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Computer Hardware,Chapter 2,(计算机硬件),转载请注明 ,Section A CPU,We build computer to solve problems. Early computer solved mathematical and engineering problems, and later computers emphasized information processing for business applications. Today, the computer also control machines as diverse as automobile, engines, robots, and microwave ovens. A computer system solves a problem from any of these domains by accepting input, processing it, and producing output. Computer systems consist of hardware and software. Hardware is the physical part of the system. Once designed, hardware is difficult and expensive to change. Software is the set of programs that instruct the hardware and is easier to modify than hardware. Computers are valuable because they are general-purpose machines that can solve many different kinds of problems, as opposed to special-purpose machines that can each solve only one kind of problem. Different problems can be solved with the same hardware by supplying the system with a different set of instructions. That is, with different software.,microwave,maikruweiv n. 1. 微波 2. 微波炉 vt. 1. 用微波炉热(食物);用微波炉烹调 domain domen n. 1、领土, 领地, (活动、学问等的)范围, 领域 2、领土权 3、(政府或私人的) 所有地, 地产 4、地区, 区域 hardware hrd,wr n. 1、(计算机的)硬件, (电子仪器的)部件,software sft,wr n. U 1. 【电脑】软件 My job is writing the software. 我的工作是写软件。 2. (跟随电子设备的)程序材料 Instructions nstrkn n. 1、指令,指示, 用法说明(书), 教育, 指导 2、命令,指示 +to-v +(that) 3、教诲;教导,译,人们为解决问题而制造计算机。早期的计算机解决的是数学和工程问题, 后来计算机着重解决商业应用中的信息处理问题。如今, 计算机还用来控制如汽车发动机、机器人和微波炉等各式各样的机器。计算机系统解决上述这些领域中的任何一个问题都是通过接收输入、处理问题和生成输出来实现的。 计算机系统由硬件和软件组成。硬件是系统的物理部分。硬件一旦设计完毕, 要修改是困难的, 并且花费也大。软件是指挥硬件的程序集合, 比硬件容易修改。计算机之所以有用,是因为它们能解决很多不同类型的问题, 是通用的机器。相对而言, 每种专用机只能解决一类问题。通过为系统配备不同的指令系统, 也就是配备不同的软件, 能用同一硬件去解决不同的问题。,Most computer systems, from the embedded controllers found in automobiles and consumer appliances to personal computers and mainframes, have the same basic organization. Every computer has four basic hardware components： Central processing unit(CPU). Main memory Input devices. Output devices.,embedded adj.1、植入的, 深入的, 内含的 2、嵌入的 3、嵌入式照明设备 organization ,rgnzen n.1. 组织,机构,团体C 2. 组织工作;体制,编制UC 3. 条理,系统U 4. 【生】有机体C,译,大多数计算机系统, 从汽车和日用电器中的嵌入式控制器到个人计算机和大型主机, 都具有相同的基本组成。每台计算机都有如下4种基本硬件部件： 中央处理器; 主存储器; 输入设备; 输出设备。,Fig. 2-1 shows these components in a block diagram. The lines between the blocks represent the flow of information flows from one component to another on the bus, which is simply a group of wires connecting the components. Processing occurs in the CPU and main memory. The organization in Fig. 2-1, with the components connected to each other by the bus, is common. However, the other configurations are possible as well. Computer hardware is often classified by its relative physical size： Small microcomputer; Medium minicomputer; Large mainframe.,configuration,kn,fgjren n. 1. 结构;表面配置, 结构, ,外形 2. （心）形态 3. （天）行星的方位;(地球表面的)外貌,Fig. 2-1 The basic architecture of microcomputer,译,图2-1以一个框图的形式展示了这几种部件。各框之间的连线代表信息流在总线上从一个部件流向另一个部件, 总线简单地说就是连接各部件的一组线缆。处理是在CPU和主存储器中进行的。图2-1中通过总线相互连接的各部件的组成是很常见的。当然, 也可能有其他配置。 计算机硬件常以相对体积大小来分类, 如下所示： 小型计算机; 中型计算机; 大型计算机。,Just the CPU of a mainframe often occupies an entire cabinet. Its input/ output(I/O) devices and memory might fill an entire room. Microcomputers can be small enough to fit on a desk or in a briefcase. As technology advances, amount of processing previously possible only on large machines becomes possible on smaller machines. Microcomputers now can do much of the work that only minicomputers or mainframes could do in the past.,cabinet,kbnt n. 1、(有抽屉或格子的)橱柜, 内阁 2、 内阁，全体阁员 3、私人小房间,密室C adj. 1. 内阁的 2. 私下的,秘密的,译,一台大型机的CPU往往要占用一个机柜。它的输入/输出(I/O)设备和存储器可能塞满一个屋子。微型计算机可以小到能放在桌子上或公文包里。随着技术的进步, 以前只能在大型机上进行的大量处理工作, 现在可以在更小的机器上进行。很多过去只能在小型或大型机上做的工作现在微型计算机都能完成。,The classification just described is based on physical size as opposed to storage size. A computer system user is generally more concerned with storage size because that is a more direct indication of the amount of useful work that the hardware can perform. The speed of computation is another characteristic that is important to the user. Generally speaking, users want a fast CPU and large amounts of storage, but a physically small machine for the I/O devices and main memory.,classification,klsfken n. 1、分类, 分级 2、分类法U 3、类别系统;类别C,storage,stord n. U 1. 贮藏,保管 2. 贮藏库,货栈,仓库 3. 贮藏量,库存量 4. 保管费,栈租 5. 蓄电 6. 存储,记忆,characteristic,krktrstk n. C 1. 特性,特征,特色 2. 【数】(对数的)首数 adj. 1. 特有的,独特的;典型的;表示特性的 +of,译,上面所述的是按照物理尺寸的大小而不是按存储器的大小来分类的。计算机系统用户通常更关心存储器的大小, 因为这更直接地表明硬件所能完成的有效工作量。运算速度对用户来说是另一个重要特性。一般来讲, 用户需要快速的CPU和大容量存储器, 而I/O设备和主存储器的体积则要小。,The CPU,The part of the computer that runs the program (executes program instructions) is known as the processor or central processing unit (CPU). In a microcomputer, the CPU is on a single electronic component. Microprocessor is a processor whose elements have been miniaturized into one or a few integrated circuits. It is a semiconductor CPU and one of the principal components of the microcomputer. The elements of the microprocessor are frequently contained on a single chip or within the same package, but are sometimes distributed over several separate chips.,processor,pruses n. 1. 处理机；处理器；处理程 2. 加工者;制造者 3. 【电脑】信息处理器;处理程序,miniaturize,minitraiz vt. 1.使小型化;使微型化,integrate,intigreit vt. 1. 使成一体,使结合,使合并(+with/into) 2. 使完整,使完善 3. 表示.的总和;表示.的平均值 4. 【主美】使取消(种族)隔离;使(黑人等)获得平等待遇 5. 【数】求.的积分 vi. 1. 成为一体,结合在一起(+with/into) 2. 【主美】取消(种族)隔离;(黑人等)获得平等待遇 3. 【数】求积分,semiconductor,semikndkt n. 物 半导体,译,CPU 处理器或中央处理单元（CPU）是计算机中运行程序（执行程序指令）的部件。微型计算机中，CPU是一个独立的电子部件。微处理器是一种小型化处理器, 其所有元件都在一块或数块集成电路内。它是半导体中央处理器(CPU), 是微型计算机的主要部件。微处理器的元件通常安装在一个芯片上或在同一组件内, 有时也分布在几个芯片上。,The central processing unit has two componentsthe control unit and the arithmetic-logic unit. The control unit tell the rest of the computer system how to carry out a programs instructions. It directs the movement of electronic signals between memorywhich temporarily holds data, instructions, and processed informationand the arithmetic-logic unit. It also directs these control signals between the CPU and input and output devices. In a microcomputer with a micro programmed instruction set, it contains an additional control-memory unit.,control unit 1. 控制单元，控制组件 2. 控制部件 , 控制器 3. 控制装置 arithmetic-logic unit1. 算术逻辑单位 2. 算术逻辑部件 temporarily temprerili adv. 1. 暂时地,临时地，临时性,译,中央处理单元由控制逻辑部件和算术逻辑部件组成。中央处理单元控制计算机系统中的其他部件执行指令。它指示存储器（暂时存储数据、指令、处理信息）和算术逻辑单元之间的信号传递。它还要控制CPU 和输入/输出设备之间的信息传递。在具有微程序控制的指令集的微型计算机中, 它包含附加的控制-存储部件。,The arithmetic-logic unit, usually called the ALU, performs two types of operationsarithmetic and logical. Arithmetic operations are, as you might expect, the fundamental math operations: addition, subtraction, multiplication, and division. Logical operations consist of comparisons. That is, two pieces of data are compared to see whether one is equal to (=), less than () the other.,perform,pf:m vt. 1. 履行;执行;完成;做 2. 演出,表演,演奏 vi. 1. 演出,表演,演奏 (+on/at) 2. (机器)运转;(人)行动,表现Q,译,算术逻辑单元通常称为ALU，通常能够完成算术运算和逻辑运算两种运算。算术运算和你想到的一样，就是一些基本的算术运算：加、减、乘和除。逻辑操作主要是比较。也就是，两组数据进行比较，确定它们是相等(=)、小于()的关系。,The CPU controls the computer. It fetches instructions from memory, supplying the address and control signals needed by memory to access its data. The CPU decodes the instruction and controls the execution procedure. It performs some operations internally, and supplies the address, data, and control signals needed by memory and I/O devices to execute the instruction. Nothing happens in the computer unless the CPU causes it to happen.,access,kses vt. 1. 【电脑】取出(资料);使用;接近 n. 1. 接近,进入;接近的机会,进入的权利;使用U (+to) access broadcasting 向公众开放的节目播送 2. 通道,入口,门路CU (+to) 3. 【书】(病的)发作;(怒气等的)爆发C (+of) in an access of fury 勃然大怒 4. 【电脑】存取;取出U,decode,vt. 1. 译解(密码)，解码 execution n.实行, 完成, 执行 internally adv.在内, 在中心,译,CPU控制整个计算机。它从存储器中取指令, 提供存储器需要的地址和控制信号。CPU对指令译码并且控制整个执行过程。它执行一些内部操作, 并且为存储器 和I/O设备执行指令提供必要的地址、数据和控制信号。除非CPU激发, 否则, 计算机什么事情都不会发生。,Internally, the CPU has three sections. The register sections, as its name implies, includes a set of registers and a bus or other communication mechanism. The registers in a processors instruction set architecture are found in this section of the CPU. The system address and data buses interact with this section of the CPU. The register section also contains other registers that are not directly accessible by the programmer. The relatively simple CPU includes registers to latch the address being accessed in memory and a temporary storage register, as well as other registers that are not a part of its instruction set architecture.,register n.寄存器，记录, 登记簿, 登记, 注册 architecture n.建筑, 建筑学，体系机构,译,CPU内部有三大分区。寄存器区, 顾名思义, 它包括一组寄存器、一条总线或其他通信机制。微处理器指令集结构中的寄存器就属于CPU的这一分区。系统的地址和数据总线与寄存器交互。此分区还包括程序员不能直接访问的一些寄存器。相对简单CPU含有寄存器，用以锁存正在访问的存储器地址, 还有暂存器以及指令集结构中没有的其他寄存器等。,During the fetch portion of the instruction cycle, the processor first outputs the address of the instruction onto the address bus. The processor has a register called the program counter; the CPU keeps the address of the next instruction to be fetched in this register. Before the CPU outputs the address onto the systems address bus, it retrieves the address from the program counter register. At the end of the instruction fetch, the CPU reads the instruction code from the system data bus. It stores this value in an internal register, usually called the instruction register or something similar.,cycle n.周期, 循环 retrieve v.重新得到,译,在指令周期的取指阶段, 处理器首先将指令的地址输出到地址总线上。处理器有一个寄存器叫做程序计数器, CPU将下一条要取的指令的地址存放在程序计数器中。在CPU将地址输出到系统的地址总线之前, 必须从程序计数器中取出该地址。在指令结束前, CPU从系统时局总线上读取指令码, 它把该指令码存储在某个内部寄存器中, 该寄存器通常称作指令寄存器或其他相似的名字,The control unit also generates the signals for the system control bus, such as the READ, WRITE, and the other signals. A microprocessor typically performs a sequence of operations to fetch, decode, and execute an instruction. By asserting these internal and external control signals in the proper sequence, the control unit causes the CPU and the rest of the computer to perform the operations needed to correctly process instructions.,typically adv.代表性地, 作为特色地 assert v.断言, 声称 sequence n.次序, 顺序, 序列,译,控制单元也产生系统控制总线上的信号, 例如READ, WRATE和其他信号等。典型的一个微处理器执行取指令、译指令和执行指令等一系列的操作。通过以正确的顺序激发这些内部或外部控制信号, 控制单元使CPU和计算机的其余部分完成正确处理指令所需要的操作。,This description of the CPU is incomplete. Current processors have more complex features that improve their performance. One such mechanism, the instruction pipeline, allows the CPU to fetch one instruction while simultaneously executing another instruction.,feature n.特征, 容貌, 特色, 特写 performance n.履行, 执行, 成绩, 性能, 表演 pipeline n.管道, 传递途径,译,以上对CPU的描述并不完整。现在的处理器拥有更加复杂的特征以提高其性能。这些机制中有一种是指令流水线技术, 它允许CPU在执行一条指令的同时取出另 一条指令,In this section we have introduced the CPU from a system perspective, but we have not discussed its internal design. We examine the registers, data paths, and control unit, all of which act together to cause the CPU to properly fetch, decode, and execute instructions. Microsequenced CPUs have the same registers, ALUs and data paths as hardwired CPUs, but completely different control units.,本节我们从系统的角度介绍了CPU, 但我们还没有讨论它的内部设计。我们描述了CPU的寄存器、数据通路、控制单元等, 所有部件一起工作使CPU正确地读取、译码和执行指令。微程序CPU具有同硬连线CPU一样的寄存器、ALU和数据通路, 但二者控制单元完全不同。,System Buses,Physically, a bus is a set of wires. The components of the computer are connected to the buses. To send information from one component to another, the source component outputs data onto the bus. The destination component then inputs this data from the bus. As the complexity of a computer system increases, it becomes more efficient (in terms of minimizing connections) at using buses rather than direct connections between every pair of devices. Buses use less space on a circuit board and require less power than a large number of direct connections. They also require fewer pins on the chip or chips that comprise the CPU. The system shown in Figure 2-1 has three buses. The uppermost bus in this figure is the address bus. When the CPU reads data or instructions from or writes data to memory, it must specify the address of the memory location it wishes to access. It outputs this address to the address bus; memory inputs, this address from the address bus and uses it to access the proper memory location. Each I/O devices, such as a keyboard, monitor, or disk drive, has a unique address as well. When accessing an I/O device, the CPU places the address of the device on the address bus. Each device can read the address off of the bus and determine whether it is the device being accessed by the CPU. Unlike the other buses, the address bus always receives data from the CPU; the CPU never reads the address bus.,destination n目的地，目的文件, 目的单元格 uppermost adj.至上的, 最高的, 最主要的 adv.在最上, 最初, 首先 specify vt.指定, 详细说明, 列入清单 unique adj.唯一的, 独特的,译,系统总线 从物理上来说, 总线就是一组导线。计算机的部件就是连在总线上的。为了将信息从一个部件传到另一个部件, 源部件先将数据输出到总线上, 然后目标部件再从总线上接受这些数据。随着计算机系统复杂性的不断增长, 使用总线比每个设备对之间直接连接要有效得多（就减少连接数量而言）。与大量的直接连接相比, 总线使用较少的电路板空间, 耗能更少, 并且在芯片或组成CPU的芯片组上需要较少的引脚。 图2-1所示的系统包括三组总线。最上面的是地址总线。当CPU从存储器读取数据或指令, 或写数据到存储器时, 它必须指明将要访问的存储器单元地址。 CPU将地址输出到地址总线上, 而存储器从地址总线上读取地址, 并且用它来访问正确的存储单元。每个I/O设备, 比如键盘、显示器或者磁盘, 同样都有一个唯一的地址。当访问某个I/O设备时, CPU将此设备的地址放到地址总线上。每一个设备均从总线上读取地址并且判断自己是否就是CPU正要访问的设备。与其他总线不同, 地址总线总是从CPU上接收信息, 而CPU从不读取地址总线。,Data is transferred via the data bus. When the CPU fetches data from memory, it first outputs the memory address on its address bus. Then memory outputs the data onto the data bus; the CPU can then read the data from the data bus. When writing data to memory, the CPU first outputs the address onto the address bus, then outputs the data onto the data bus. Memory then reads and stores the data at the proper location. The processes for reading data from and writing data to the I/O devices are similar. The control bus is different from the other two buses. The address bus consists of n lines, which combine to transmit one n-bit address value. Similarly, the lines of the data bus work together to transmit a single multi-bit value. In contrast, the control bus is a collection of individual control signals. These signals indicate whether data is to be read into or written out of the CPU, whether the CPU is accessing memory or an I/O device, and whether the I/O device or memory is ready to transfer data. Although this bus is shown as bidirectional in Figure 2-1, it is really a collection of (mostly) unidirectional signals. Most of these signals are output from the CPU to the memory and I/O subsystems, although a few are output by these subsystems to the CPU. A system may have a hierarchy of buses. For example, it may use its address, data, and control buses to access memory, and an I/O controller. The I/O controller, in turn, may access all I/O devices using a second bus, often called an I/O bus or a local bus.,transfer vt.转移, 调转, 调任, 传递, 转让, 改变 similar adj.相似的, 类似的 transmit vt.传输, 转送, 传达, 传导, 发射, 遗传, 传播 multi-bit 多位 bidirectional双向的 unidirectional 单向的 Local adj.局部的,译,数据是通过数据总线传送的。当CPU从存储器中取数据时, 它首先把存储器地址输出到地址总线上, 然后存储器将数据输出到数据总线上, 这样CPU就可以从数据总线上读取数据了。当CPU向存储器中写数据时, 它首先将地址输出到地址总线上, 然后把数据输出到数据总线上, 这样存储器就可以从数据总线上读取数据并将它存储到正确的单元中。对I/O设备读写数据的过程与此类似。 控制总线与以上两种总线都不相同。地址总线由n根线构成, n根线联合传送一个n位的地址值。类似地, 数据总线的各条线合起来传输一个单独的多位值。相反, 控制总线是单根控制信号的集合。这些信号用来指示数据是要读入CPU还是要从CPU写出, CPU是要访问存储器还是要访问I/O设备, 是I/O设备还是存储器已就绪要传送数据等等。虽然图2-1所示的控制总线看起来是双向的, 但它实际上(主要)是单向（大多数都是）信号的集合。大多数信号是从CPU输出到 存储器与I/O子系统的, 只有少数是从这些子系统输出到CPU的。 一个系统可能具有分层次的总线。例如, 它可能使用地址、数据和控制总线来访问存储器和I/O控制器。I/O控制器可能依次使用第二级总线来访问所有的I /O设备, 第二级总线通常称为I/O总线或者局部总线。,Instruction Cycle The instruction cycle is the procedure a microprocessor goes through to process an instruction. First the microprocessor fetches, or reads, the instruction from memory. Then it decodes the instruction, determining which instruction it has fetched. Finally, it performs the operations necessary to execute the instruction. (Some people also include an additional element in the instruction cycle to store results. Here, we include that operation as part of the execute function.) Each of these functions-fetch, decode, and execute-consists of a sequence of one or more operations. Lets start where the computer starts, with the microprocessor fetching the instruction from memory. First, the microprocessor places the address of the instruction on to the address bus. The memory subsystem inputs this address and decodes it to access the sired memory location. After the microprocessor allows sufficient time for memory to decode the address and access the requested memory location, the microprocessor asserts a READ control signal. The READ signal is a signal on the control bus, which the microprocessor asserts when it is ready to read data from memory or an I/O device. (Some processors have a different name for this signal, but all microprocessors have a signal to perform this function.) Depending on the microprocessor, the READ signal may be active high (asserted - 1) or active low (asserted - 0).,When the READ signal is asserted, the memory subsystem places the instruction code to be fetched onto the computer systems data bus, The microprocessor then inputs this data from the bus and stores it in one of its internal registers. At this point, the microprocessor has fetched the instruction. Next, the microprocessor decodes the instruction. Each instruction may require a different sequence of operations to execute the instruction. When the microprocessor decodes the instruction, it determines which instruction it is in order to select the correct sequence of operations to perform. This is done entirely within the microprocessor; it does not use the system buses. Finally, the microprocessor executes the instruction. The sequence of operations to execute the instruction varies from instruction to instruction. The execute routine may read data from memory, write data to memory, read data from or write data to an I/O device, perform only operations within the CPU, or perform some combination of these operations.,memory location存储单元 sufficient adj.充分的, 足够的 assert v.断言, 声称 routine n. 程序,例行公事, 常规, 日常事务,译,指令周期 指令周期是微处理器完成一条指令处理的步骤。首先, 微处理器从存储器读取指令, 然后将指令译码, 辩明它取的是哪一条指令。最后, 它完成必要的操作来执行指令（有人认为在指令周期中还要包括一个附加的步骤来存储结果, 这里我们把该操作当作执行功能的一部分）。每一个功能读取、译码和执行都包括一个或多个操作。 当微处理器为存储器留出充足的时间来对地址译码和访问所需的存储单元之后, 微处理器发出一个读（READ）控制信号。当微处理器准备好可以从存储器或是 I/O设备读数据时, 它就在控制总线上发一个读信号。（一些处理器对于这个信号有不同的名字, 但所有处理器都有这样的信号来执行这个功能。）根据微处理器的不同, 读信号可能是高电平有效（信号=1）, 也可能是低电平有效（信号=0）。 读信号发出后, 存储器子系统就把要取的指令码放到计算机的数据总线上, 微处理器就从数据总线上输入该数据并且将它存储在其内部的某个寄存器中。至此, 微处理器已经取得了指令。 接下来, 微处理器对这条指令译码。每一条指令可能要有不同的操作序列来执行。当微处理器对该指令译码是, 它确定处理的是哪一条指令以便选择正确的操作序列去执行。这一步完全在微处理器内完成, 不需要使用系统总线。 最后, 微处理器执行该指令。指令不同, 执行的操作序列也不同。执行过程可以是从存储器读取数据, 写数据到存储器, 读或写数据到I/O设备, 执行CPU内部 操作或者执行多个上述操作的组合。 微处理器从存储器读取数据所执行的操作序列, 同从存储器中去一条指令是一样的。毕竟取指令就是简单地从存储器中读取它。图2-2(a)显示了从存储器中读取数据的操作时序。,Read Cycle To read data from memory, the microprocessor performs the same sequence of operations it uses to fetch an instruction from memory. After all, fetching an instruction is simply reading it from memory. Figure 2-2(a) shows the timing of the operations to read data from memory. In Figure 2-2（a）, notice the top symbol, CLK. This is the computer system clock; the microprocessor uses the system clock to synchronize its operations. The microprocessor places the address onto the bus at the beginning of a clock cycle, a 0/1 sequence of the system clock. One clock cycle later, to allow time for memory to decode the address and access its data, the microprocessor asserts the READ Signal. This causes memory to place its data onto the system data bus. During this clock cycle, the microprocessor reads the data off the system bus and stores it in one of its registers. At the end of the clock cycle it removes the address from the address bus and cancel the READ signal. Memory then removes the data from the data bus, completing the memory read operation.,Fig.2-2(a) Read Cycle,Fig.2-2(b) Write Cycle,Write Cycle The timing of the memory WRITE operation is shown in Figure 2-2(b). The pro
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