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某计算机的主存地址位数为32位,按字节编址。假定数据Cache中最多存放128个主存块,采用4路组相联方式,块大小为64Byte。每块设置了1位有效位“脏(Dirty)”位。要求: (1)分别指出主存地址中标记(Tag)、组号(Index)和块内地址(Offset)三部分的位置和位数。

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One thing that distinguishes the online world from the real one is that it is very easy to find things. To find a copy of The Economist in print, one has to go to a news-stand, which may or may not carry it. Finding it online, though, is a different proposition. Just go to Google, type in "economist" and you will be instantly directed to economist.com. Though it is difficult to remember now, this was not always the case. Indeed, until Google, now the world’s most popular search engine, came on to the scene in September 1998, it was not the case at all. As in the physical world, searching online was a hit-or-miss affair. Google was vastly better than anything that had come before: so much better, in fact, that it changed the way many people use the web. Almost overnight, it made the web far more useful, particularly for nonspecialist users, many of whom now regard Google as the internet’s front door. The recent fuss over Google’s stock market flotation obscures its far wider social significance: few technologies, after all, are so influential that their names become used as verbs. Google began in 1998 as an academic research project by Sergey Brin and Lawrence Page, who were then graduate students at Stanford University in Palo Alto, California. It was not the first search engine, of course. Existing search engines were able to scan or "crawl" a large portion of the web, build an index, and then find pages that matched particular words. But they were less good at presenting those pages, which might number in the hundreds of thousands, in a useful way. Mr Brin’s and Mr Page’s accomplishment was to devise a way to sort the results by determining which pages were likely to be most relevant. They did so using a mathematical recipe, or algorithm, called PageRank. This algorithm is at the heart of Google’s success, distinguishing it from all previous search engines and accounting for its apparently magical ability to find the most useful web pages. Untangling the web PageRank works by analysing the structure of the web itself. Each of its billions of pages can link to other pages, and can also, in turn, be linked to. Mr Brin and Mr Page reasoned that if a page was linked to many other pages, it was likely to be important. Furthermore, if the pages that linked to a page were important, then that page was even more likely to be important. There is, of course, an inherent circularity to this formula--the importance of one page depends on the importance of pages that link to it, the importance of which depends in turn on the importance of pages that link to them. But using some mathematical tricks, this circularity can be resolved, and each page can be given a score that reflects its importance. The simplest way to calculate the score for each page is to perform a repeating or "iterative" calculation (see article). To start with, all pages are given the same score. Then each link from one page to another is counted as a "vote" for the destination page. Each page’s score is recalculated by adding up the contribution from each incoming link, which is simply the score of the linking page divided by the number of outgoing links on that page. (Each page’s score is thus shared out among the pages it links to.) Once all the scores have been recalculated, the process is repeated using the new scores, until the scores settle down and stop changing (in mathematical jargon, the calculation "converges"). The final scores can then be used to rank search results: pages that match a particular-set of search terms are displayed in order of descending score, so that the page deemed most important appears at the top of the list. We can infer from the 1st paragragh that by "hit-or-miss" it is meant ______.

A. before Google, searching online was impossible
B. before Google, searching online lacked accuracy
C. before Google, searching online was difficult
D. Google is easy to use

假令瘦人,脐下有悸,吐涎沫而癫眩,此______也,______主之。

假设:某8位机的地址码为16位,主存按字节编址,其中最高8KB主存空间为系统BIOS程序区,其余为用户程序区。现有4K×4位的ROM芯片和8K×4位的SRAM芯片。问:该机所允许的最大主存空间是多少构建该机所允许的最大空间的主存,需用上述规格的ROM芯片和SRAM芯片各多少

患儿,男,6岁。突发神志丧失,手中持物失落,所持之物落地后即醒。 该疾病典型的脑电图表现为

A. 双颞侧棘波规律性和对称性发放
B. 3周/s棘—慢波规律性和对称性发放
C. 双颞侧慢波规律性和对称性发放
D. 3周/s尖波规律性和对称性发放
E. 正常脑电图

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