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1、-1、外文原文复印件 A:Fundamentals of Single-chip Microputer The single-chip microputer is the culmination of both the development of the digital puter and the integrated circuit arguably the tow most significant inventions of the 20th century 1.These tow types of architecture are found in single-chip microp

2、uter.Some employ the split program/data memory of the Harvard architecture,shown in Fig.3-5A-1,others follow the philosophy,widely adapted for general-purpose puters and microprocessors,of making no logical distinction between program and data memory as in the Princeton architecture,shown in Fig.3-5

3、A-2.In general terms a single-chip microputer is characterized by the incorporation of all the units of a puter into a single device,as shown in Fig3-5A-3.Fig.3-5A-1 A Harvard type Fig.3-5A-2.A conventional Princeton puter Reset Interrupts Power Fig3-5A-3.Principal features of a microputer Read only

4、 memory(ROM).ROM is usually for the permanent,non-volatile storage of an applications program.Many microputers and microcontrollers are intended for high-volume applications and hence the economical manufacture of the devices requires that the contents of the program memory be mitted permanently dur

5、ing 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 involve emulation using a sophisticated development system with a hardware emulation Program memory Data memory CPU Input&Output u

6、nit memory CPU Input&Output unit E*ternal Timing ponents System clock Timer/Counter Serial I/O Prarallel I/O RAM ROM CPU-capability as well as the use of powerful software tools.Some manufacturers provide additional ROM options by including in their range devices with(or intended for use with)user p

7、rogrammable memory.The simplest 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 e*ternal memory.This type of device can behave functionally as the single chip microputer from which it is derived al

8、beit with restricted I/O and a modified e*ternal circuit.The use of these ROMless devices is mon even in production circuits where the volume does not justify the development costs of custom on-chip ROM2;there can still be a significant saving in I/O and other chips pared to a conventional microproc

9、essor based circuit.More e*act replacement for ROM devices can be obtained in the form of variants with piggy-back EPROM(Erasable programmable ROM)sockets or devices with EPROM instead of ROM。These devices are naturally more e*pensive than equivalent ROM device,but do provide plete circuit equivalen

10、ts.EPROM based devices are also e*tremely attractive for low-volume applications where they provide the advantages of a single-chip device,in terms of on-chip I/O,etc.,with the convenience of fle*ible user programmability.Random access memory(RAM).RAM is for the storage of working variables and data

11、 used during program e*ecution.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,such as stack pointer or timer register are often logically incorporated into the RAM area.It is also mon in Harard typ

12、e microputers to treat the RAM area as a collection of register;it is unnecessary to make distinction between RAM and processor register as is done in the case of a microprocessor system since RAM and registers are not usually physically separated in a microputer.Central processing unit(CPU).The CPU

13、 is much like that of any microprocessor.Many applications of microputers and microcontrollers involve the handling of binary-coded decimal(BCD)data(for numerical displays,for e*ample),hence it is mon to find that the CPU is well adapted to handling this type of data.It is also mon to find good faci

14、lities 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 reading the single line.These lines are readily interfaced to two-state devices such as switches,thermostats,solid-state relays,va

15、lves,motor,etc.Parallel input/output.Parallel input and output schemes vary-somewhat in different microputer;in most a mechanism is provided to at least allow some fle*ibility of choosing which pins are outputs and which are inputs.This may apply to all or some of the ports.Some I/O lines are suitab

16、le for direct interfacing to,for e*ample,fluorescent displays,or can provide sufficient current to make interfacing other ponents straightforward.Some devices allow an I/O port to be configured as a system bus to allow off-chip memory and I/O e*pansion.This facility is potentially useful as a produc

17、t range develops,since successive enhancements may bee too big for on-chip memory and it is undesirable not to build on the e*isting software base.Serial input/output.Serial munication with terminal devices is mon means of providing a link using a small number of lines.This sort of munication can al

18、so be e*ploited for interfacing special function chips or linking several microputers together.Both the mon asynchronous synchronous munication schemes require protocols that provide framing(start and stop)information.This can be implemented as a hardware facility or U(S)ART(Universal(synchronous)as

19、ynchronous receiver/transmitter)relieving the processor(and the applications programmer)of this low-level,time-consuming,detail.t is merely necessary to selected a baud-rate and possibly other options(number of stop bits,parity,etc.)and load(or read from)the serial transmitter(or receiver)buffer.Ser

20、ialization of the data in the appropriate format is then handled by the hardware circuit.Timing/counter facilities.Many application of single-chip microputers require accurate evaluation of elapsed real time.This can be determined by careful assessment of the e*ecution time of each branch in a progr

21、am but this rapidly bees inefficient for all but simplest programs.The preferred approach is to use timer circuit that can independently count precise time increments and generate an interrupt after a preset time has elapsed.This type of timer is usually arranged to be reloadable with the required c

22、ount.The timer then decrements this value producing an interrupt or setting a flag when the counter reaches zero.Better timers then have the ability to automatically reload the initial count value.This relieves the programmer of the responsibility of reloading the counter and assessing elapsed time

23、before the timer restarted,which otherwise wound be necessary if continuous precisely timed interrupts were required(as in a clock,for e*ample).Sometimes associated with timer is an event counter.With this facility there is usually a special input pin,that can drive the counter directly.Timing ponen

24、ts.The clock circuitry of most microputers-requires only simple timing ponents.If ma*imum performance is required,a crystal must be used to ensure the ma*imum clock frequency is approached but not e*ceeded.Many clock circuits also work with a resistor and capacitor as low-cost timing ponents or can

25、be driven from an e*ternal source.This latter arrangement is useful is e*ternal synchronization of the microputer is required.WORDS AND TERMS culmination n.顶点 spilt adj.别离的 volatile n.易变的 mit v.保证 albeit conj.虽然 custom adj.定制的 variant adj.不同的 piggy-back adj.背负式的 socket n.插座 B:PLC1 PLCs(programmable

26、logical controller)face ever more ple*challenges these days.Where once they quietly replaced relays and gave an occasional report to a corporate mainframe,they are now grouped into cells,given new job and new languages,and are forced to pete against a growing array of control products.For this years

27、 annual PLC technology update,we queried PLC makers on these topics and more.Programming languages Higher level PLC programming languages have been around for some time,but lately their popularity has mushrooming.As Raymond Leveille,vice president&general manager,Siemens Energy&Automation.inc;Progra

28、mmable controls are being used for more and more sophisticated operations,languages other than ladder logic bee more practical,efficient,and powerful.For e*ample,its very difficult to write a trigonometric function using ladder logic.Languages gaining acceptance include Boolean,control system flowch

29、arting,and such function chart languages as Graphcet and its variation.And theres increasing interest in languages like C and BASIC.PLCs in process control Thus far,PLCs have not been used e*tensively for continuous process control.Will this continue The feeling that Ive gotten,says Ken Jannotta,man

30、ger,product planning,series One and Series Si*product,at GE Fanuc North America,is that PLCs will be used in the process industry but not necessarily for process-control.Several vendors-obviously betting that the opposite will happen-have introduced PLCs optimized for process application.Rich Ryan,m

31、anger,mercial marketing,Allen-bradley Programmable Controls Div.,cites PLCss increasing use such industries as food,chemicals,and petroleum.Ryan feels there are two types of applications in which theyre appropriate.one,he says,is where the size of the process control system thats being automated doe

32、snt justify DCSdistributed control system.With the starting price tags of chose products being relatively high,a programmable controller makes sense for small,low loop count application.The second is where you have to integrate the loop closely with the sequential logical.Batch controllers are prime

33、 e*ample,where the sequence and maintaining the process variable are intertwined so closely that the benefits of having a programmable controller to do the sequential logical outweighs some of the disadvantages of not having a distributed control system.Bill Barkovitz,president of Tricone*,predicts

34、that all future controllers that e out in the process control system business will embrace a lot of more PLC technology and a lot more PLC functionality than they ever did before.munications and MAP munications are vital to an individual automation cell and to be automated factory as a whole.Weve he

35、ard a lot about MAP in the last few years,and a lot of panies have jumped on the bandwagon.2Many,however,were disappointed when a fully-defined and pleted MAP specification didnt appear immediately.Says Larry Komarek:Right now,MAP is still a moving target for the manufacturers,a specification that i

36、s not final.Presently,for e*ample.people are introducing products to meet the MAP2.1standard.Yet2.1-based products will be obsolete when the new standard for MAP3.0 is introduced.Because of this,many PLC vendors are holding off on full MAP implementations.Omron,for e*ample,has an ongoing MAP-patibil

37、ity program;3but Frank Newburn,vice president of Omrons Industrial Division,reports that because of the lack of a firm definition,Omrons PLCs dont yet talk to MAP.Since its unlikely that an individual PLC would talk to broad MAP anyway,makers are concentrating on proprietary networks.According to Sa

38、l Provanzano,users fear that if they do get on board and vendors withdraw from MAP,theyll be the ones left holding a munications structure thats not supported.Universal I/O While there are concerns about the lack of patible munications-between PLCs from different vendors,the connection at the other

39、end-the I/O-is even more fragmented.With rare e*ceptions,I/O is still proprietary.Yet there are those who feel that I/O will eventually bee more universal.GE Fanuc is hoping to do that with its Genius smart I/O line.The independent I/O makers are pulling in the same direction.Many say that I/O is su

40、ch a high-value item that PLC makers will always want to keep it proprietary.As Ken Jannotta,says:The I/O is going to 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 wont begin selling universal I/O system

41、 from other vendor.if we start selling that kind of product,says jannotta,what do we manufacture With more intelligent I/O appearing,Sal Provanzano feels this will lead to more differentiation among I/O from different makers.Where the I/O bees e*tremely intelligent and bees part of the system,he say

42、s,it really is hard to define which is the I/O and which is CPU.It really CPU,if you will,is equally integrated into the system as the I/O.Connecting PLC I/O to PCs While different PLCs probably will continue to use proprietary I/O,several vendors make it possible to connect5 their I/O to IBM PC-pat

43、ible equipment.Alle-bradeley,Could,and Cincinnati Milacron already have,and rumor has it that GE is planning something along these same lines.4Bill Ketelhut,manage 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 towar

44、d universal I/O,will be multiple host interface,he says.Jodie Glore,director of marking,Square D Automation Products,Views it as another indication that PLCs are,and have been for some time,industrial puters.PLCs VS PCs If the IBM 7552,the Action Instruments BC22,and other puters are appearing on th

45、e factory floor,wont this mean new petition for PLCs Rich Ryan:There are some control functions that are better jobs for puters.Programmable controllers have been forced to fit into those applications.Yet,the majority of vendors we surveyed dont like the PC invasion will pose a problem for them.Most

46、 said that PLCs and PCs are enough apart in architecture that they will usually do the control.They dont feel that PCs will take jobs from PLCs just because PLC I/O modules can now be connected to PCs;they believe this simply means that PLCs and PCs will be able to share the same data.There are inhe

47、rent architectural differences between a-general purpose puter,says Rich Ryan,and a programmable controller.There are hardware constructs built into almost every manufactures programmable controller today that customize the hardware to run ladder logic and to solve machine code.One fundamental diffe

48、rence 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 in the cycle,programmable controllers inherently remember the state of the machine:what the timers were,what the counters were,what the states of all the latches were.p

49、uters dont inherently do that.WORDS AND TERMS bet v.确信 optimized n.优化程序 corporate adj.共同的 mushroom v.迅速开展 trigonometric function 三角函数 vendor n.厂商 tag n.标签 smart adj.智能型的 patible adj.兼容的 2、外文资料翻译译文 单片机根底 单 片 机 是 电 脑 和 集 成 电 路 开 展 的 巅 峰，有 据 可 查 的 是 他 们 也 是 20 世纪 最 有 意 义 的 两 大 创 造。这 两 种 特 性 在 单 片 机 中 得

50、 到 了 充 分 的 表 达。一 些 厂 家 用 这 两 种特 性 区 分 程 序 内 存 和 数 据 内 存 在 硬 件 中 的 特 性，如 图 3-5A-1，依 据 同 样的 原 理 广 泛 的 适 用 于 一 般 目 的 的 电 脑 和 微 电 脑，一 些 厂 家 在 程 序 内 存 和 数据 内 存 之 间 不 区 分 的 像 Princeton 特 性，展 示 如 图 3-5A-2.只 读 存 贮 器(ROM).ROM 是 通 常 的 永 久 性 的，非 应 用 程 序 的 易 失 性 存储 器。不 少 微 机 和 单 片 机 用 于 大 批 量 应 用，因 此，经 济 的 设 备