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英文文献翻译学 生 姓名刘学毅专 业自动化学 号0833141分 院电子工程分院2012年 6 月1. 外文原文A: Fundamentals of Single-chip Microcomputer The single-chip microcomputer is the culmination of both the development of the digital computer and the integrated circuit arguably the tow most significant inventions of the 20th century These tow types of architecture are found in single-chip microcomputer. Some employ the split program/data memory of the Harvard architecture, others follow the philosophy, widely adapted for general-purpose computers and microprocessors, of making no logical distinction between program and data memory as in the Princeton architecture, shown in Fig.3-5A-2.In general terms a single-chip microcomputer is characterized by the incorporation of all the units of a computer into a single device.Read only memory (ROM) ROM is usually for the permanent, non-volatile storage of an applications program .Many microcomputers 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 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 involve emulation using a sophisticated development system with a hardware emulation 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 programmable 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 external memory. This type of device can behave functionally as the single chip microcomputer from which it is derived albeit with restricted I/O and a modified external circuit. The use of these ROM less devices is common 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 compared to a conventional microprocessor based circuit. More exact 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 expensive than equivalent ROM device, but do provide complete circuit equivalents. EPROM based devices are also extremely 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 flexible user programmability.Random access memory (RAM). RAM is for the storage 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, such as stack pointer or timer register are often logically incorporated into the RAM area. It is also common in Hard type microcomputers 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 microcomputer .Central processing unit (CPU). The CPU is much like that of any microprocessor. Many applications of microcomputers and microcontrollers 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 facilities 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, valves, motor, etc.Parallel input/output. 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 inputs. 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 straightforward. Some devices allow an I/O port to be configured as a system bus to allow off-chip memory and I/O expansion. This facility is potentially useful as a product range develops, since successive enhancements may become too big for on-chip memory and it is undesirable not to build on the existing software base.Serial input/output . Serial communication with terminal devices is common means of providing 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 communication 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 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. Serialization of the data in the appropriate format is then handled by the hardware circuit.Timing/counter facilities. Many application of single-chip microcomputers require accurate evaluation of elapsed real time .This can be determined by careful assessment of the execution 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 interrupt after a preset time has elapsed .This type of timer is usually arranged to be reloadable with the required count .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 before the timer restarted ,which otherwise wound be necessary if continuous precisely timed interrupts were required (as in a clock ,for example).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 components. The clock circuitry of most microcomputers 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 resistor 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. 2. 外文资料翻译译文单片机基础单片机是电脑和集成电路发展的巅峰,有据可查的是他们也是20世纪最有意义的两大发明。这两种特性在单片机中得到了充分的体现。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,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。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,经济的设备制造要求的程序存储器的内容是在制造期间永久性的刻录在芯片中,这意味着严谨的方法,因为修改ROM代码不能制造之后发展。这一发展过程可能涉及仿真,使用硬件仿真功能以及强大的软件工具使用先进的开发系统。一些制造商在其提供的设备包括的范围(或拟使用)用户可编程内存.其中最简单的通常是设备能够运行于微处理器模式通过使用一些输入/输出作为地址线额外的ROM选项和数据总线访问外部内存.这种类型的设备可以表现为单芯片微型计算机尽管有限制的I / O和外部修改这些设备的电路.小内存装置的应用是非常普遍的在永久性内存的制造中 2;但仍然可以在我节省大量成本I/ O和其它芯片相比,传统的基于微处理器电路.更准确的ROM设备更换,可在与形式变种背驮式EPROM(可擦除可编程只读存储器)插座或存储器,而不是ROM器件。这些器件自然价格比同等ROM设备贵,但不提供完整的等效电路.EPROM的设备也非常有吸引力对于低容量应用中,他们提供的单芯片器件的优势,在以下方面的板载I / O等,在灵活的用户可编程带来的便利。随机存取存储器(RAM)RAM用于变量和工作在程序使用该存储器的执行.随数据存储设备的大小不同类型而有所不同,但具有相同的特征宽度(4,8,16 比特等)作为处理器。特殊功能寄存器,如栈指针或定时器寄存器,往往逻辑纳入内存区域.它也在型微电脑的硬件中做集中内存,它是不必要的区分内存和处理器之间的区别在通常不物理上分开的微机中。中央处理单元(CPU)CPU是很象微型电子计算机和微控制器的任何微电脑.许多微电脑和微控制器涉及到二进制编码(十进制处理(BCD)的数据为例)数字显示,因而,常常可以发现该CPU是很适合处理这种类型的数据。对设施良好与否进行的测试,设置和重置单个位的内存或I / O控制器的应用程序,也是常

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