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1、1We have learned that all computers have similar capabilities and perform essentially the same functions, although some might be faster than others. We have also learned that a computer system has input, output, storage, and processing components; that the processor is the “intelligence” of a comput
2、er system; and that a single computer system may have several processors. We have discussed how data are represented inside a computer system in electronic states called bits. We are now ready to expose the inner workings of the nucleus of the computer system the processor. 我们已经知道，所有的计算机都具有相似的能力，并且在
3、本质上执行相同的功能，尽管一些可能会比另一些快一点。我们也知道，一个计算机系统具有输入，输出，存储和处理部件；处理器是一个计算机系统智能核心，并且一个计算机系统可以有许多个处理器。我们已经讨论过如何在计算机系统内部，用被称作“位”的电子状态来表现数据，现在我们要弄明白计算机系统的核心，即处理器，的内在的工作方式。The internal operation of a computer is interesting, but there really is no mystery to it. The mystery is in the minds of those who listen to h
4、earsay and believe science-fiction writer. The computer is a nonthinking electronic device that has to be plugged into an electrical power source, just like a toaster or a lamp.计算机的内部操作很有意思，但确实没有什么神秘可言。所谓的神秘只是存在于那些听信传闻和相信科幻小说作家的人的意识中。计算机就是一种没有思想的需要接通电源的电子设备而已，与烤面包机和台灯差不多。Literally hundreds of differ
5、ent types of computers are marketed by scores of manufacturers 1. The complexity of each type may vary considerably, but in the end each processor, sometimes called the central processing unit or CPU, has only two fundamental sections: the control unit and the arithmetic and logic unit. Primary stor
6、age also plays an integral part in the internal operation of a processor. These three primary storage, the control unit, and the arithmetic and logic unit work together. Lets look at their functions and the relationships between them.不加夸张地讲，市场上有几百种不同类型的计算机在销售.每种电脑在复杂性上可能有很大区别，但归根结底,每种处理器，有时称为中央处理器即c
7、pu，只有两个基本部分:控制单元和计算逻辑单元.主内存在处理器内部操作中也是一个不可缺少的部分.这三个部件-主内存，控制单元和计算逻辑单元-一起工作.然我们看看它们(各自的)功能和它们之间的联系。 Unlike magnetic secondary storage devices, such as tape and disk, primary storage has no moving parts. With no mechanical movement, data can be accessed from primary storage at electronic speeds, or cl
8、ose to the speed of light. Most of todays computers use DRAM (Dynamic Random-Access Memory) technology for primary storage. A state-of-the-art DRAM chip about one eighth the size of a postage stamp can store about 256,000,000 bits, or over 25,600,000 characters of data!主存与其他的辅助存储器（如：磁带、硬盘）不一样的是，主存不含
9、有运转部件。由于没有机械运转的需要，主存种数据访问可以达到电子的速度，或接近于光速。当今计算机的主存大多数使用DRAM（动态随机存取存储器）技术。目前最新的工艺水平是：一块只有大约1/8张邮票大小的DRAM芯片却可以存储大约256,000,000位，约25,6000,000个字符的数据。Primary storage, or main memory, provides the processor with temporary storage for programs and data. All programs and data must be transferred to primary s
10、torage from an input device (such as a VDT) or from secondary storage (such as a disk) before programs can be executed or data can be processed. Primary storage space is always at a premium; therefore, after a program has been executed, the storage space it occupied is reallocated to another program
11、 awaiting execution.主存储器，也就是说内存，用于为处理器暂时存放程序和数据。所有的程序和数据在被操作之前必须从输入设备（如VDT）或者辅助存储器转存到主存储器中。主存储器存储容量通常是相当有限的，因此，在一个程序执行结束，它所占用的存储空间必须被重新分配给其它正在等待执行操作的程序。Figure 1-1 illustrates how all input/output (I/O) is “read to” or “written from” primary storage. In the figure, an inquiry (input) is made on a VDT
12、. The inquiry, in the form of a message, is routed to primary storage over a channel (such as a coaxial cable). The message is interpreted, and the processor initiates action to retrieve the appropriate program and data from secondary storage 3.The program and data are “loaded”, or moves, to primary
13、 storage from secondary storage. This is a nondestructive read process. That is, the program and data that are read reside in both primary storage (temporarily) and secondary storage (permanently). The data are manipulated according to program instructions, and a report is written from primary stora
14、ge to a printer.图 1-1描述了输入/输出设备与主存储器间的读和写过程。在图中，VDT发出一个输入请求，请求是以消息模式通过通道（如同轴电缆）发送到主存储器。这个查询被解释，处理器发起操作从辅助存储器中调用合适的程序和数据。程序和数据从辅助存储器传送到主存储器中，这是一个非破坏性的读取过程，也就是说，程序和数据同时存在于主存（临时保存）和辅助存储器（永久保存）中。根据程序指令的指示，处理器对数据进行操作，并从主存传送一份报告到打印机。A program instruction or a piece of data is stored in a specific primary
15、storage location called an address. Addresses permit program instructions and data to be located, accessed, and processed. The content of each address is constantly changing as different programs are executed and new data are processed.程序指令和数据是存储在主存中一个特殊的位置，称为地址空间。通过地址空间可以实现计算机对程序指令和数据的定位、访问和处理。地址空间
16、的内容是经常变化的，这是由于计算机一直在执行不同的程序和数据。Another name for primary storage is random-access memory, or RAM. A special type of primary storage, called read-only memory (ROM), cannot be altered by the programmer. The contents of ROM are “hard-wired” (designed into the logic of the memory chip) by the manufacturer and can be “read only”. When you turn on a microcomputer system, a program in ROM automatically readies the computer s
