计算机导论期末复习资料.doc

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1、1 Numbers ConvertionIn this section, you will convert numbers among binary, decimal and hexadecimal representations.a. Complete the following chart by converting the numbers given in one of the notations to the other two. Show calculations.BinaryDecimalHexadecimal1011 0111183B71100 1000200C8111115F2

2、43F32190xDB6940x2B6b. What is the minimum number of bits that can be used to represent the decimal number 1013? (Hint: convert 1013 to binary.)10c. What is a purpose of using hexadecimal notation?Answer:Using hexadecimal notation is to express binary values more concisely. Because when we express a

3、value, it will take more digits in binary notation than in decimal notation. d. What is ASCII code? Answer:ASCII code is American Standard Code for Information Interchange. It is the built-in binary code for representing characters in all computers except IBM mainframes and realizes data transmissio

4、n standardization in vary computer systems. In modern time most mainframe and all PC use it . ASCII code includes two set : Standard ASCII code with 128 characters and Extended ASCII code with 128 characters appended.2. Computer Speed a. One Hz is one _ per _. One Hz is one cycle per second.b. Defin

5、e IPS. IPS is instructions per second which is a rating of how many instructions can be executed by a processor in a given second.c. Answer the following questions on the relationship of Hz to IPS. i. Which is a better determiner of speed: MHz or IPS?IPS is a better determiner of computer performanc

6、e.ii. Does a high Hz equal a high IPS, and can they be inversely proportional? Explain.A high Hz can indicate that the IPS is high, but they are not directly proportional, but can never be inversely proportionaliii. How is it possible for a machine with a lower clock speed (Hz) to have a higher IPS

7、than a machine with a higher clock speed? An instruction can take a variable amount of cycles or partial cycles. Thus, a computer can execute instructions more quickly than another computer because of this.d. What is the relationship between the system clock and Hz? The system clock sends out pulses

8、 at regular intervals to set up the timings for all timed system activities, such as determining the Hz of a processor.3. BIOS and CMOS a. Explain the function of the BIOS ROM in the boot process. The BIOS ROM is a permanent storage device that contains the startup instructions for the computer.b. D

9、efine flashing, with respect to BIOS ROM. Flashing is the process of rewriting an EEPROM. This process allows the BIOS to be updated without changing ROM chips.c. Explain the function of the CMOS in the boot process. The CMOS contains the configurable system information that the BIOS reads during st

10、artup.d. What is the advantage of having an unchangeable ROM and a changeable CMOS during the boot process? By having an unchangeable BIOS, a default startup configuration is always possible. Since, however, startup configurations may differ from machine to machine, the changeable CMOS allows users

11、to specify exactly how the boot will occur on their machines, possibly changing the startup from the default.e. Consider that the CMOS has lost power. i. What happens to the data that was stored in the CMOS? The CMOS is volatile and will lose all data contained in it if it loses powerii. How does th

12、e CMOS losing power affect the boot process? When CMOS power fails it no longer contains configuration data, and therefore when a machine is booted, it will use the default settings contained in the BIOS.f. List two ways to change the information in the CMOS. Windows Plug-N-Play, as an example.BIOS

13、setup and configuration utility, as an example.4. Layers a. The layers of software have already been list down. Fill the correct number of layers in table from lowest to highest. (1) User Interface(2) Run-Time Libraries(3) User-Written Scripts or Macros(4) Application Programming Interface(5) Kernel

14、(6) BIOS(7) Application(8) Operating System(9) Device Drivers317248596b. Describe encapsulation with respect to the layers of software. Encapsulation means that a layer is closed off from other layers, achieving only it owns ends without knowing much about the other layers.c. Describe abstraction wi

15、th respect to the layers of software. Abstraction is the means of sharing data and communicating that is established between various layers of software.d. What advantage do encapsulation and abstraction give to software developers? Encapsulation and abstraction allow developers to provide limited me

16、ans of accessing data to their layer, and that they only must support limited influx of data from other layers abstraction. The layer can be comprised of code that other layers need not be involved in.5. Networks a. What is a LAN? Local Area Network. A network smaller than a WAN; typically a compute

17、r network covering a local area, like a home, office, or group of buildings. b. What is a WAN? Wide Area Network. A computer network larger than a LAN; typically a network that spans buildings, cities, or countries. The internet is a WAN.c. What is a thin client? A network application in which the c

18、lient does very little processing and the network server does most of the work.d. What is a thick client? A network application in which the client does relatively significant processing, and the network server does more simple tasks.e. What are the implications of thin and thick clients for a serve

19、r? Thin clients make larger processing demands on a server, and so the server can support fewer thin clients.f. What is a domain name? A fully-qualified domain name contains a machine, domain, and top-level domain designation. From this common name structure an IP address can be referenced and the m

20、achine connected to.g. Explain what is indicated by each part of . www is the actual name of the machine (server) from which the data is being requested. icarnegie is the domain in which the machine www resides. This domain may contain many is referred to as a top-level domain. Many domains are hou

21、sed under the umbrella of org. This is one of the many top-level domains and allows greater variation in naming.h. List five non-country, top-level domains. .com, .mil, .gov, .int, .net 6. Data Integrity a. In the context of Java applets, what is a sandbox, and how does it protect computer informati

22、on? A sandbox is a secure location to run Java applets and ActiveX controls.A sandbox protects the data on your computer from outsiders, who can use Java applets and ActiveX controls to access secure or private information.b. What is a digital certificate, and how does it protect computer informatio

23、n? A digital certificate is a method of authentication for identifying the author of a given software program.A digital certificate allows the user to ensure that the software being downloaded is from a reputable source before running it.c. What is a firewall, and how does it protect computer inform

24、ation? A firewall is a set of rules that govern communications over a network. A firewall basically denies communications unless a rule allows them to occur.A firewall protects a computer system, by always denying network communications requests that the user has not predefined as permissible.d. In

25、the context of a Web browser, what is a cookie, and how might it not protect computer information? A cookie is a text file that contains information about visiting Web sites.Cookies are thought not to protect a persons privacy by allowing Web sites to read them and determine usage patterns of Web si

26、tes and pages visited.7. Dictionary-based Compression Consider the message below:exam1, exam2, and exam3 are required exams.a. How many bytes does the message contain (each character is 1 byte including spaces)? b. Create a compression dictionary and calculate its size in bytes. c. What is the compr

27、essed message? d. How many bytes did the entire compression use? Show calculations. e. Is dictionary-based compression a lossy compression? Explain.43 bytes$exam 5 bytes$1, $2, and $3 are required $s.31 bytes (message) + 5 bytes (dictionary) = 36 bytes.No, dictionary compression is not a lossy compr

28、ession because data is being replaced with shortened representations and not lost.8Port Identification Consider the following devices:Mouse Printer Keyboard Modem Speaker Digital camera Ethernet jack MonitorFor the following questions, indicate which device(s) should be plugged in which port(s) A-H

29、shown in the diagram below.a. What device(s) can be plugged into port A? i. What is the name of this port? ii. Is this a serial port or parallel port? b. What device(s) can be plugged into port B? i. What is the name of this port? ii. Is this a serial port or parallel port? c. What device(s) can be

30、plugged into port C? i. What is the name of this port? ii. Is this a serial port or parallel port? d. What device(s) can be plugged into port D? i. What is the name of this port? ii. Is this a serial port or parallel port? e. What device(s) can be plugged into port E? f. What device(s) can be plugge

31、d into port F? g. What device(s) can be plugged into port G? h. What device(s) can be plugged into port H?Keyboard or mouse.PS/2 portSerialDigital camera, keyboard, mouse, printer, external storage, network adapter, etc.USB portSerialModem or mouseDB-9 (serial) portSerialPrinterParallel (printer) po

32、rtParallelSpeakerMonitorPhone lineEthernet network9Computer ConfigurationLet us assume that you are purchasing a new computer for a specific usage. You need to choose a computer from various available configurations. Listed below are four different usage cases of a computer (a-d). For each usage cas

33、e, identify components of the computer configuration that are most important to consider. Explain your answers. Components to be considered include (but are not limited to): Monitor size/resolution Graphics card/video card Storage devices (e.g. DVD-ROM) Memory (RAM, cache, and hard disk) Disk contro

34、ller interfaces (ATA, EIDE) For example, if a computer were to be used for viewing movies, a DVD-ROM drive is needed since movies are available as CDs and now increasingly as DVDs. A large monitor (about 19”) that supports high resolutions and a video card will also be necessary to enjoy the movie.

35、a. Playing three-dimensional arcade games ？b. Server machine to store and retrieve huge volumes of data？a. Simultaneously running a number of programsTo run a number of programs simultaneously, a configuration with sufficient RAM must be selected so that the performance would not suffer because seve

36、ral large programs might be running concurrently.b. Running a speed-critical applicationFor a speed-critical application, a configuration with a fast processor is essential. In addition to a fast processor, a proper memory hierarchy is needed so as to take advantage of the fast processor. Also to be

37、 taken into account are L1 and L2 cache memories, as well as the amount of main memory. Typically, it is preferable to have L1 and L2 cache memories that use SRAM, and a main memory that uses SDRAM. c. Storing and retrieving huge volumes of dataTo store huge volumes of data, a hard disk with a huge

38、capacity is needed. If frequent retrieval of data is needed, then fast access times are needed. It would be advantageous if direct memory access were used to transfer data from the hard disk to the RAM without wasting processor time. Thus a hard disk drive with an Ultra ATA controller and DMA data t

39、ransfer would be preferred.d. Purchasing a basic configuration, to be upgraded later as neededTo have room for further upgrades and additions, it is essential to ensure that the computer to be purchased has sufficient expansion options. The numbers of free internal and external bays available are to

40、 be considered, as well as the number of built-in ports that are available. If the initial purchase only has a keyboard and mouse for input and a monitor for output, it is essential to ensure that ports are available for further additions such as printers, scanners, modems, external hard drive, etc.

41、10.Software Licenses I Define shrink-wrap license. II Define shareware license. III Define public-domain license.IV For each type of license listed in parts a, b, and c, give one example of a program distributed under that type of license.A licensing agreement that is printed on a software package t

42、hat is automatically agreed to when the user opens the software. While this is not always the case nowadays, the term mainly refers to software that is purchased before use.Shareware licenses grant the user permission to try the software before it is bought. Users need to send in a registration fee

43、if they wish to continue to use it.This type of license allows the user to modify, append to, and manipulate the software in any way. The software belongs to the people.Shrink-wrap: Microsoft Windows Me, as an example.Shareware: WinZip, as an example.Public Domain: Apache Web Server, as an example.1

44、1.Data Transfer a. What is the purpose of an NIC? b. What is the function of a hub? c. What is the function of a router? d. Describe how a website request given the URL is made from a home computer to the Internet once it reaches the DNS server? e. To ensure data transmitted is correct, even parity

45、bit protocol is used. Fill in the parity bits for the following data:Data Parity BitThe purpose of a Network Interface Card (NIC) is to connect the computer to a network, allowing the system to send and receive data over the network connection.A hub is used to connect machines in a star topology net

46、work. It sends data that it receives back to every port, so that the data is can be sent to the correct system.A router is a computer that maintains a table of ports and addresses, matching ports with one or many given addresses. A router sends packets that it receives only to the port that the pack

47、ets destination address matches, using the table to translate the address to the correct port.When the URL data reaches the DNS server, the DNS server looks into the database to find the destination IP address corresponding to the domain name of the host. After the IP address is determined, the data passes through the router, which decides the path to send the data to the destination IP address. The data packets may go through many routers before arriving at the addressed host.Data Parity Bit10011112.Computer S