details that are common to all classes of machine tools discussed in this book. After completing the chapter, the reader will be able to >understand the classification of the various machine tools used in manufacturing industries. >identify the differences between generating and forming of surfaces. > identify various methods used to generate different types of surfaces. >distinguish between the different accuracies and surface finishes that are achievable with different machine tools. >understand the different components of the machine tools and their functions. >learn about the different support structures used in the machine tools. >understand the various actuation systems that are useful to generate the required surfaces. >Learn the different types of guideways used in the machine tools. >understand the work holding requirements. 3.1 INTRODUCTION The earliest known machine tools are the Egyptian foot-operated lathes.
1. About SCM It can be said across the twentieth century, the three "electric" era, that is, electrical era, the electronic age, and has now entered the computer age. However, such a computer, usually refers to the personal computer, referred to as PC. It consists of the host, keyboard, monitor etc.. Another type of computer, most people do not know how. This computer is to smart to give a variety of mechanical microcontroller (also known as micro-controller). As the name suggests, this computer system only used the smallest one IC, you can perform simple operations and control. Because of its small size, usually hidden in a charged mechanical "stomach" Lane. It is the entire device, like the human brain plays a role, it goes wrong, the whole device was paralyzed. Now, this MCU has a very wide field of use, such as smart meters, real-time industrial control, communications equipment, navigation systems, home appliances and so on. Once the microcontroller were using a variety of products, you can serve to upgrade the effectiveness of the product, often in the product name is preceded by the adjective - "smart", such as washing machines and so intelligent. At present, some technical personnel of factories or other amateur electronics developers to engage in out of certain products, not the circuit is too complex, that is, functions are too simple and easy to be copied. The reason may be stuck in the product without the use of a microcontroller or other programmable logic device. SCM basic component is a central processing unit (CPU in the computing device and controller), read-only memory (usually expressed as a ROM), read-write memory (also known as Random Access Memory MRAM is usually expressed as a RAM) , input / output port (also divided into parallel port and serial port, expressed as I / O port), and so composed. In fact there is also a clock circuit microcontroller, so that during operation and control of the microcontroller, can rhythmic manner. In addition, there are so-called "break system", the system is a "janitor" role, when the microcontroller control object parameters that need to be intervention to reach a particular state, can after this "janitor" communicated to the CPU, so that CPU priorities of the external events to take appropriate counter-measures. 单片机的简介 可以说，二十世纪跨越了三个“电”的时代，即电气时代、电子时代和现已进入的电脑时代。不过，这种电脑，通常是指个人计算机，简称PC机。它由主机、键盘、显示器等组成。还有一类计算机，大多数人却不怎么熟悉。这种计算机就是把智能赋予各种机械的单片机（亦称微控制器）。顾名思义，这种计算机的最小系统只用了一片集成电路，即可进行简单运算和控制。因为它体积小，通常都藏在被控机械的“肚子”里。它在整个装置中，起着有如人类头脑的作用，它出了毛病，整个装置就瘫痪了。
at89c52单片机简介 中英文资料对照外文翻译文献综述 A T89C52 Single-chip microprocessor introduction Selection of Single-chip microprocessor 1. Development of Single-chip microprocessor The main component part of Single-chip microprocessor as a result of by such centralize to be living to obtain on the chip，In immediate future middle processor CPU。Storage RAM immediately﹑memoy read ROM﹑Interrupt system、Timer /'s counter along with I/O's rim electric circuit awaits the main microcomputer section，The lumping is living on the chip。Although the Single-chip microprocessor r is only a chip，Yet through makes up and the meritorous service be able to on sees，It had haveed the calculating machine system property，calling it for this reason act as Single-chip microprocessor r minisize calculating machine SCMS and abbreviate the Single-chip microprocessor。 1976Year the Inter corporation put out 8 MCS－48Set Single-chip microprocessor computer，After being living more than 20 years time in development that obtain continuously and wide-ranging application。1980Year that corporation put out high performance MCS －51Set Single-chip microprocessor。This type of Single-chip microprocessor meritorous service capacity、The addressing range wholly than early phase lift somewhat，Use also comparatively far more at the moment。1982Year that corporation put out the taller 16 Single-chip microprocessor MCS of performance once
专业文献翻译 题目: AT89C51单片机的介绍 姓名: 学院: 专业: 电子信息科学与技术 班级: 班 学号: 指导教师: 职称: 20 年月日
原文： The Introduction of AT89C51 Description The AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer with 4K bytes of Flash programmable and erasable read only memory (PEROM). The device is manufactured using Atmel’s high-density nonvolatile memory technology and is compatible with the industry-standard MCS-51 instruction set. The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with Flash on a monolithic chip, the Atmel AT89C51 is a powerful microcomputer which provides a highly-flexible and cost-effective solution to many embedded control applications. Function characteristic The AT89C51 provides the following standard features: 4K bytes of Flash, 128 bytes of RAM, 32 I/O lines, two 16-bit timer/counters, one 5 vector two-level interrupt architecture, a full duplex serial port, one-chip oscillator and clock circuitry. In addition, the AT89C51 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port and interrupt system to continue functioning. The Power-down Mode saves the RAM contents but freezes the oscillator disabling all other chip functions until the next hardware reset. Pin Description VCC：Supply voltage. GND：Ground.
英文翻译 题目: 通过分析变压器中溶解气体而进行故障诊断的专家系统 姓名: 宋日成 学院: 工学院 专业: 自动化 班级: 自动化112 班学号: 32211218 指导教师: 陆静职称: 讲师 2015年3月14日 南京农业大学教务处制
An Expert System for Transformer Fault Diagnosis Using Dissolved Gas Analysis W. S. Chan ·Y. L. Xu ·X. L. Ding ·W. J. Dai Received: 9 November 2005 / Accepted: 11 August 2006 / Published online: 7 September 2006? Springer-Verlag 2006 Abstract In order to automate the transformer fault diagnosis, improve the accuracy of judgment, the introduction of artificial intelligence expert system fault diagnosis. The system is based on fuzzy reasoning confidence by observing the information, the use of knowledge to reach a conclusion. Test proved this method reduces the randomness of judgment, improved diagnosis. Keywords:Expert System Transformer Troubleshooting 1 Introduction The power transformer is a major apparatus in a power system, and its correct functioning is vital to system operations. In order to minimize system outages,many devices have evolved to monitor the serviceability of power transformers. These devices, such as, Buchholz relays or differential relays, respond only to a severe power failure requiring immediate removal of the transformer from service, in which case, outages are inevitable. Thus, preventive techniques for early detection faults to avoid outages would be valuable. In this way, analysis of the mixture of the faulty gases dissolved in insulation oil of power transformer has received worldwide recognition as an effective method for the detection of incipient faults. Many researchers and electrical utilities have reported on their experience and developed interpretative criteria on the basis of DGA. However, criteria tend to vary from utility to utility. Each approach has limitations and none of them has a firm mathematical description. Therefore, transformer diagnosis is still in the heuristic stage. For this reason, knowledge-based programming is a suitable approach to implement in such a diagnostic problem. Based on the interpretation of DGA, a prototype of an expert system for diagnosis of suspected transformer faults and their maintenance procedures is proposed. The significant source in this knowledge base is the gas ratio method. Some limitations of this approach are overcome by incorporating the diagnostic procedure and the synthetic expertise method. Furthermore, data bases adopted from TPCS gas records of transformers are incorporated into the expert system to increase the practical performance. Uncertainty of diagnosis is managed by using fuzzy set concepts. This expert system is constructed with rule based knowledge representation, since it can be expressed by experts. The expert system building tool, Knowledge Engineering System (KES), is used in the development of the knowledge system