單片機(jī)基礎(chǔ)外文翻譯

1、<p><b>　　畢業(yè)論文（設(shè)計）</b></p><p><b>　　外文翻譯</b></p><p>　　題 目： 單片機(jī)基礎(chǔ) </p><p>　　系部名稱： 信息工程系 專業(yè)班級：電氣工程及其自動化</p><p

2、>　　學(xué)生姓名： 陳龍 學(xué) 號： 200880884210 </p><p>　　指導(dǎo)教師： 崔丹丹 教師職稱： 講師 </p><p>　　2012 年 3月 7日</p><p><b>　　外文資料翻譯譯文</b></p><p

3、><b>　　單片機(jī)基礎(chǔ)</b></p><p>　　作為第二十世紀(jì)最偉大的發(fā)明，單片機(jī)是計算機(jī)和數(shù)字集成電路兩方面發(fā)展的結(jié)果。</p><p>　　計算機(jī)和集成電路在單片機(jī)中得到了充分的體現(xiàn)。一些廠家用他們區(qū)分程序內(nèi)存和數(shù)據(jù)內(nèi)存，如圖3-5A-1。依據(jù)同樣的原理廣泛的適用于一般目的的電腦和微電腦，使邏輯上沒有區(qū)別的程序和數(shù)據(jù)存儲在普林斯頓建筑，展示如圖3-5A

4、-2。</p><p>　　Fig.3-5A-1 哈佛模型</p><p>　　Fig.3-5A-2. 傳統(tǒng)的普林斯頓電腦</p><p><b>　　Reset</b></p><p>　　Interrupts</p><p><b>　　Power</b></

5、p><p>　　Fig3-5A-3. 主要特點微機(jī)</p><p>　　只讀存貯器ROM是通常的永久性的和非應(yīng)用程序易失性的存儲器。不少微機(jī)和單片機(jī)大批量應(yīng)用。因此，經(jīng)濟(jì)的設(shè)備制造要求的程序存儲器的，內(nèi)容是在制造期間永久性的刻錄在芯片中，這意味著需應(yīng)用嚴(yán)謹(jǐn)?shù)姆椒ǎ阂驗樾薷腞OM代碼不能發(fā)生在制造之后。這一發(fā)展過程可能涉及仿真,使用硬件仿真功能以及強(qiáng)大的軟件工具應(yīng)用于先進(jìn)的開發(fā)系統(tǒng)。</p

6、><p>　　一些制造商在其提供的設(shè)備包括的范圍（或擬使用）用戶可編程內(nèi)存.其中最簡單的通常是設(shè)備能夠通過使用一些輸入/輸出作為地址線額外的ROM選項和數(shù)據(jù)總線訪問外部內(nèi)存運行于微處理器模式。這種類型的設(shè)備可以表現(xiàn)為單芯片微型計算機(jī)盡管有限制的I/O和外部修改這些設(shè)備的電路。在永久性內(nèi)存的制造中小內(nèi)存裝置的應(yīng)用是非常普遍的，但仍然可以以節(jié)省大量成本I/O和其它傳統(tǒng)的基于微處理器電路芯片相比。更準(zhǔn)確的ROM設(shè)備更換，可

7、在與“形式變種背馱式”EPROM（可擦除可編程只讀存儲器）插座或存儲器中，而不是ROM器件。這些器件自然價格比同等ROM但不提供完整的等效電路得設(shè)備貴。EPROM的設(shè)備對于低容量應(yīng)用中也非常有吸引力，他們提供的單芯片器件的優(yōu)勢，在以下方面的板載I/O等，在靈活的用戶可編程帶來的便利。</p><p>　　隨機(jī)存取存儲器（RAM）。RAM用于變量和工作在程序使該存儲器的執(zhí)行隨數(shù)據(jù)存儲設(shè)備的大小不同類型而有所不同，但

8、作為處理器具有相同的特征寬度（4,8,16比特等）。特殊功能寄存器，如棧指針或定時器寄存器，往往邏輯納入內(nèi)存區(qū)域也在型微電腦的硬件中做集中內(nèi)存，它在內(nèi)存和處理器之間的區(qū)別在通常不物理上分開的微機(jī)中是不必要的區(qū)分。</p><p>　　中央處理單元（CPU）。CPU是很象微型電子計算機(jī)和微控制器的任何微電腦。許多微電腦和微控制器涉及到二進(jìn)制編碼(十進(jìn)制處理（BCD）的數(shù)據(jù)為例）數(shù)字顯示。因而，常?？梢园l(fā)現(xiàn)該CPU是

9、很適合處理這種類型的數(shù)據(jù)。對設(shè)施良好與否進(jìn)行的測試，設(shè)置和重置單個位的內(nèi)存或I/O控制器的應(yīng)用程序，也是常見的。因為許多涉及打開和關(guān)閉的單輸出線或在單線。這些線很容易連接到二進(jìn)制的設(shè)備，如開關(guān)，恒溫器，固態(tài)繼電器，閥門，電機(jī)等。</p><p>　　并行輸入/輸出。并行輸入和輸出的計劃有所不同，在不同的微機(jī)、在大多數(shù)設(shè)立一個機(jī)制，至少選擇讓其中一些引腳輸出。一些引腳輸入是非常靈活的。這可能適用于所有或端口。有些I

10、/O線直接連接到適當(dāng)?shù)脑O(shè)備，例如，熒光顯示器，也可以提供足夠的電流，使接口和其他設(shè)備直接相連。一些設(shè)備允許一個I/O端口,其他組件將作為系統(tǒng)總線配置為允許片外存儲器和I/O擴(kuò)展。這個設(shè)施是潛在有用的一個產(chǎn)品系列的發(fā)展，因為連續(xù)增強(qiáng)可能成為太上存儲器，這是不可取的，不是建立在現(xiàn)有的軟件基礎(chǔ)上的。</p><p>　　串行輸入/輸出。串行通信是指與終端設(shè)備的鏈接使用少量的通訊線。這種通訊也可利用特殊的接口連接功能芯片

11、使幾個微型機(jī)連在一起。雙方共同異步同步通信方案要求的規(guī)則提供成幀（啟動和停止）的信息。這可以作為一個硬件設(shè)施或U（擰）藝術(shù)（通用執(zhí)行（同步）異步接收器/發(fā)送器）減輕處理器（和應(yīng)用程序）的這種低層次的確費時，它也只需要選擇一個波特率及其他可能的選擇（停止位，奇偶校驗等）和負(fù)載號碼（或讀取），串行發(fā)送器（或接收）的緩沖器進(jìn)行適當(dāng)?shù)母袷降臄?shù)據(jù)串行處理，然后由硬件電路完成。</p><p>　　定時/計數(shù)器設(shè)施。許多應(yīng)用

12、的單片機(jī)需要對過去的真實時間準(zhǔn)確的評價。這可以由每個程序中的執(zhí)行時間分支認(rèn)真評估，但除最簡單的程序外，他的工作效率不高。首選方法是使用計時器電路，能獨立計算精確的時間增量，并生成一個預(yù)設(shè)的時間后中斷的時間。這種類型的定時器通常在所要求的數(shù)量可重載中應(yīng)用。計時器然后減少此值產(chǎn)生中斷或設(shè)置標(biāo)記時，計數(shù)器到達(dá)零。更好的計時器有自動加載初始值的功能。這將緩解重新加載計數(shù)器和評估所用的時間，計時器重新啟動之前這是必要的。有時候與定時器相關(guān)的是一個

13、事件計數(shù)器。這個設(shè)備通常有一個特殊的輸入引腳，可直接驅(qū)動計數(shù)器。</p><p>　　定時元件。大多數(shù)微型計算機(jī)時鐘電路只需要簡單的計時元件。如果要求最高性能，必須使用晶體以確保最大時鐘頻率接近，但不會超出。許多時鐘電路，還具有電阻和低電容工作成本定時元件，也可以從外部源驅(qū)動。這后一種安排是有用的在微機(jī)外部同步是必需的時候。 </p><p><b>　　B:PLC</b&

14、gt;</p><p>　　今天的PLC（可編程邏輯控制器）將面對日益復(fù)雜的挑戰(zhàn)。如果將他們比作細(xì)胞，偶爾向主機(jī)報告，賦予新的工作和新的語言，一旦他們悄悄地取代繼電器，將被迫和大量的控制產(chǎn)品競爭。對于今年的年度PLC技術(shù)的更新，我們對PLC的制造商會就這些主題提出更多問題.</p><p><b>　　編程語言</b></p><p>　　更高

15、水平的PLC編程語言已經(jīng)推行有一段時間了。但最近的流行，如雨后春筍般。正如雷蒙德萊韋耶，副總裁兼總經(jīng)理，西門子能源和自動化公司，可編程控制正在為更復(fù)雜的操作使用，梯形邏輯比語言變得更加實際、有效和強(qiáng)大的。舉例來說，很難寫三角函數(shù)使用梯形邏輯?！罢Z言為人們所接受，包括布爾，控制系統(tǒng)流程圖，這種功能圖及其變化圖表語言。而且有越來越多像C和BASIC語言的興趣?！?lt;/p><p><b>　　在過程的PLC控

16、制</b></p><p>　　到目前為止，PLC的沒有大量用于連續(xù)過程控制，會一直這樣么嗎？“我感覺到了，PLC將用于過程工業(yè)，但不一定過程控制?！盝annotta說。幾個供應(yīng)商，顯然是把賭注押在相反會發(fā)生，已經(jīng)實行了PLC的應(yīng)用優(yōu)化的過程。富瑞安的經(jīng)理認(rèn)為PLC將越來越多地使用食品等行業(yè)，化工，石化.Ryan認(rèn)為有兩種類型的應(yīng)用程序中，他們是合適的?！爸唬彼f，“是其中的過程控制系統(tǒng)，目前已被

17、沒有理由自動化DCS的大小[分布式控制系統(tǒng)]隨著價格標(biāo)簽開始。產(chǎn)品的選擇是比較高，可編程控制器為小，低環(huán)數(shù)的應(yīng)用意義。第二種是你必須融入順序邏輯。批次控制循環(huán)密切合作是最好的例子，那里的順序和維持過程變量是交織在一起的密切合作，使擁有一個可編程控制器的邏輯順序做的好處遠(yuǎn)遠(yuǎn)超過了不具有分布式控制系統(tǒng)的一些缺點?！?lt;/p><p>　　Bill Barkovitz，Triconex的總統(tǒng)，預(yù)言：“今后所有的控制器在過

18、程控制系統(tǒng)的業(yè)務(wù)將引用更多的PLC技術(shù)，PLC功能比以往任何時候都要多。”</p><p><b>　　通信和規(guī)范</b></p><p>　　在整體上通信是至關(guān)重要的個人自動化單元對自動化工廠來說。我們聽說了很多規(guī)范在過去數(shù)年，許多公司都紛紛跟進(jìn)。但是，不少人失望的發(fā)現(xiàn)，完成地圖規(guī)范并沒有立即出現(xiàn)。拉里科馬雷克說：“現(xiàn)在，規(guī)范仍然是一個移動目標(biāo)，規(guī)范沒有最終決定，對

19、于制造商。目前，正在推出的產(chǎn)品樣本.人們使其產(chǎn)品滿足MAP2.1標(biāo)準(zhǔn)。然而，新標(biāo)準(zhǔn)MAP3.0被引進(jìn)時，MAP2.1為基礎(chǔ)的產(chǎn)品將被淘汰時?！?lt;/p><p>　　正因為如此，許多PLC廠商正在制定完整的規(guī)范。 例如Omron，擁有一個完整的兼容程序，但弗蘭克紐伯恩，副歐姆龍工業(yè)部總裁，報告說，由于缺乏公司的定義，歐姆龍的PLC還談不上規(guī)范。 由于不太可能將個人的PLC廣泛的交談，制造商更專注于專有的網(wǎng)絡(luò).

20、按照薩爾Provanzano說法，用戶擔(dān)心，如果他們不從規(guī)則上和供應(yīng)商妥協(xié)，他們將要加大對通信結(jié)構(gòu)的不支持。</p><p><b>　　通用的I/O</b></p><p>　　然而大多數(shù)PLC的兼容問題不同廠商的溝通不夠，在另一端連接的I/O問題-更是支離破碎的。除了少數(shù)例外，I/O是仍然專有技術(shù)。然而，誰是那些感覺的I/O最終將成為更具有普遍性。GE Fanuc

21、的希望這樣做與天才智能I/O線.各個獨立I/O制造商都在同一方向進(jìn)發(fā)。</p><p>　　許多人說，I/O是這樣一個高價值項目，PLC制造商將永遠(yuǎn)希望保持它的專有性。由于肯Jannotta說：“ I/O將在硬件銷售中不成比例-當(dāng)然每個PLC供應(yīng)商將試圖保護(hù)這一點。”出于這個原因，他說，PLC的制造商將不會開始銷售通用I/O和其他廠商的系統(tǒng)?！叭绻覀冮_始銷售該產(chǎn)品的實物，那我們還有什么可生產(chǎn)的？”Jannott

22、a說道。</p><p>　　隨著更多智能I/O出現(xiàn)，薩爾Provanzano認(rèn)為在不同的制造商中間這將導(dǎo)致更多的分化。“哪里的I/O變得非常聰明，并成為系統(tǒng)的一部分真的很難定義，哪些是I/O，哪些是CPU.隨著分布式的發(fā)展，如果你愿意，CPU也同樣可以納入作為I/O的系統(tǒng)”</p><p>　　PLC的 I / O和個人電腦的連接</p><p>　　雖然不同的P

23、LC廠商可能會繼續(xù)用專有的I/O，但一些廠商使I/O連接到IBM PC這樣的兼容設(shè)備成為可能.Alle - bradeley和辛辛那提米拉克龍公司已經(jīng)擁有，并有傳言說-通用的電氣計劃將沿著同樣的思路?？颂貭柡兀珿E Fanuc北美的產(chǎn)品規(guī)劃經(jīng)理，認(rèn)為是I/O的普及“我想多個主機(jī)接口將代替I/O的趨勢，”他說。朱迪格洛爾，美商自動化產(chǎn)品的市場經(jīng)理，將PLC看做是工業(yè)電腦。</p><p><b>　　P

24、LC VS電腦</b></p><p>　　如果IBM 7552，行動儀器BC22，和其他計算機(jī)出現(xiàn)在工廠，這意味著不會對PLC的新的競爭？富瑞安：“有一些控制功能，可用于電腦?？删幊坛绦蚩刂破鞲玫墓ぷ饕驯黄冗m應(yīng)這些應(yīng)用。“然而，在我們調(diào)查的廠商多數(shù)不認(rèn)為“個人電腦入侵”將對他們產(chǎn)生問題。大多表示PLC和PC結(jié)構(gòu)上的差別決定他們不同的作用，PC將主管通訊和管理，PLC則進(jìn)行控制，他們相信這只是意味著

25、，PLC和個人電腦將能夠共享相同的數(shù)據(jù)。</p><p>　　富瑞恩說：“通用的計算機(jī)內(nèi)在結(jié)構(gòu)不同，可編程控制器硬件結(jié)構(gòu)有內(nèi)置到幾乎每一個制造商的可編程控制器。今天定制的硬件來運行梯形邏輯，解決機(jī)器代碼。”在根本的區(qū)別上，他引用了一個稱呼“機(jī)器狀態(tài)”。富瑞安說：“當(dāng)你關(guān)閉機(jī)器，或中斷周期，或者跳轉(zhuǎn)到另一個周期，現(xiàn)場可編程控制器本身記得機(jī)器的狀態(tài)：定時器狀態(tài)是什么，計數(shù)器狀態(tài)是什么，鎖存的狀態(tài)是什么,但計算機(jī)本身不

26、這樣做。”</p><p><b>　　外文原文</b></p><p>　　A: Fundamentals of Single-chip Microcomputer</p><p>　　The single-chip microcomputer is the culmination of both the development of the

27、 digital computer and the integrated circuit arguably the tow most significant inventions of the 20th century [1].</p><p>　　These tow types of architecture are found in single-chip microcomputer. Some employ

28、 the split program/data memory of the Harvard architecture, shown in Fig.3-5A-1, others follow the philosophy, widely adapted for general-purpose computers and microprocessors, of making no logical distinction between pr

29、ogram and data memory as in the Princeton architecture, shown in Fig.3-5A-2.</p><p>　　In general terms a single-chip microcomputer is characterized by the incorporation of all the units of a computer into a

30、single device, as shown in Fig3-5A-3.</p><p>　　Fig.3-5A-1 A Harvard type</p><p>　　Fig.3-5A-2. A conventional Princeton computer</p><p><b>　　Reset</b></p><p

31、>　　Interrupts</p><p><b>　　Power</b></p><p>　　Fig3-5A-3. Principal features of a microcomputer</p><p>　　Read only memory (ROM).</p><p>　　ROM is usually fo

32、r the permanent, non-volatile storage of an applications program .Many microcomputers and m are intended for high-volume applications and hence the economical manufacture of the devices requires that the contents of the

33、program memory be committed permanently during the manufacture of chips . Clearly, this implies a rigorous approach to ROM code development since changes cannot be made after manufacture .This development process may inv

34、olve emulation using a sophisticated develo</p><p>　　Some manufacturers provide additional ROM options by including in their range devices with (or intended for use with) user programmable memory. The simple

35、st of these is usually device which can operate in a microprocessor mode by using some of the input/output lines as an address and data bus for accessing external memory. This type of device can behave functionally as th

36、e single chip microcomputer from which it is derived albeit with restricted I/O and a modified external circuit. The use of th</p><p>　　Random access memory (RAM).</p><p>　　RAM is for the storag

37、e of working variables and data used during program execution. The size of this memory varies with device type but it has the same characteristic width (4,8,16 bits etc.) as the processor ,Special function registers, suc

38、h as stack pointer or timer register are often logically incorporated into the RAM area. It is also common in Harard type microcomputers to treat the RAM area as a collection of register; it is unnecessary to make distin

39、ction between RAM and processor registe</p><p>　　Central processing unit (CPU).</p><p>　　The CPU is much like that of any microprocessor. Many applications of microcomputers and microcontrollers

40、 involve the handling of binary-coded decimal (BCD) data (for numerical displays, for example) ,hence it is common to find that the CPU is well adapted to handling this type of data .It is also common to find good facili

41、ties for testing, setting and resetting individual bits of memory or I/O since many controller applications involve the turning on and off of single output lines or the readin</p><p>　　Parallel input/output.

42、</p><p>　　Parallel input and output schemes vary somewhat in different microcomputer; in most a mechanism is provided to at least allow some flexibility of choosing which pins are outputs and which are input

43、s. This may apply to all or some of the ports. Some I/O lines are suitable for direct interfacing to, for example, fluorescent displays, or can provide sufficient current to make interfacing other components straightforw

44、ard. Some devices allow an I/O port to be configured as a system bus to allow off-c</p><p>　　Serial input/output .</p><p>　　Serial communication with terminal devices is common means of providin

45、g a link using a small number of lines. This sort of communication can also be exploited for interfacing special function chips or linking several microcomputers together .Both the common asynchronous synchronous communi

46、cation schemes require protocols that provide framing (start and stop) information .This can be implemented as a hardware facility or U(S)ART(Universal(synchronous) asynchronous receiver/transmitter) relieving </p>

47、<p>　　Timing/counter facilities.</p><p>　　Many application of single-chip microcomputers require accurate evaluation of elapsed real time .This can be determined by careful assessment of the execution

48、 time of each branch in a program but this rapidly becomes inefficient for all but simplest programs .The preferred approach is to use timer circuit that can independently count precise time increments and generate an in

49、terrupt after a preset time has elapsed .This type of timer is usually arranged to be reloadable with the required count .</p><p>　　Timing components. </p><p>　　The clock circuitry of most micro

50、computers requires only simple timing components. If maximum performance is required,a crystal must be used to ensure the maximum clock frequency is approached but not exceeded. Many clock circuits also work with a resis

51、tor and capacitor as low-cost timing components or can be driven from an external source. This latter arrangement is useful is external synchronization of the microcomputer is required. </p><p><b>　　B

52、:PLC[</b></p><p>　　PLC (programmable logical controller) face ever more complex challenges these days . Where once they quietly replaced relays and gave an occasional report to a corporate mainframe, t

53、hey are now grouped into cells, given new job and new languages, and are forced to compete against a growing array of control products. For this year's annual PLC technology update ,we queried PLC makers on these top

54、ics and more .</p><p>　　Programming languages </p><p>　　Higher level PLC programming languages have been around for some time ,but lately their popularity has mushrooming. "As Raymond Levei

55、lle, vice president & general manager, Siemens Energy &Automation .inc; Programmable controls are being used for more and more sophisticated operations, languages other than ladder logic become more practical, ef

56、ficient, and powerful. For example, it's very difficult to write a trigonometric function using ladder logic ."Languages gaining acceptance include Boolean</p><p>　　PLC in process control</p>

57、<p>　　Thus far, PLC have not been used extensively for continuous process control .Will this continue? "The feeling that I've gotten," says Ken Jannotta, manger, product planning, series One and Serie

58、s Six product ,at GE Fanuc North America ,'is that PLC will be used in the process industry but not necessarily for process control."</p><p>　　Several vendors -obviously betting that the opposite wi

59、ll happen -have introduced PLC optimized for process application .Rich Ryan, manger, commercial marketing, Allen-bradley Programmable Controls Div., cites PLC increasing use such industries as food ,chemicals ,and petrol

60、eum. Ryan feels there are two types of applications in which they're appropriate. "one," he says," is where the size of the process control system that's being automated doesn't justify DCS[dis

61、tributed control system].With th</p><p>　　Bill Barkovitz, president of Triconex, predicts that "all future controllers that come out in the process control system business will embrace a lot of more PLC

62、 technology and a lot more PLC functionality than they ever did before ."</p><p>　　Communications and MAP</p><p>　　Communications are vital to an individual automation cell and to be automa

63、ted factory as a whole. We've heard a lot about MAP in the last few years ,and a lot of companies have jumped on the bandwagon.Many, however, were disappointed when a fully-defined and completed MAP specification di

64、dn't appear immediately .Says Larry Komarek: "Right now, MAP is still a moving target for the manufacturers, a specification that is not final .Presently, for example. people are introducing products to meet th&

65、lt;/p><p>　　Because of this, many PLC vendors are holding off on full MAP implementations. Omron, for example, has an ongoing MAP-compatibility program;but Frank Newburn, vice president of Omron's Industria

66、l Division ,reports that because of the lack of a firm definition ,Omron's PLC don't yet talk to MAP.</p><p>　　Since it's unlikely that an individual PLC would talk to broad MAP anyway, makers ar

67、e concentrating on proprietary networks. According to Sal Provanzano, users fear that if they do get on board and vendors withdraw from MAP, they'll be the ones left holding a communications structure that's not

68、supported.</p><p>　　Universal I/O</p><p>　　While there are concerns about the lack of compatible communications between PLC from different vendors, the connection at the other end-the I/O-is eve

69、n more fragmented .With rare exceptions, I/O is still proprietary .Yet there are those who feel that I/O will eventually become more universal .GE Fanuc is hoping to do that with its Genius smart I/O line. The independen

70、t I/O makers are pulling in the same direction. </p><p>　　Many say that I/O is such a high-value item that PLC makers will always want to keep it proprietary .As Ken Jannotta, says: "The I/O is going to

71、 be a disproportionate amount of the hardware sale. Certainly each PLC vendor is going to try to protect that. "For that reason, he says, PLC makers won't begin selling universal I/O system from other vendor. &q

72、uot;if we start selling that kind of product, "says jannotta, "what do we manufacture?"</p><p>　　With more intelligent I/O appearing, Sal Provanzano feels this will lead to more differentiatio

73、n among I/O from different makers. "Where the I/O becomes extremely intelligent and becomes part of the system, "he says, "it really is hard to define which is the I/O and which is CPU. It really CPU, if y

74、ou will, is equally integrated into the system as the I/O."</p><p>　　Connecting PLC I/O to PC</p><p>　　While different PLC probably will continue to use proprietary I/O, several vendors mak

75、e it possible to connect5 their I/O to IBM PC-compatible equipment. Alle-bradeley, Could, and Cincinnati Milacron already have, and rumor has it that GE is planning something along these same lines .Bill Ketelhut, mana

76、ge of product planning at GE Fanuc North America ,sees this sort of thing as alternative to universal I/O."I think the trend ,instead of toward universal I/O, will be multiple host interface ," </p><

77、p><b>　　PLC VS PC</b></p><p>　　If the IBM 7552, the Action Instruments BC22,and other computers are appearing on the factory floor, won't this mean new competition for PLC? Rich Ryan: "

78、;There are some control functions that are better jobs for computers. Programmable controllers have been forced to fit into those applications. "Yet, the majority of vendors we surveyed don't like the "PC i

79、nvasion" will pose a problem for them .Most said that PLC and PCs are enough apart in architecture that they will usually do the control. The</p><p>　　"There are inherent architectural differences

80、between a general purpose computer," says Rich Ryan, "and a programmable controller .There are hardware constructs built into almost every manufacture's programmable controller today that customize the hard

81、ware to run ladder logic and to solve machine code. "One fundamental difference he cites is called state of the machine .Ryan: "When you shut the machine off, or interrupt the cycle, or you jump to another spot

82、 in the cycle, programmable controller</p><p>　　[1]V. Yu. Teplov,A. V. Anisimov. Thermostatting System Using a Single-Chip Microcomputer and Thermoelectric Modules Based on the Peltier Effect[J] ,2002</p