(51) 在OSI參考模型中,同等層相互交換信息的實體構成了____。
    A) 相鄰實體 B) 對等實體 C) 傳輸實體 D) 通信實體
    (52) 在OSI參考模型中,兩個(N)層實體之間交換的數(shù)據(jù)單元稱之為(N)協(xié)議數(shù)據(jù)單元,記做(N)PDU。(N)PDU是由兩部分組成:(N)PCI與 ____。
    A) (N+1)IDU B) (N+1)SDU C) (N)SDU D) (N)IDU
    (53) 一個數(shù)據(jù)源產生8bit的ASCII字符(含1bit校驗位),通過一條64Kbps的線路進行數(shù)據(jù)傳輸。指出在以下數(shù)據(jù)傳輸方式中,哪一種方式的有效數(shù)據(jù)傳輸速率可以達到? ____。(2分)
    A) 采用面向字符型傳輸協(xié)議,每個數(shù)據(jù)幀包括24B的控制字段與128B的信息字段
    B) 除信息字段長度為256B外,其它條件同A)
    C) 采用面向比特型傳輸協(xié)議,每個數(shù)據(jù)幀包括12B的控制字段與64B的信息字段
    D) 除信息字段長度為128B外,其它條件同C)
    (54) 在面向比特型數(shù)據(jù)鏈路層協(xié)議HDLC中,幀格式中的哪個域既可以用于流量控制,又可以實現(xiàn)對發(fā)送幀的捎帶確認?____。（2分）
    A) 無編號幀的M域 B) 信息幀的N(S)域
    C) 監(jiān)控幀的S域 D) 信息幀的N(R)、N(S)域
    (55) IEEE802.5標準規(guī)定令牌環(huán)網(wǎng)采用 ____。
    A) 多令牌協(xié)議
    B) 單令牌協(xié)議
    C) 隨機訪問協(xié)議
    D) HDLC協(xié)議
    (56) 在局域網(wǎng)中,以下哪種傳輸介質既可以用于物理層10BASE-T協(xié)議,又可以適用于100BASE-T協(xié)議? ____。
    A) 同軸電纜 B) 3類非屏蔽雙絞線
    C) 5類非屏蔽雙絞線 D) 光纖電纜
    (57) 如果兩個局域網(wǎng)LAN A與LAN B互連,它們的傳輸層協(xié)議不同,而其它層協(xié)議均相同, LAN A與LAN B的互連設備應該選擇____。
    A) repeater B) bridge C) router D) gateway
    (58) CCITT推薦的用于多個X.25網(wǎng)絡互連的協(xié)議為____。
    A) X.400 B) X.75 C) X.121 D) X.21
    (59) 城市地區(qū)網(wǎng)(MAN)主要使用的技術是交換多兆位數(shù)據(jù)服務SMDS、分布隊列雙總線DQDB和____。
    A) FDDI B) CSMA/CD C) Token Bus D) Token Ring
    (60) 在計算機集成制造系統(tǒng)(CIMS)中,存在著辦 公自動化(OA)與生產過程控制(MC)兩種環(huán)境,它們對網(wǎng)絡通信的要求也不相同。在CIMS環(huán)境中,根據(jù)MAP/協(xié)議選擇局域網(wǎng)協(xié)議標準時，應采用以下哪種方案? ____。(2分)
    A) 全部采用802.3協(xié)議標準
    B) OA采用802.3協(xié)議標準,MC采用802.4協(xié)議標準
    C) OA采用802.3協(xié)議標準,MC采用802.5協(xié)議標準
    D) 全部采用HDLC協(xié)議標準
    (61) An instrucion that uses indirect addressing must contain an address of memory where____．
    A) data is stored B) another address is stored
    C) a page fault is addressed D) a pepeline stall will be executed
    (62) Let R be a binary relation on a set S such that for each x,y,z∈S, if xRy and xRz then y =z. Which of the following must be true? ____．(2分)
    A) R is anti-symmetric B) R is transitive
    C) R is an equivalence relation D) R is a function
    (63) If p and q are Boolean variables, which of the following formulas is (are) tautological?____．
    Ⅰ. (┐p→q)↔ (p∨q)
    Ⅱ. ((p→q))∧(q→r))→(p→r))
    A) none B) Ⅰ only C) Ⅱ only D) Ⅰ and Ⅱ
    (64) Which of the following statements is (are) true? ____．
    Ⅰ. The number of cyclic subgroups of the additive group of integers is infinite.
    Ⅱ. The number of cyclic subgroups of the additive group of real numbers is infinite.
    A)&nb sp;Neither B) Ⅰ only C) Ⅱ only D) Ⅰ and Ⅱ
    Questions 65- 66 refer to the space requirements of different methods of storing graphs. The choices for these questions are combinations of the following statements.
    Ⅰ. The space required depends on the number of vertices.
    Ⅱ. The space required depends on the number of edges.
    (65) When the adjacency matrix method is used to store a graph, which of the statements is (are) true? ____．
    A) None B) Ⅰ only C) Ⅱ only D) Ⅰ and Ⅱ
    (66) When the adjacency list method is used to store a graph, which of the statements is (are) true?____．
    A) None B) Ⅰ only C) Ⅱ only D) Ⅰ and Ⅱ
    Questions 67-68 are based on the following information,
    A hash table with hash function
    h1(k)=k mod 13
    is shown below.
    0 1 2 3 4 5 6 7 8 9 10 11 12
    35 33 48 25
    Collision is resolved using the hash function h2(k)=(k mod 11)+1.
    (67) How many key comparisons occur in searching for key 35 in the given hash table?____． (2分)
    A) 0 　B) 1 　C) 2 　D) 3
    (68)& If a new key 67 is inserted into the given hash table, what will be its address?____． (2分)
    A) 3 B) 4 C) 5 D) 6
    (69) Suppose the contents of the DOS IF1.BAT file on the hard disk is as follows.
    @ECHO OFF
    MEM>FILE1
    SORTFILE2
    DEL FILE1
    @DATE
    @TIME
    IF EXIST %1 ECHO % IF FOUND
    If all of the commands are successfully executed after IF1 FILE1 is
     typed, then the screen displays?____．
    A) None B) Date and time C) FILE1 IS FOUND D) FILE2 IS FOUND
    (70) If the files in the current directory are
    aac, abc, acb,acc, aca, ao, al, a2, ab, ac, aa,
    and the command ls a?[bc] is executed, how many files will be listed?____． (2分)
    A) 3 B) 4 C) 5 D) 6
    (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(wǎng)是當前計算機網(wǎng)絡研究與應用的一個熱點,而符合IEEE 802.3標準的傳統(tǒng)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(wǎng)絡應用的發(fā)展,以及大型信息系統(tǒng)與多媒體技術的應用,人們對局域網(wǎng)性能提出了越來越高的要求,出現(xiàn)了符合 100BASE-T標準的Fast Ethernet、交換局域網(wǎng)Switching LAN與ATM等高速局域網(wǎng)產品。盡管高速局域網(wǎng)技術發(fā)展十分迅速,但是Ethernet仍然會被廣泛地使用。今后的網(wǎng)絡應該是傳統(tǒng)Ethernet、FastEthernet LAN與ATM共存的結構。因此,研究 Ethernet的基本工作原理、優(yōu)點與缺點,討論高速局域網(wǎng)絡發(fā)展的趨勢與特點,對我們學習和掌握局域網(wǎng)應用技術是十分重要的。
    (1) 請用Ethernet發(fā)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(tǒng)的Ethernet?它們各有什么優(yōu)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(tǒng)中各進程異步執(zhí)行,但有些進程之間必須保持一定的聯(lián)系,以便協(xié)調一致地完成指定任務。這種聯(lián)系就是通過交換一定數(shù)量的信息來實現(xiàn)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(jù)"生產者－消費者關系"原理,利用公共消息緩沖區(qū)實現(xiàn)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(qū)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(fā)送消息原語。Send(receiver,a)和接收消息原語Receive(a)。調用參數(shù)a分別表示發(fā)送消息的內存區(qū)首地址或接收進程的內存消息區(qū)首地址。試設計相應的數(shù)據(jù)結構,并用P、V操作原語實現(xiàn)Send和Receive原語。 (15分)