And view layers data layer manages stored data

CIS312 Final Exam Study Guide Winter 2014
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Q1 – 7 7 of 34
Most current speech­recognition systems are _speaker dependent___, which means they must be “trained” to recognize the sounds of human speakers.

A(n) _laser printer___ operates with an electrical charge and the attraction of ink to this charge.

Inkjet and laser printers use pixelsas the fundamental output unit.

Pointing devices can be used to enter drawings into a computer system or control the position of a(n) cursor (pointer)____ on a display device.

A digital-to-analog converter (DAC)____ performs a reverse transformation, accepting a stream of bits representing sound samples and generating a continuous electrical signal that can be amplified and routed to a speaker.

A(n) analog-to-digital converter (ADC) ____ accepts a continuous electrical signal representing sound (such as microphone input), samples it at regular intervals, and outputs a stream of bits representing the samples. The process of converting analog sound waves to digital representation is called _sampling___.

T/F A printed character must exactly match a specific pixel map to be recognizable.

T/F Decades ago, printers adopted 1/32 of an inch as a standard pixel size.

CIS312 Final Exam Study Guide Winter 2014
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T/F On paper, pixel size corresponds to the smallest drop of ink that can be placed accurately on the page. T/F For video display, a pixel displays no light or light of a specific color and intensity.

Q8 – 13 6 of 36
T/F Messages can be loosely categorized into two types—data messages and command messages.

T/F Command messages can be used to transmit information about data messages, such as format, content, length, and other information the receiver needs to interpret the data message correctly.

T/F Phase is a wave characteristic that’s fundamentally the same as amplitude or frequency.

In a single communication channel a signal____ wire carries data.

In a single communication channel a return____ wire completes an electrical circuit between sending and receiving devices.

crosstalk,____ is noise added to the signal in the wire from EMI generated by adjacent wires.

Most local phone service is based on a channel­sharing strategy called circuit switching ____.

Multilevel coding____ is a technique for embedding multiple bit values in a single wave characteristic, such as frequency or amplitude.

Frequency modulation is also called frequency­shift keying (FSK) ____.

CIS312 Final Exam Study Guide Winter 2014
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A(n) ____ sends digital signals by modulating a carrier wave to embed bits in one or more analog wave characteristics.

As bit transmission speed is increased, the duration of each bit in the signal, known as the ____, decreases.

____ is based on the 802.3z standard and the 802.3ab standard.

At the sending node, the ____ layer’s role is to translate IP datagrams into a format that can be transported and forwarded over a specific physical network.

T/F Mesh topology is practical for all but very small networks.

T/F In a physical delivery system, the central nodes are transfer points located at or near the junction of major roadways or air routes.

T/F The OSI model predates the TCP/IP model by almost a decade.

T/F Star topologies now dominate physical network topology for wired networks.

VoIP equipment and software can be loosely divided into two groups: end nodes and ____.

The oldest and most widely used VoIP protocol suite is ____.

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T/F Software has surpassed hardware to become the most costly component of most information systems.

T/F Reduced productivity, dissatisfied customers, and poor managerial decisions are just a few indirect costs of software that doesn’t address users’ needs completely or correctly.

T/F C++ was the first commercial OOP language.

T/F With scripting languages, programmers can assemble application software rapidly by “gluing” together the capabilities of many other programs.

A ____ is a nonprocedural language suitable for developing software that mimics human intelligence.

A ____ uses mnemonics to represent instructions, variables, and labels and has a degree of instruction explosion higher than 1:1.

The one­to­many (1:N) relationship between later­generation programming statements and the CPU actions implementing them is called ____.

Today, the term ____ is often used to describe a mnemonic representing a data item’s memory address. A ____ defines the name and data type of program variables.

In virtual memory management, a ____ is a small fixed­size portion of a program, normally between 1 and 4 KB.

Each memory page in virtual memory management is called a ____.

A ____ can execute instructions to process a single transaction, retrieve and store data from an I/O device, or

retrieve and analyze one set of process variables.

The process of determining the physical memory address that corresponds to a memory reference is called ____.

T/F Data values and instructions generally occupy multiple bytes of storage.

T/F A blocked thread is waiting for an event to occur, such as allocation of a requested resource or correction of an error condition.

T/F In explicit priority scheduling, the scheduler always dispatches the ready thread that has been waiting the longest.

The ____ is the OS portion that manages resources and interacts directly with computer hardware.

The resources consumed by resource allocation procedures are sometimes referred to as ____.

T/F Multitasking operating systems are not the norm for general­purpose computers.

Q32 – 37 6 of 36
T/F Allocation units can be smaller than the unit of data transfer.

Each record in a data file is composed of multiple ____.

In a ____, directories can contain other directories, but a directory can’t be contained in more than one parent.

T/F Users and applications view secondary storage logically as a collection of files organized in directories and storage volumes.

T/F The logical file structure is dependent on the physical device on which it’s stored.

In UNIX, the ____ privilege allows a user or process to alter a file’s contents or delete it altogether.

The ____ contains a sequential set of file records, one for each file in the volume.

A ____ is a collection of data items, or fields, that an application program accesses as a single unit.

The directory that’s currently being accessed is called the ____ directory
A ____ is a data structure that records which allocation units are free and which belong to files.

describes any architecture in which software running on a CPU accesses secondary storage devices in the same computer.

The most common example of multiple RAID levels layered to combine their best features is ____.

____ is a collection of resources that can be accessed over the Internet by standard protocols, such as Hypertext Transfer Protocol (HTTP).

A(n) ____ describes rights granted or denied to users, groups, and computers for accessing resources in Active Directory.

copies.

In an LDAP directory, a(n) ____ defines the attributes common to all member objects.

With ____, a resource user asks for a resource, and if it isn’t found in the local resource registry, the resource locator searches for it in external locations.

A ____ server maintains a registry of names and corresponding IP addresses for each node on the local network.

Web resources are identified by a unique ____.

Under ____, e­mail messages are held on the server temporarily, downloaded to the client when a connection is established, and deleted from the server as soon as the download is finished.

T/F As OSs have evolved, they have incorporated less middleware functions.

T/F In large networks, responsibility for maintaining directory content and answering queries is centralized to a few individuals who manage the network.

CIS312 Final Exam Study Guide Winter 2014 8
T/F Servers can be offline or idle except when needed to access client resources.

T/F A server manages system resources and provides access to these resources through a well­defined communication interface.

Antivirus software uses data files, sometimes called “____,” containing information about known viruses. The simplest firewall type is a(n) ____ firewall, which examines each packet and matches header content to a list of allowed or denied packet types.

A ____ is stored in a stand­alone executable program, is usually sent as an e­mail attachment and runs automatically when the attachment is opened.

____ is the process of determining whether an authenticated user or process has enough rights to access a resource.

T/F Operating systems now cooperate with one another to perform authentication and authorization.

T/F Computer performance is measured in terms of application tasks that can be performed in a given time frame.

T/F The costs of technology are usually high for developers and early adopters but then decrease slowly after introduction.

CIS312 Computer Architecture
Chapters 11 – 13 Review Questions
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1. Describe the functions of the kernel, service, and command layers of an OS. The kernel manages hardware resources and interacts directly with hardware. It includes a resource allocation layer and interface programs called device drivers for each hardware device. The service layer is an interface to components that provide functions called from applications, ranging from file and folder manipulation to accessing I/O devices, starting and stopping programs, allocating memory, and creating, moving, and resizing GUI windows. The command layer provides a user interface to the OS for managing hardware and software resources.

2. What’s the difference between a real resource and a virtual resource?

4. What characteristics or capabilities differentiate a bare-metal hypervisor from a virtualization environment?

A bare-metal hypervisor is installed directly on hardware, and a virtualization environment runs in another OS, such as Windows or Linux. Bare-metal hypervisors are more efficient and can provide more resources to virtual machines; they’re intended mainly for server consolidation. Virtualization environments are targeted toward desktop OSs and enable a single desktop computer to run multiple OSs for the purposes of software testing or running PC applications on a Mac, for example.

A thread moves from the blocked to ready state when a requested resource is made available or when an error condition has been corrected. In either case, the scheduler makes the state change in response to interrupt processing being completed.

6. What is a process control block, and what is it used for?

Threads share all resources allocated to their parent processes with other threads in the same process, including primary storage, files, and I/O devices.

8. Briefly describe the most common methods for making priority-based scheduling decisions.

Virtual memory management uses a portion of secondary storage to expand primary storage’s capacity. Programs and memory are divided into portions called pages, and each memory page is called a page frame. During program execution, one or more pages are allocated to page frames, and the rest are held in secondary storage. As pages in secondary storage are needed for current processing, the OS copies them into page frames. If necessary, pages currently in memory are written to secondary storage to make room for pages being loaded.

Each memory reference is checked to see whether the page it refers to is currently in memory. A reference to a page held in memory is called a page hit, and a reference to a page held in secondary storage is called a page fault. The OS maintains page tables to store information about page locations, allocated page frames, status of pages, and secondary storage space.

Absolute addressing means that references to memory in software correspond to physical memory locations. With indirect addressing, the OS calculates and stores the process offset in a register when the program is first loaded into memory. During program execution, the CPU automatically adds the process offset to all memory references to convert them into physical memory locations.

13. What are the costs and benefits of indirect addressing?

The command layer or application program provides command-layer functions and utility programs for users to manage files, directories, and secondary storage devices.

The file control layer is the service-layer interface to the file system. It processes service calls from the command layer or application program and issues commands to the storage I/O control layer to interact with hardware. It also maintains the directory and storage

A file’s logical structure is composed of records and fields organized so that access by a program is as easy as possible. A file’s physical structure depends on the method of physical storage allocation and the physical characteristics of devices containing the file.

The two rarely match, so translation between them is necessary. Application programs are simplified because of their lack of interaction with the physical file structure. They need no knowledge of storage allocation issues and no programming that depends on them.

An allocation unit is the smallest number of secondary storage bytes that can be allocated to a file. Smaller allocation units result in more efficient use of storage space because little capacity is wasted. However, they increase the number of allocations units per device or medium, which increases the size of storage allocation data structures and the time needed for storage allocation procedures.

18. Describe the use of buffers in file I/O operations. When are buffers allocated? When are they
released?

In a graph structure, files and subdirectories can be contained in multiple directories, and directory links (or shortcuts in Windows) can form a cycle to allow file sharing. However,

links require special processing to avoid multiple listings and recursive loops in programs that list a directory’s contents and all its subdirectories.

File access rights include read (viewing a file’s contents), write (altering file contents or deleting a file), and execute (run an executable file). Rights can be denied to all but the file owner, extended to other members of a group, extended to all users, and even revoked for the file owner (to prevent accidental deletion, for example).

22. What is transaction logging or journaling? Describe the performance penalty it imposes on
file update operations.

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Storing parity data reduces a disk array’s usable capacity. Using more disks would decrease the portion of space used for parity bits but with a slight increase in the probability of data loss in the event of multiple disk failures.

Multiple RAID levels can be layered to combine their best features. For example, RAID 10 mirrors each disk (RAID 1) and then stripes data (RAID 0) across multiple mirrored pairs.

25. Describe client/server, three-layer, and n-layer architecture. What are the differences between a client and a server? What is the function of each layer in a three-layer application?

Why might more than three layers be used?

26. What is middleware?

Middleware is system software that “glues” together parts of a client/server or multitier application. It includes software such as Web servers that support embedded client-side CIS312 Computer Architecture
Chapters 11 – 13 Review Questions
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programs, database servers that support stored procedures, and network OSs that share files among clients on multiple computers.

Resource access consists of two layers: the resource locator and service provider. The resource locator maintains a local resource registry containing the names and locations of known resources and services. Static connections to resources remain unchanged after being configured by a user or system administrator. When resources are added, moved, renamed, or deleted, all users’ resource registries must be updated to reflect the changes. Dynamic connections are created as needed and discarded when they’re no longer being used.

With this type of connection, a resource user asks for a resource, and if it isn’t found in the local resource registry, the resource locator searches for it in external resource registries.

P2P protocols include sockets, named pipes, and RPC. Sockets enable cooperating processes to communicate by using unique port numbers on Internet hosts. Named pipes have directory entries in the file system that enable processes executing on different machines to exchange data. RPC enables a process on one machine to call a process on another machine, passing parameters in both directions. Sockets are used in both named pipes and RPC.

The advantage of using these protocols is that they enable processes to communicate synchronously across a network. However, data representation can vary across CPUs and sometimes across operating systems. If processes execute on machines with different data representation formats, data conversion is necessary.

Protocol—An optional header specifying the resource access protocol (http:// is the default value)

Host—The IP address or registered name of an Internet host computer or devicePort—An optional port number that, together with an IP address, specifies a socket (if omitted, a standard port number for the protocol is assumed)
Resource—The complete pathname to a resource on the host (if omitted, the host can return a default resource if configured correctly)
33. Describe at least five standard Internet and Web protocols.

Simple Mail Transfer Protocol (SMTP)—Defines how text messages are forwarded and routed between Internet hosts.

Multipurpose Internet Mail Extensions (MIME)—Enables including nontext files in e-mail messages.

A component is a standardized, interchangeable software module that’s executable and has a unique identifier and a well-known interface. Component-based design and development have only recently become the norm in software development because the standards and infrastructure supporting it are newer.

36. Describe the COM+ and CORBA standards for component infrastructure and communication. Which standard would you choose to support a new large-scale information
system? Why?

Directory services are middleware and provide a database of information about distributed resources and services and a means to access and search this database. Network directories typically store information about registered users and their access permissions, shared hardware resources, shared files, computer systems, and specialized hardware devices (network storage appliances, for example).

LDAP is a widely used standard for directory services. Each shareable resource and user is stored as an object, and each object is an instance of an objectclass, which defines the attributes common to all member objects. Objects can be organized into hierarchical structures with standard container objects, such as country, organization, and organizational unit.

The first step in locating a resource on an Internet-connected remote computer is to determine its IP address. DNS defines the process by which a client determines the IP address corresponding to a DNS name, such as www.microsoft.com. After the IP address has been determined, a client can contact the remote computer directly to access remote resources and services.

It’s unlikely that DNS could function with a centralized directory server architecture

Few cloud computing standards exist, which makes cloud vendor services generally incompatible with one another, and this incompatibility makes switching from one vendor to another more difficult. This difficulty is lowest with IaaS and highest with SaaS. Security is a bigger problem with cloud computing models because more potentially dangerous or sensitive information traverses public networks. When software and data are stored on a vendor’s systems, legal ownership must be specified as part of the service contract.

Chapter 14
CIS312 Computer Architecture
Chapter 14 Review Questions
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1. What is infrastructure? In what ways do hardware and system software qualify as infrastructure?

Standardization usually implies simpler management and minimal costs of providing service. It also ensures lower cost and fewer problems when upgrading or integrating systems. However, standardization tends to stifle innovation and shortchange users who demand services at the cutting edge of technology.

4. What is a request for proposal (RFP)? How are responses to an RFP evaluated?

There’s no way of precisely determining the hardware resources needed to run the program.

6. What is a monitor? List types of monitors and the information they provide.

8. What password-protection measures are normally implemented by system administrators, operating systems, and security services?

Password-protection measures include:
Restrictions on minimum length, maximum age, and minimum
complexity requirements
Encryption of passwords stored in files or transmitted over a
network
Lockout procedures that limit password-guessing attacks
9. Describe the pros and cons of enabling auditing of resource accesses.

hard-to-find location
Performs malicious actions on the infected computer
Replicates and spreads itself by using services of the infected
computer
CIS312 Computer Architecture
Chapter 14 Review Questions
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Viruses are best prevented by installing and enabling antivirus software, including automatic updates to virus data files.

11. Why is it important to install OS and application software updates in a timely manner? How can users and system administrators ensure that they’re installed in a timely manner?

An application firewall prevents direct access to a server by receiving incoming packets for that server and forwarding only packets that meet stated criteria. Stateful firewalls perform a similar function as application firewalls, but they use more sophisticated packet analysis methods that look for and track specific patterns of activity between client and server.

Regardless of the firewall type, security is enhanced by preventing a computer system from receiving or processing malicious packets.