问题 单项选择题

若某分页管理的虚拟存储器共有8个页面,每页为1024B,实际主存为 4096B,采用页表法进行地址映像。若页表的内容如表1-2所示,则发生页面失效的全部虚页号为 (65) ,虚拟地址1023所对应的主存实地址页内偏移地址为 (66) ,主存实地址为 (67)
表1-2 页表的内容

虚页号01234567
实页号31232100
装入位11001010

A.656
B.1023
C.2047
D.4095

答案

参考答案:D

解析: 分页的基本思想是把程序的逻辑空间和内存的物理空间按照同样的大小划分成若干页面,以页面为单位进行分配。
在页式存储管理中,系统中虚地址是一个有序对(页号,位移)。在本题中,共有8个页面,每页为1024B,则页号为高3位,页内地址(位移)为低 10位。实际主存为4096B,所以实存为4页。
系统为每一个进程建立一个页表,其内容包括进程的逻辑页号与物理页号的对应关系、装入状态等。如果该页面已被分配,则装入位置1,否则置0。在本题所给的页表中,虚页号为2、3、5、7的装入位为0,这就是发生页面失效的全部虚页号。
虚拟地址1023所对应的二进制数为0001111111111,因此其虚页号为0,页内偏移地址为1023。根据页表,其对应的实页号为3,即主存实地址为4095。

选择题
填空题


In the following passage, there are 25 blanks representing words that are missing from the context. You are to put back in each of the blanks the missing word. Write your answers on the ANSWER SHEET. The time for this section is 25 minutes.
Some consumer researchers distinguish (1) "rational" motives and "emotional" (or "non-rational") motives. They use the term "rationality" (2) the traditional economic sense that assumes (3) consumers behave rationally when they carefully consider all alternatives (4) choose those that give them the greatest utility (i.e., satisfaction). (5) a marketing context, the term "rationality" implies that the consumer selects goods based (6) totally objective criteria, such (7) size, weight, price, and so on. "Emotional" motives imply the selection of goods (8) to personal or subjective criteria—the desire (9) individuality, pride, fear, affection or status.
The assumption underlying this distinction is (10) subjective or emotional criteria do not maximize utility or satisfaction. (11) , it is reasonable to assume that consumers always attempt to select alternatives that, (12) their view, serve to maximize satisfaction. Obviously, the assessment of satisfaction is a very personal process, based (13) the individual’s own needs as (14) as on past behavioral, social, and learning experiences. What may appear (15) irrational to an outside observer may be perfectly rational (16) the context of the consumer’s own psychological field. For example, a product purchased to enhance one’s self-image (such as a fragrance) is a perfectly rational form of consumer behavior. (17) behavior did not appear rational to the person who undertakes it (18) the time that it is undertaken, obviously he or she would not do it. (19) the distinction between rational and emotional motives does not appear to be warranted.
Some researchers go so far (20) to suggest that emphasis (21) "needs" obscures the rational, or conscious, nature of most consumer motivation. They claim that consumers act consciously (22) maximize their gains and minimize their losses; that they act not (23) subconscious drives but from rational preferences, (24) what they perceive to be (25) their own best interests.