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从下面提供的答案中选出应填入下列英文语句中______内的正确答案。
In recent years, one of the more popular topics for panel discussions at computer conferences and trade(1)has been the "RISC versus CISC" debate.
RISC processors feature a small number of instructions that each executes in(2)machine cycle. CISC processors use complex instructions that can take several cycles to execute.
The RISC versus CISC debate won't be decided by panel discussion; it will be won in the marketplace. And the deciding factor may have little to do with the(3)ofinstructions and registers and more to do with parallelism.
Since their conception, RISC processors have been evolving toward microparallelism. Incorporating parallel-processing features(4)the processor, RISC processors feature pipelining, whereby many instructions can be decoded while one instruction executes. RISC processors, however, are moving toward pipelines for each unit of the processor.
CISC processors also employ pipelining. They have many integer instructions that execute in one cycle, but the varying execution times of CISC instructions(5)the effectiveness of parallelism.
提供的答案：
(1) union (2) two (3) numbers (4) between (5) limit
(6) contents (7) shows (8) one (9) within (10) enhance
选出应填入下面一段英语中______内的正确答案。
Since the time of John von Neumann, the basic conceptual model used to think about computers and programs has(1)unchanged, in(2)of many advances in both hardware and software technology. In the(3)that von Neumann proposed, the basic instruction cycle is for the processor to fetch the instruction pointed at by the program counter,(4)the program counter, and then execute the instruction. Because instructions are executed strictly sequentially, there is little inherent parallelism, and(5)opportunity to employ large numbers of processors to gain speed.
供选择的答案：
(1) small (2) big (3) add (4) little (5) model
(6) remained (7) style (8) increase (9) stead (10) spite
(11) already (12) period (13) formula (14) decrease (15) not
Parallel Computer Models
并行模式
Parallel processing has emerged as a key enabling technology in modern computers, driven by the ever-increasing demand for higher performance, lower costs, and sustained productivity in real-life applications. Concurrent events are taking place in today's high- performance computers due to the common practice of multiprogramming, multiprocessing, or multicomputing.
Parallelism appears in various forms, such as lookahead, pipelining, vectorization, concurrency, simultaneity, data parallelism, partitioning, interleaving, overlapping, multiplicity, replication, time sharing, space sharing, multitasking, multiprogramming, multithreading, and distributed computing at different processing levels.
In this part, we model physical architectures of parallel computers, vector super- computers[1], multiprocessors, multicomputers, and massively parallel processors. Theoretical machine models are also presented, including the parallel random-access machines (PRAMs)[2]and the complexity model of VLSI (very large-scale integration) circuits. Architectural development tracks are identified with case studies in the article. Hardware and software subsystems are introduced to pave the way for detailed studies in the subsequent section.
The State of Computing
Modern computers are equipped with powerful hardware facilities driven by extensive software packages. To assess state-of-the-art[3]computing, we first review historical milestones in the development of computers. Then we take a grand tour of the crucial hardware and software elements built into modern computer systems. We then examine the evolutional relations in milestone architectural development. Basic hardware and software factors are identified in analyzing the performance of computers.
Computer Development Milestones
Computers have gone through two major stages of development: mechanical and electronic. Prior to 1945, computers were made with mechanical or electromechanical parts. The earliest mechanical computer can be traced back to 500 BC in the form of the abacus used in China. The abacus is manually operated to perform decimal arithmetic with carrying propagation digit by digit.
Blaise Pascal built a mechanical adder/subtractor in France in 1642. Charles Babbage designed a difference engine in England for polynomial evaluation in 1827. Konrad Zuse built the first binary mechanical computer in Germany in 1941. Howard Aiken[4]proposed the very first electromechanical decimal computer, which was built as the Harvard Mark I[5]by IBM in 1944. Both Zuse's and Aiken's machines were designed for general-purpose computations.
Obviously, the fact that computing and communication were carried out with moving mechanical parts greatly limited the computing speed and reliability of mechanical computers. Modern computers were marked by the introduction of electronic components. The moving parts in mechanical computers were replaced by high-mobility electrons in electronic computers. Information transmission by mechanical gears or levers was replaced by electric signals traveling almost at the speed of light.
Computer Generations
Over the past five decades, electronic computers have gone through five generations of development. Each of the first three generations lasted about 10 years. The fourth generation covered a time span of 15 years. We have just entered the fifth generation with the use of processors and memory devices with more than 1 million transistors on a single silicon chip.
The division of generations is marked primarily by sharp changes in hardware and software technologies. Most features introduced in earlier generations have been passed to later generations. In other words, the latest generation computers have inherited all the nice features and eliminated all the bad ones found in previous generations.
Elements of Modern Computers
Hardware, software, and programming elements of a modern computer system are briefly introduced below in the context of parallel processing.
Computing Problems
It has been long recognized that the concept of computer architecture is no longer restricted to the structure of the bare machine hardware. A modern computer is an integrated system consisting of machine hardware, an instruction set, system software, application programs, and user interfaces. These system elements are depicted in Fig. 1. The use of a computer is driven by real-life problems demanding fast and accurate solutions. Depending on the nature of the problems, the solutions may require different computing resources.
For numerical problems in science and technology, the solutions demand complex mathematical formulations and tedious integer or floating-point computations. For alphanumerical problems in business and government, the solutions demand accurate transactions, large database management, and information retrieval operations.
For artificial intelligence (AI) problems, the solutions demand logic inferences and symbolic manipulations. These computing problems have been labeled numerical computing, transaction processing, and logical reasoning. Some complex problems may demand a combination of these processing modes.
Algorithms and Data Structures
Special algorithms and data structures are needed to specify the computations and communications involved in computing problems. Most numerical algorithms are deterministic, using regularly structured data. Symbolic processing may use heuristics or nondeterministic searches over large knowledge bases.
Problem formulation and the development of parallel algorithms often require interdisciplinary interactions among theoreticians, experimentalists, and computer programmers. There are many books dealing with the design and mapping of algorithms or heuristics onto parallel computers. In this article, we are more concerned about the resources mapping problems than the design and analysis of parallel algorithms.
Hardware Resources
The system architecture of a computer is represented by three nested circles on the right in Fig. 1. A modern computer system demonstrates its power through coordinated efforts by hardware resources, an operating system, and application software. Processors, memory, and peripheral devices form the hardware core of a computer system. We will study instruction-set processors, memory organization, multiprocessors, supercomputers, multicomputers, and massively parallel computers.
Special hardware interfaces are often built into I/O devices, such as terminals, workstations, optical page scanners, magnetic ink character recognizers, modems, file servers, voice data entry, printers, and plotters. These peripherals are connected to mainframe computers directly or though local or wide-area networks.
In addition, software interface programs are needed. These software interfaces include file transfer systems, editors, word processors, device drivers, interrupt handlers, network communication programs, etc. These programs greatly facilitate the portability of user programs on different machine architectures.
Operating System
An effective operating system manages the allocation and deal-location of resources during the execution of user programs. We will study UNIXE[6]extensions for muhiprocessors and muhicomputers later. Mach/OS kernel and OSF/1[7]will be specially studied for muhithreaded kernel functions, virtual memory management, file subsystem, and network communication services. Beyond the OS, application software must be developed to benefit the users. Standard benchmark programs are needed for performance evaluation.
Notes
[1] vector super-computers: 向量巨型机体系机构。向量巨型计算机的体系机构，目前大多数仍为多流水线结构，也有的采用并行处理机构。
[2] parallel random-access machines(PRAMs)：并行随机存取机器具有任意多个处理器，以及分别用于输入、输出和工作的存储器的机器模型。
[3] state-of-the-art：最新技术水平；当前正在发展的技术，或者在当前应用中保持领先地位的技术。
[4] Howard Aiken: Mark I计算机的设计者。
[5] Harvard Mark I：哈佛Mark I计算机。Mark I计算机是一种在30年代末40年代初由(美国)哈佛大学的Howard Aiken设计并由IBM公司制造的机电式计算器。
[6] UNIX：UNIX操作系统。
[7] Mach/OS kernel and OSF/1：Mach操作系统/OS操作系统，Kernel核心程序。在操作系统中，实现诸如分配硬件资源、进程调度等基本功能的程序，是与硬件机器直接打交道的部分，始终驻留内存。OSF/1开放软件基金会/1。
Choose the best answer for each of the following:
How Green Is Your Computer？
您的计算机环保吗？
Reusable big handbag？ Check. Prius？ Check. Rooftop solar panels？ Check[1]. In the bid to secure your green bragging rights, you have the usual suspects covered.
But what about your personal computer？
After all, the object that, via the Internet, can provide you with more information on how to lead an environmentally sound life can also be one of the things that contributes to the very same problem.
Consider the following: A standard-issue PC, left on all the time, which is a not- uncommon situation, consumes 746 kilowatts per hour a year, according to estimates from the U. S. Environmental Protection Agency.[2]By comparison, a refrigerator uses about 500 kilowatts a year. Surely there are things that users can do to reduce their computer's environmental footprint. Read on to learn ways to run your PC more efficiently, make environmentally-intelligent purchasing decisions and to dispose of an old computer properly.
Power Corrupts
The first piece of advice is the simplest: Don't leave your computer on all the time. Shutting it down at night should reduce its power consumption by around 500 kilowatts annually. In addition, your computer should be set to go to sleep after periods of inactivity. Different parts of your system can be set to sleep at different times: Setting your energy-saving preferences to put your hard drive to sleep after 15 minutes of inactivity is a good benchmark; your entire computer, which takes more time to wake up, should be set to go to sleep after 30 minutes.
And dispose of your screensaver. Screensavers can use your hard drive to power up and photo screensavers require the extra use of a graphics card, which means you' ll have the hard drive, graphics card and monitor all in use.
Screensavers are "a throwback from the days of really old-school CRT monitors[3]," Barbara Grimes, spokeswoman for the Climate Savers Computing Initiative[4], said of cathode-ray tubes. "It's never been an energy-saving feature. "
There's also the issue of "phantom" or "vampire" power[5]: Just because your computer or laptop is shut down doesn't mean it's not using energy. Almost every piece of electronics uses power even when it is turned off. For example, your television turns on instantly because it is actually a little bit on already. In the case of your desktop, your computer stays in standby mode so it can keep data in its memory, its clock accurate and other functions. This means the average desktop PC wastes half its power.
To combat the vampires, take your computer (and peripherals) and plug it into a master power strip like the Smart Strip Power Strip[6], which can sense which devices have been turned off and then cut all power to them.
Finally, download a free power-management tool. These applications will show you how much energy you can save by adjusting various settings and will make those adjustments for you in one click. Google's Energy Saver[7]will, in addition, show you the collective energy savings of all users of the product; it also integrates into the Google's own Desktop application. Verdiem's Edison software[8], shows users estimated annual savings in terms of money, energy and carbon dioxide emissions. Edison's power management tool lets users choose how aggressive they want their energy savings to he by letting them slide the bar towards or away from the "save more" or "save less" tabs.
Out with the Old？
If you do decide to purchase a new computer, make sure that you choose both a computer and monitor that are Energy Star[9]computer. Energy Star computers must meet energy-use guidelines established by the environmental agency in three areas: standby, active, and sleep modes.
The Electronic Product Environmental Assessment Tool[10], or Epeat, is another environmental certification that evaluates electronic products according to 51 environmental criteria. To qualify for Epeat registration, the product must meet all 51.
In general, laptops are greener than desktops because they have been designed with power sensitivity.in mind, so they tend to use less power when plugged in than desktops. But desktops are easier to upgrade, and therefore may last longer.
Newer computers tend to be more energy efficient than older models. For example, Energy Star-qualified computers starting from July 2007 come with power management preenabled.
As for whether Macs[11]are greener than Pcs？ "It's system by system," said Grimes, the Climate Savers Computing Initiative spokeswoman. "Apple[12]is one manufacturer and when you say PC, there are dozens. They' re all using Intel processors or AMD processors. Apple is not using a proprietary processor anymore so they' re getting a lot more similar at the hardware level. "
One place where there is a difference is in how certain manufacturers' products are made. Apple, for example, has said it will "completely eliminate the use of polluting materials in its products, and arsenic in the glass of flat-panel displays by the end of 2008. " Unfortunately, that effort has not spread as quickly across the industry as some would like.
"I wish I could say that a lot of companies have eliminated their chemicals or had made some significant improvements, but that's just not where the industry is. " said Barbara, national coordinator of the Electronics Take Back Coalition.[13]
Reduce, Reuse, Recycle
When it comes to recycling your computer, picking the right program is key. If done right, recyclers should reuse the parts they can and manage waste responsibly, which means making sure that parts don't go to countries with poor eco-track records, and that items that do get exported (like circuit boards and leaded glass) to green-friendly sites.
In 2005, used or unwanted electronics amounted to about 1.9 million to 2.2 million tons of waste. Of that number, about 1.7 million tons were disposed of in landfills, and only 345,000 to 379,000 tons were recycled, according to the environmental agency.
The problem is that it's hard to figure out who's dumping and who's not. "There's no such certification program," said Barbara, "which would help promote responsible recycling and green design in the electronics industry. " Her organization, Computer Take Back, conducts initial screenings. Will people know 100 percent？ No, but it's a start.
Computer manufacturers like Apple, Hewlett Packard[14]and Sony[15]offer recycling programs, but Dell goes even further: It will recycle any Dell[16]brand product-no matter when it was bought-free (including pick up). Dell will also pick up other product brands for free if the consumer purchases a new Dell. Concerning manufacturer recycling programs, Kyle added that with a number of manufacturers, "you have to either pay them or you have to buy a new computer to get them to take your old PC back for free. There's a huge disconnect between what people want to do and what they can do, and that's where the manufacturers need to step up. "
Notes
[1] Reusable big handbag？ Check. Prius？ Check. Rooftop solar panels？ Check. In the bid to secure your green bragging rights, you have the usual suspects covered. Prius,普锐斯汽车(一汽丰田)，世界首款混合动力车。在仅利用电动机驱动时对环境没有任何污染；而且在减速、制动和下坡时还能回收能量以供再利用。
译文：你的大手提包可以多次使用吗？请检查。开的是普锐斯汽车吗？请检查。屋顶有太阳能板呢？请检查。为了确保你享有的环保权利，应当注意这些方面。
[2] U.S．Environmental Protection Agency美国环境保护署，简称EPA，成立于1970年，总部设在华盛顿。其任务是为人类提供更清洁和健康的自然环境，制订战略计划，年度报告和政策方针，在国家的环境科学及相关调查、教育和评估方面具有领导地位。
[3] CRT monitor映像管显示器，是一种使用阴极射线管(Cathode Ray Tube)的显示器。
[4] Climate Savers Computing Initiative电脑产业拯救气候计划。是一个国际信息与通讯产业环保组织，一个以计算机节能化为目标的非营利性团体。
[5]“phantom”or“vampire”power“幻影”电源或“吸血鬼”电源，指电器在被关掉后的能耗。
[6] Smart Strip Power Strip 一种智能型电源线，一旦计算机、屏幕、打印机或DVD进入省电模式，这种电源线会自动侦测到此状态，然后自动断电。
[7] Google's Energy Saver使用Google桌面的人可以免费下载Energy Saver这一小工具，它适用于Windows XP和Vista，可以为用户启用并优化显示器、硬盘和电脑的电源管理设置，还能显示您节省的电量，以及使用该小软件的人共同节省的电量。
[8] Verdiem's Edison software美国编程设计公司Verdiem推出的一款计算机节能软件Edison，用来降低个人电脑的耗电量，它能深入计算机操作系统，监控用电量，把系统调整到最“省电”的模式，还能帮用户设定省电功能，计算出节省了多少电费，少排放了多少二氧化碳等。
[9] Energy Star能源之星。1992年由美国环保署(EPA)启动的一项主要针对消费性电子产品的能源节约计划。在PC电源、显示器或是其他电器产品等上面常会见到“Energy Star”标志，表示其通过了美国环保署的低功耗认证，体现了产品良好的节能性能。
[10] Electronic Product Environmental Assessment Tool(美国)电子产品环境影响评价工具，简称EPEAT，是用来对电子产品在其寿命周期中就环境造成的影响进行评估的工具，是美国政府为了满足日益增长的大型机构采购绿色电子产品的需求而设计的。EPEAT由一系列产品评估标准和产品应用、维护管理系统两部分构成。
[11] Mac苹果机，苹果电脑。苹果电脑公司(Apple)于1984年成功推出Machintosh(简称Mac)个人电脑，产生了极大反响。苹果电脑在PC历史上是一座丰碑，以丰富的图形界面改变了单调的文字界面，以灵活的鼠标操纵取代了呆板的键盘控制，一时间畅销世界各地，但近年来市场份额出现下降。
[12] Apple苹果电脑公司，是美国著名的老牌计算机公司，成立于1977年，是个人电脑最早的倡导者和著名生产商。它所生产的苹果系列电脑，包括iMac，PowerMac，ibook，Powerbook等产品线的众多硬件产品，一直是个人电脑市场的主流产品之一，并曾提出过很多新概念，其产品也掀起过多次流行潮，风行一时。
[13] Electronics Take Back Coalition(美国)电子产品回收联盟。位于旧金山，致力于促进和推广消费类电子产品的回收。
[14] Hewlett Packard惠普公司。世界最大的计算机公司之一，该公司制造的产品正被个人使用或用于工业、商业、工程、科学和教育等领域。
[15] Sony索尼公司，创立于1946年5月，总部在日本东京，为横跨电子、金融、娱乐领域的世界巨擘。
[16] Dell戴尔公司。总部设在德克萨斯州奥斯汀，是全球领先的IT产品及服务提供商，其业务包括帮助客户建立自己的信息技术及互联网基础架构。
