(71) In order to append a standard output to an existing file, which of the following operators is used in the UNIX system? ____.

　　A) | B) & C) > D) >>

　　(72) Consider the following figure, where the shaded parts represent already assigned blocks of memory, and the unshaded parts represent free blocks. (2分) If there is a request for 40KB of memory and the best-fit algorithm is used, then the beginning address of memory that is allocated in response to the request is ____. 　　　　　 　A) 100KB B) 190KB C) 330KB D) 410KB

　　(73) On a certain disk, there are 200 tracks, numbered 0-199, the current position of the disk head is track 53. If the shortest-seek-time-first scheduling algorithm is used when the tracks

　　98, 183, 37, 122, 14, 124, 65, 67

　　are requested, then the head-moving sequence that results will be (2分)

　　A) 65, 67, 37, 14, 98, 122, 124, 183

　　B) 65, 67, 37, 98, 122, 124, 183, 14

　　C) 65, 67, 98, 122, 124, 183, 37, 14

　　D) 98, 183, 37, 122, 14, 124, 65, 67

　　(74) Whant operation on relations R and S produces the relation shown below?____.

　　{tuple│tuple∈R۸tuple∈\ S}

　　A) Union B) Difference C) Intersection D) Division

　　(75) When embedding SQL in a C language program, the prefix that should be added to all SQL statements in order to distinguish SQL statements from the host language statements is____.

　　A) ： B) EXEC C) EXEC SQL D) SQL

　　(76) In the ORACLE system,sets of SQL statements and control flow statements that have been named,compiled,and stored tn the database are referred to as stored____.

　　A) batches B) procedures C) triggers D) transactions

　　(77) Which of the following statements about object oriented databases is NOT correct? ____. (2分)

　　A) Each object has a unique object identity in the system.

　　B) Encapsulation and inheritance are two important features of object oriented databases.

　　C) A subclass can inherit the attributes and methods of all its superclasses.

　　D) A superclass includes the attributes and methods of all its subclasses.

　　(78) In the design phase of software engineering, decomposition of the program into modules should follow the principles of ____.

　　A) low cohesion with low corpling 　　B) low cohesion with high coupling

　　C) high cohesion with low coupling 　D) high cohesion with high coupling

　　(79) Specifications for software should contain&nbs p;several components, e.g., specifications of

　　information flow,

　　user interface,

　　functional requirements, and

　　design constraints.

　　Two other important components are specifications of the____. (2分)

　　A) methods of testing and ways to obtain quality assurance

　　B) criteria for testing and ways to obtain quality assurance

　　C) methods of testing and criteria for function assurane

　　D) criteria for testing and methods of function assurance

　　(80) Which of the following statements about testing software with data is (are) true?____.

　　I. The primary purpose of such testing is to find errors.

　　II. Such testing can demonstrate the existence of errors but cannot

　　demonstrate the absence of errors.

　　A) Neither B) Ⅰ only C) Ⅱ only D) Ⅰ and Ⅱ

　　(81) The type of testing done during software implementation and beforemodule integration is called ____.

　　A) unit testing B) beta testing

　　C) system testing D) acceptance testing

　　(82) Which of the following is (are) true about software portability? ____.

　　I. Using a high-level language that conforms to an ISO standardguarantees portability across the range of machines that support the language.

　　II. Portability is guaranteed across all machines that have the same instruction set and operating system. (2分)

　　A) Neither B) Ⅰ only C) Ⅱ only D) Ⅰ and Ⅱ

　　(83) A memory-memory, machine instruction for a certain machine has the following format.

　　(Such an instruction is similar to a register-register instruction

　　except that the operands are displaced addresses in memory.)

　　opcode meml displ1 mem2 displ2

　　Which of the following could be an assembly lanuage instruction that would be translated into a memory-to-memory instruction for this machine? ____.

　　A) ADD 10(R1), 20(R2) B) ADD(10R1), (20R2)

　　C) ADD R1, 10(R2), 20 D) ADD R1, 10, 20(R2)

　　(84) In a certain cache system, the modified cache block is written to main memory only when the block is replaced. All of the following are used to describe this policy EXCEPT____.

　　A) store-in B) write-back C) copy-back D) write-through

　　(85) When an amount of memory is requested that is less than the size of a page, but a full page is allocated, the r esulting waste of memory is called ____.

　　A) external fragmentation B) internal fragmentation

　　C) inaccessible page faults D) inaccessible garbage

　　(86) The time that the CPU spends on a given program can be computed using all of the following expressions EXCEPT ____. (2分)

　　A) (CPU clock cycles for the program)*(clock cycle time)

　　B) CPU clock cycles for the program

　　clock rate

　　C) (Instruction count)*CPI

　　clock rate

　　D) (CPU clock cycles for the program)*CPI

　　clock rate

　　(87) The methods used in Asynchronous Transfer Mode (ATM) are switch technology and which of the following is used to describe this mode?____.

　　A) cell exchange B) packet exchange

　　C) message exchange D) information exchange

　　(88) In a data communication system, the transport media with the widest frequency band and best reliability is the ____.

　　A) telephone line B) coaxial cable

　　C) radio channel D) fiber optic cable

　　(89) Which of the following statements about the Internet is (are) true?____.　　　 I. It is possible to have multiple names corresponding to the same IP address. II. All host names must be registered with an Internet-wide central registry.

　　A) Neither B) Ⅰ only C) Ⅱ only D) Ⅰ and Ⅱ

　　(90) According to the principle of CRC calculation, given a frame-bit series M =11100111 and the multiple-term formula, frame-bit series generated by the CRC G =110011, then the CRC is ____.(2分)

　　A) 111101 B) 00011 C) 11010011 D) 1101001

　　二、論述題(兩個論述題可任選其一,并只選其一,多選無效,滿分30分。)

　　論述題 1

　　局域網是當前計算機網絡研究與應用的一個熱點,而符合IEEE 802.3標準的傳統Ethenet(MAC層采用CSMA/CD方法,物理層采用 10BASE-T標準)應用最為廣泛。隨著網絡應用的發展,以及大型信息系統與多媒體技術的應用,人們對局域網性能提出了越來越高的要求,出現了符合 100BASE-T標準的Fast Ethernet、交換局域網Switching LAN與ATM等高速局域網產品。盡管高速局域網技術發展十分迅速,但是Ethernet仍然會被廣泛地使用。今后的網絡應該是傳統Ethernet、FastEthernet LAN與ATM共存的結構。因此,研究 Ethernet的基本工作原理、優點與缺點,討論高速局域網絡發展的趨勢與特點,對我們學習和掌握局域網應用技術是十分重要的。

　　(1) 請用Ethernet發送與接收流程框圖說明CSMA/CD介質訪問控制方法的基本工作原理。(15分)

　　(2) 為什么說CSMA/CD屬于共享介質、隨機爭用型的介質訪問控制方法?這種方法主要缺點是什么? (5分)

　　(3) 你認為Fast Ethernet與ATM、Switching LAN是從哪兩個方面改進了傳統的Ethernet?它們各有什么優缺點? (10分)

　　論述題 2

　　進程通信就是進程之間進行信息交換。系統中各進程異步執行,但有些進程之間必須保持一定的聯系,以便協調一致地完成指定任務。這種聯系就是通過交換一定數量的信息來實現的。

　　消息緩沖通信技術是一種高級通信機制,由Hansen首先提出。其基本思想是:根據"生產者-消費者關系"原理,利用公共消息緩沖區實現進程之間的信息交換。

　　(1) 試敘述高級通信機制與低級通信機制P、V原語操作的主要區別。(5分)

　　(2) 試敘述解釋消息緩沖通信技術的基本原理。 (10分)

　　(3) 消息緩沖通信機制中提供發送消息原語。Send(receiver,a)和接收消息原語Receive(a)。調用參數a分別表示發送消息的內存區首地址或接收進程的內存消息區首地址。試設計相應的數據結構,并用P、V操作原語實現Send和Receive原語。 (15分)

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