英文翻译英文翻译资料Systems Using MicroprocessorsElectronic systems are used for handling information in the most general sense/ this information may be telephone conversation/ instrument reading or a companys accounts/ but in each case the same main types of operation are involved/ the processing/ storage and transmission of information/ In conventional electronic design these operations are combined at the function level/ for example a counter/ whether electronic or mechanical/ stores the current count and increments it by one as required/ A system such as an electronic clock which employs counters has its storage and processing capabilities spread throughout the system because each counter is able to store and Process numbers/Present day microprocessor based systems depart from this conventional approach by separating the three functions of processing / storage / and transmission into different section of the system /This partitioning into three main functions was devised by Von Neumann during the 1940s/ and was not conceived especially for microcomputers/ Almost every computer ever made has been designed with this structure/ and despite the enormous range in their Physical forms/ they have all been of essentially the same basic design/In a microprocerror based system the Processing will be performed in the microprocessor so itself/ The storage will be by means of memory circuits and the communication of information into and out of the system will be by means of special input/output (I/O) circuits/ It would be impossible to identify a particular piece of hardware which performed the counting in a microprocessor based clock because the time would be stored in the memory and incremented at regular intervals by the microprocessor/ However / the software which defined the systems behavior would contain sections that performed as countersThe apparently rather abstract approach to the architecture of the microprocessor and its associated circuits allows it to be very flexible in use，since the system is defined almost entirely in softwareThe design process is largely one of software engineering/ and the similar problems of construction and maintenance which occur in conventional engineering are encountered when producing software/Figure 15/ 1illustrates how these three sessions within a microcomputer are connected in terms of the communication of information within the machineThe system is controlled by the microprocessor which supervises the transfer of information between itself and the memory and input/output sections/ The external connections relate to the rest(that is，the non-computer part)of the engineering system /Memory(RAM/ROM)Micro-ProcessorInput/Output Fig/15/1 Three Sections of a Typical MicrocomputerAlthough only one storage section has been shown in the diagram，in practice two distinct types of memory RAM and ROM are usedIn each case，the word memory is rather inappropriate since a computer memory is more like a filing cabinet in concept / Information is stored in a set of numbered boxes banditos referenced by the serial number of the box in question/Microcomputers use RAM(Random Access Memory into which data can be written and from which data can be read again when neededThis data can be read back from the memory in any sequence desired/ and not necessarily the same order which it was written/ hence the expression random access memory/ Another type of ROM (Read Only Memory) is used to hold fixed patterns of information which cannot be affected by the microprocessor/ these patterns are not lost when power is removed and are normally used to hold the Program which defines the behavior of a microprocessor based system/ ROMs can be read like RAMs/ but unlike RAMs they cannot be used to store variable information/ Some ROMs have their data patterns put in during manufacture/ while others are programmable by the user by means of special equipment and are called Programmable ROMs/ The widely used programmable ROMs are erasable by means of special ultraviolet Lamps and are referred to as EPROMs，short for Erasable Programmable Read Only Memories / Other new types of device can be erased electrically without the need for ultraviolet 1ight/ which are called Electrically Erasable Programmable Read Only Memories/ ERPROMs/The microprocessor processes data under the control of the program/ controlling the How of information to and from memory and input/output devices/ Some input/output devices are general-purpose types while others are designed for conktrol1ing special hardware such as disc drives or controlling information transmission to other computers /Most types of I/0 devices are Programmable to some extent/ allowing different modes of operation/ while some actually contain special-purpose micro process to permit quite complex operation to be carried out without directly involving the main microprocessor/The micro process or/ memory and input/output circuit may all be contained on the same integrated circuit provided that the application does not require too much program of data storage/ This is usually the case in low-cost application such as the controllers used in microwave ovens and automatic washing machines /The use of single package allows considerable severable cost savings to be made when articles are manufactured in large quantities As technology develops/ more and more powerful processors and larger and larger amounts of memory are being incorporated into single chip microcomputers with resulting saving in assembly costs in the final products/ For the foreseeable future/ however/ it will continue to be necessary to interconnect a number of integrated circuits to make a microcomputer whenever larger amounts of storage or input/output are required/Another major engineering application of microcomputers is in process control /Here the presence of the microcomputer is usually more apparent to the user because provision is normally made for programming the microcomputer for the particular application/ In process control applications the benefits of fitting the entire system on to a single chip are usually outweighed by the high design cost involved/ because this sort of equipment is produced in smaller quantities /Moreover/ process controllers are usually more complicated so that it is more difficult to make them as single integrated circuits/ Two approaches are possible /the controller can be implemented as a general-purpose microcomputer rather like a more robust version of a hobby computer / or as a packaged system / designed for replacing controllers base on older technologies such as electromagnetic relays/ in the former case the system would probably be programmed in conventional programming language such as the ones to be introduce later/ while in the other case a special-purpose language might be used /for example one which allowed the function of the controller to be described in terms of relay interconnections / In either case programs can be stored in RAM/ which allows them to be altered to suit changes in application/ but this makes the overall system vulnerable to 1oss of power unless batteries are used to ensure continuity of supply /A1ternativcly programs can be stored in ROM/ in which case they virtually become part of the electronic hardware and are often referred to as firmware/More sophisticated process controllers require minicomputers for their implementationalthough the use of large scale integrated circuits blurs the distinction between mini and microcomputers /Products and process controller of various kinds represent the majority of preset-day microcomputer applicators / the exact figures depending on ones interpretation of the word product / Virtually a11 engineering and scientific uses of micro-computers can be assigned to one or other of these categories/General Electronics Circuits1Power-supply CircuitsMost electronic equipment requires DC voltages for its operation/ There can be provided by batteries or internal power supplies that convert alternating current as available at the home electronic outlet into regulated DC voltages/ The first element in an internal DC power supply is a transformer/ which steps up or steps down the input voltage to a level suitable for the operation of the equipment /A secondary function of the transformer is to provide electronic ground insulation of the device from the power line to reduce potential hazards/ A rectifier/ normally a diode/ then follows the transformer/ In the past/ vacuum diodes and a wide variety of different materials such as germanium crystals or cadmium sulfide were employed in the low-power rectifiers used in electric equipment/ Today silicon rectifiers are used almost exclusively because of their low cost and high reliability/Fluctuations and tipples superimposed on the rectified DC voltage (noticeable as a hum in a malfunctioning audio amplifier) can be filtered out by a capacitor/ the larger the capacitor/ and the smaller the amount of ripple in the voltage/ More precise control over voltages levels and ripples can be achieved by a voltage regulator，which also makes the internal voltages independent of fluctuations that may be encountered at an outlet/ A simple often used voltages regulator is the sneer diode/ It consists of a solid-state p-n-junction diode/ which acts as an insulator up to a predetermined voltage/ above that voltage it becomes a conductor that bypasses excess voltages/More sophisticated voltage regulators are usually constructed as integrated circuits/2Amplifier Circuits Electronic amplifiers are used mainly to increase the voltage/ current/ or power of signal/ A linear amplifier provides signal amplification with little or no distortion/ so that the output is proportional to the input/ A nonlinear amplifier may produce a considerable change in the waveform of the signal/ Linear amplifier are used for audio and video signals/ whereas nonlinear amplifiers find use in oscillators/ power electronics/ modulators/ mixers/ logic circuits/ and other applications where an amplitude cutoff is desired/ Although vacuum tubes played a major role in amplifier in the past/ today either discrete transistor circuit or integrated circuits are mostly used/(1) Audio Amplifier Audio amplifiers/ such as are found in radios/ televisions sets/ citizens band (CB) radios/ and cassette recorders/ are generally operated at frequencies below 20 kilohertz (1kHz=1000cycle/sec)/ They amplify the electrical signal/ which then is converted to sound in a loudspeaker/ Operational amplifier (op-amps)/ build with integrated circuits and consisting of DC-coupled/ multistage/ linear amplifier/ are popular for audio amplifiers/(2) Video AmplifiersVideo amplifiers are used mainly for signals with a frequency spectrum range up to 6 megahertz (1 MHz=1 million cycles/sec)/ The signal handled by the amplifier becomes the visual information presented on the television screen/ with the signal amplitude regulating the brightness of the spot forming the images on the screen/ To achieve its function/ a video amplifier must operate over a wide band and amplify all frequencies equally and low distortion/(3) Radio Frequency AmplifierThese amplifiers boost the signal level of radio or television communication systems/ Their frequencies generally range from 100 kHz to 1GHz (1billion cycle/sec=1gigahertz) and can extend well into the microwave frequency range/3OscillatorsOscillators generally consist of an amplifier and some type of feedback/ The output signal is feed back to the input of the amplifier/ The frequency determining element may be a tuned inductance-capacitance circuit or a vibrating crystal/ Crystal-controlled oscillators offer the highest precision and stability/ Oscillators are used to produce audio and radio signal for a wide of variety of purpose/ For example/ simple audio-frequency oscillators are used in modem push-button telephones to transmit data to central telephone station for dialing/ Audio tones generated by oscillators are also found in alarm clock/ radios/ electronic organs/ computers/ and warning systems/ High-frequency oscillators are used in communications equipment to provide turning and signal detection functions/ Radio and television station use precise high frequency oscillators to produce transmitting frequency/4Magnetic sensorThe simplest magnetic sensor adopted in the embedded equipment is Halls effect sensor/ Hall Effect to find on one year by Edwin Hall Dr/ In case of existing in magnetic field / flow semiconductor device is it can produce voltage to put in magnetic field year/ this voltage and electric current are in direct proportion to intensity of magnetic induction/Hall makes effect sensor on the silicon chip/ the voltage produced has several microvolt / gauss only/ So/ should adopt high and gain the amplifier to enlarge the signal outputted from Halls components and parts to the available range/ Hall effect sensor integrate of the same encapsulation with the sensor Entrance amplifier already/While requiring the output of the sensor is in direct proportion to magnetic field/ or the switch should change the state when exceeding a certain level in magnetic field/ at this moment/ can adopt Halls effect sensor/ Suitable for not needing not knowing simulation Hall effect sensor magnet from how much sensor costs from occasion/ for example/ are detecting and shaking the arm and really moving/ Halls effect sensor is most suitable for surveying the application whether the magnet approached the sensor/ for example/ detect the safety guard to open or close/The output end of the simulation Halls effect sensor can be reached the comparator or exported ADC that the sensor is similar to with any other voltage by the interface/ One point must be should pay attention toed/ simulation outputs the sensor and offers and supplies the proportional output amount of the voltage/ For get having noise export/ must adopt one with noise/ and regulate good power into sensor supply power accurate/ In a situation that there is no magnetic field to exist/ the output of the typical simulation Halls effect sensor / in order to supply the middle value of the voltage between the voltage and ground wire/ When the north magnetic pole is here near the sensor/ the voltage is to sports towards the place/ and when the south magnetic pole nears the sensor/ the voltage moves in the direction of the straight power/ Hall Effect switch produce figure is it is it indicates the existence of the magnetic field to come out to fail/ When the magnetic force (sports are clicked) is detected to/ Hall drives and exports effect sensor/ after the magnetic field drops to certain level (releasing value)/ Hall forbids exporting effect sensor/ In releasing some ranges lower than the operating point/ certain stagnate range of magnetism exists/Halls effect switch can be divided into two kinds -And the multicolor type is turned on or off very much only/ calls and has no locking and locking type switch sometimes/ The bipolar switch has operating points of a positive pole (south magnetic pole) and a negative pole (north magnetic pole) to release and click/ The switch has operating points of a positive pole (south magnetic pole) and an each positive pole to release and click very much only/ In two kinds of situations/ real some work and release are up to temperature differently and differently/ And the bipolar switch will usually have an associative making the output end of collectors with external resistor very much only/Hall Effect sensor coherent to adopt similar to transistor outer cover of TO-92 3 wire encapsulation/ separately for power in 3 stick wires in these/ and cant export/ Though the voltage of operation of some sensors reaches 30V or higher/ the voltage of supply of this kind of sensor is usually 5-10V/ When use Halls effect sensor/ should remember to solve the magnetic field and deviate from the problem/ If adopt magnet/ such as the rotation axis/ should guarantee the excessive magnetization rotation axis of the magnet/ otherwise will influence the output of the sensor/The magnetic field is that counted decaying with the square of distance to make sure to keep in mind/ Affected by intensity of magnetic field/ the output of the simulation Halls effect sensor may become the line sexual relations with the intensity of the magnetic field/ but will not be with the sexual relations before becoming the line/5Switching and Timing CircuitsSwitching and Timing circuits/ or logic circuits/ form the heart of any device where signals must be selected or combined in a controlled manner/ Applications of these circuits include telephone switching/ satellite transmissions/ and digital computer operations/Digital logic is a rational process for making simple “true” or “false” decisions based on the rules of Boolean algebra/ “True” can be presented by a “1” and “false” by a “0”/ and in logic circuits the numerals appear as signal of two different voltages/ Logic circuits are used to make special true-false decisions based on the presence of multiple true false signals at the inputs/ The signal may be generated by mechanical switches or by solid-state transducers/ Once the input signal has been accepted and conditioned (to remove unwanted electrical signal/ or “noise”)/ it is processed by the digital logic circuits/ The various families of digital logic devices/ usually integrated circuits/ perform a variety of logic functions through logic gates/ including “OR”/ “AND”/ and “NOT”/ and combinations of these (such as “NOR”/ which includes both OR and NOT)/ One widely used logic family is the transistor-transistor logic (TTL)/ Another family is the complementary metal oxide semiconductor logic (CMOS)/ which performs similar functions at very low power levels but at slightly lower op
免责声明：
1. 《外文翻译--工程中的微型计算机》内容来源于互联网，版权归原著者或相关公司所有。
2. 若《86561825文库网》收录的文本内容侵犯了您的权益或隐私，请立即通知我们删除。
