计算机导论

1.If the memory cell whose address is 5 contains the value 8, what is the difference between writing the value 5into cell number 6 and moving the contents of cell number 5 into cell number 6?在第一种情况下，地址为6的存储单元结果包含值5；第二章情况下结果包含82.Suppose you want to interchange the values stored in memory cells 2 and3.What is wrong with the followingsequence of steps: *Step 1：Move the contents of cell number 2 to cell number 3.Step2：Move the contents of cell number 3 to cell number 2.Design a sequence of steps that correctly interchanges the contents of these cells.Answer: 2->1; 3->2; 1->3;3.What advantage does a hard-disk system gain from the fact that its disks spin faster than those in a floppy-disksystem?有较快的数据检索速度和较高的传输速率。

4.In the ASCII code, what is the relationship between the codes for an uppercase letter and the same letter inlowercase?除了从低端数第6位对大写字母和小写字母分别是0和1外，两个位模式是相同的。

5.Convert each of the following binary representations to its equivalen ten form:将下列二进制（binary representations）表示转换为等价的十进制（ten form）形式6.Convert each of the following base ten representations to its equivale binary form:将下列十进制（ten representations）表示转换为等价的二进制（binary form）形式7.Convert each of the following two's complement representations to its equivalent base ten form:将下列二进制补码（two's complement representations）转换成等价的十进制8. a. Suppose you XOR the first two bits of a string of bits and then continue down the string by successivelyXORing each result with the next bit in the string. How is your result related to the number of 1s appearing in the string?b. How does this problem relate to determining what the appropriate parity bit should be when coding amessage?Answer：a、如果该串包含偶数个1，那么最后结果是0，否则是1；b、结果是偶校验的校验位值9.Which of the following would require real-time processing?a)Printing mailing labelsb) b. Playing a computer game √c) c. Displaying letters on a monitor screen as they are typed at the keyboard √d) d. Executing a program that predicts the state of next year's economy10.Identify examples of queues. In each case, indicate any situations that violate the FIFO structure.实时处理是指一个程序的执行要与机器的环境里的活动相协调。

交互处理时指一个程序在其执行时人要与他交互。

成功的交互处理需要好的实时特征。

’11.What is the difference between time-sharing and multitasking分时是在单处理器的机器上实现多任务的技术。

12.List the components of a typical operating system and summarize the role of each in a single phrase. *（外壳）：与机器的环境通信（文件管理程序）：协调机器大容量存储器的使用（设备驱动程序）：处理与机器外部设备的通信（存储管理程序）：协调机器主存储器的使用调度程序：协调系统中的进程调遣程序：协调各个进程的ＣＰＵ时间的分配13.Summarize the difference between a program and a process. *Program- a set of directions 指令的集合Process-action of the following those directions 遵循这些指令的动作14.In a time-sharing system, how can high-priority processes be allowed to run faster than others?Dispacher 赋其高优先级--------或给该进程长的时间片Specifications and protocols are publicAllowing vendors to produce compatible products16.What is a router?网络层的互连设备路由器是一台机器；它把两个网络连接成一个互联网。

术语网关通常是指把一个域连接到互联网其余部分的路由器17.What is the purpose of tier-1 and tier-2 ISPs? What is the purpose of access ISPs?Answer：tier-1 and tier-2提供接入Internel的核心服务功能接入服务商提供接入核心的能力18.What is the DNS? *名字服务器，负责将助记符地址转换成IP地址19.What bit pattern is represented by 3.4.5 in dotted decimal notation? Express the bit pattern 0001001100010000using dotted decimal notation.3.4.50000001100000100000001010001001100010000 19.1620.What are the components of the complete Internet address of a machine?一台机器完整的因特网地址由网络标识符和主机地址构成21.What is a URL? A browser?ＵＲＬWWW（万维网）中指定的文档地址Browser-一个程序用于访问超文本，帮助用户存取超文本22.How does the Internet software ensure that messages are not relayed within the Internet forever?每个消息赋予跳数(hop count)23.Summarize the distinctions between a process, an algorithm, and a program. *Answer:Process-activity of execution an algorithm一个进程是执行一个算法的活动program-a representation of an algorithm一个程序一个算法的表示24.In what sense do the steps described by the following list of instructions fail to constitute an algorithm?Step 1. Take a coin out of your pocket and put it on the table.Step 2. Return to Step 1.问题：不确定性—空口袋呢？这里存在两点。

一、这些指令定义了一个不可终止的过程。

但是，事实上，这个过程最终达到这样的状态：你的口袋里在没有硬币。

实际上，这可能是初始状态。

二、这个算法正如所所表示的，她并没有告诉我们在这个情况下该怎么做，也就是说不知道初始状态是什么。

25.The Euclidean algorithm finds the greatest common divisor of two positive integers X and Y by the followingprocess:As long as the value of neither X nor Y is zero, continue dividing the larger of the values by the smaller and assigning X and Y the values of the divisor and remainder, respectively. (The final value of X is the greatest common divisor.)Express this algorithm in our pseudocode.X ←the lager input;Y ← the smaller input;While (Y not zero) doi.X ← Yii.Y ← RemainderGCD ← XZ ←0;X ←1;while (X < 6) do(Z ←Z + X;X←X+ l)to an equivalent routine using a repeat statement.Answer：Z ←0;X ←1;repeat (Z ←Z + X;X←X+ l)Until (X = 6)27.What names are interrogated by the binary search (Figure 5.14) when searching for the name be in the listAlice, Brenda, Carol, Duane, Evelyn, Fred, George, Henry, Irene, Joe, Karl, Larry, Mary, Nancy, and Oliver?----Alice, Brenda, Carol, Duane, Evelyn, Fred, George, Henry, Irene, Joe, Karl, Larry, Mary, Nancy, Oliver28.List the classes Θ(n2), Θ(lg n), Θ(n), and Θ(n3) in decreasing order of efficiency.效率由高到低：Θ(lg n)- Θ(n)- Θ(n2) -Θ(n3)29.In what sense is a program in a third-generation language machine independent? In what sense is it stillmachine dependent?一个用第三代语言编写的程序，从某种意义上说它是独立于机器的，因为它的步骤不是按照诸如寄存器和存储单元地址这样的机器属性来描述的。