Computer Class 12 GSEB Solutions Chapter 13 Other Useful Free Tools and Services

Students frequently turn to Computer Class 12 GSEB Solutions and GSEB Computer Textbook Solutions Class 12 Chapter 13 Other Useful Free Tools and Services for practice and self-assessment.

GSEB Computer Textbook Solutions Class 12 Chapter 13 Other Useful Free Tools and Services

Question 1.
Write a short note on a data compression.
Answer:

• A modern computer system has lakhs of files on them.
• Often one needs to transfer a large number of these files or an entire directory structure to another computer or storage device.
• When one wants to transfer files (containing data or programs or both) to another computer or storage device, the amount of data to be transferred or stored becomes a concern.
• Both computer networks and external storage devices are usually not as fast as internal components of a computer.
• Thus, transferring larger amount of data can take more time.
• If the Internet is used for such transfers, more time may be taken in the transfer due to slow Internet speed. Also, such transfers put load on the usually clogged Internet connection.
• Unless the user or organization has unlimited Internet plan, higher amount of data may result in higher cost as well.
• Similarly, if the files and directories are transferred to a storage device, the amount of the data to be transferred again becomes an issue because of the finite capacity of storage devices and the multiple uses that they are put through.
• Considering these issues, there is a need to reduce the amount of storage space occupied by computer files (and entire directory structures), whenever possible.
• From a convenience point of view, in many cases it is also desirable to have a single file to handle rather than a large bunch of files or a complex directory structure.
• Computer scientists have developed techniques to place a whole directory structure into a single file for convenience. Such a file is called an “archive”. They have also developed a number of techniques for reducing the storage requirements of computer files and directory structures.
• These techniques are called data compression. Data compression generally works by identifying repetition in the data and encoding the data in a way that reduces or eliminates such repetition.
• Some techniques also identify and eliminate less important information to conserve space. As an example, consider the children’s rhyme shown in figure.
• It certainly has a lot of repetition of words.
• We can take advantage of this and represent each word by a single digit or letter. At the beginning of our encoded file, one can have a table that tells which digit / letter represents which word (this information is needed to convert the file back in its original uncompressed form).
• Afterwards, one can use a single digit / letter to represent a word.
• Thus, lengthy words appear only one time and subsequently they are represented by a single character.
• The punctuation should be left as it is.
• Mark the beginning of the table with a ∧ (caret) symbol and end of the table with a $ symbol.
• The encoded file is also shown in the second half of the figure.

• While the size of the original file was 324 bytes, the size of the encoded file is just 226 bytes.
• This is because each word is used in its full form only once.
• Subsequently it is represented by a single character.
• The encoded file can be transformed into the original file at any time using the reverse process.
• The scheme described here is quite simple.
• Actual data compression programs use far more sophisticated algorithm based on information theory to achieve even greater reduction in size.
• Fortunately, Linux provides ready-made free and open source software for managing archive files.
• It is called Archive Manager.

Question 2.
Why do we need data compression tools ?
Answer:

• A modern computer system has lakhs of files on them.
• Often one needs to transfer a large number of these files or an entire directory structure to another computer or storage device.
• When one wants to transfer files (containing data or programs or both) to another computer or storage device, the amount of data to be transferred or stored becomes a concern.
• Both computer networks and external storage devices are usually not as fast as internal components of a computer.
• Thus, transferring larger amount of data can take more time.
• If the Internet is used for such transfers, more time may be taken in the transfer due to slow Internet speed. Also, such transfers put load on the usually clogged Internet connection.
• Unless the user or organization has unlimited Internet plan, higher amount of data may result in higher cost as well.
• Similarly, if the files and directories are transferred to a storage device, the amount of the data to be transferred again becomes an issue because of the finite capacity of storage devices and the multiple uses that they are put through.
• Considering these issues, there is a need to reduce the amount of storage space occupied by computer files (and entire directory structures), whenever possible.
• From a convenience point of view, in many cases it is also desirable to have a single file to handle rather than a large bunch of files or a complex directory structure.
• Computer scientists have developed techniques to place a whole directory structure into a single file for convenience. Such a file is called an “archive”. They have also developed a number of techniques for reducing the storage requirements of computer files and directory structures.
• These techniques are called data compression. Data compression generally works by identifying repetition in the data and encoding the data in a way that reduces or eliminates such repetition.
• Some techniques also identify and eliminate less important information to conserve space. As an example, consider the children’s rhyme shown in figure.
• It certainly has a lot of repetition of words.
• We can take advantage of this and represent each word by a single digit or letter. At the beginning of our encoded file, one can have a table that tells which digit / letter represents which word (this information is needed to convert the file back in its original uncompressed form).
• Afterwards, one can use a single digit / letter to represent a word.
• Thus, lengthy words appear only one time and subsequently they are represented by a single character.
• The punctuation should be left as it is.
• Mark the beginning of the table with a ∧ (caret) symbol and end of the table with a $ symbol.
• The encoded file is also shown in the second half of the figure.

• While the size of the original file was 324 bytes, the size of the encoded file is just 226 bytes.
• This is because each word is used in its full form only once.
• Subsequently it is represented by a single character.
• The encoded file can be transformed into the original file at any time using the reverse process.
• The scheme described here is quite simple.
• Actual data compression programs use far more sophisticated algorithm based on information theory to achieve even greater reduction in size.
• Fortunately, Linux provides ready-made free and open source software for managing archive files.
• It is called Archive Manager.

Question 3.
List main features of Archive Manager.
Answer:
Archive Manager

• Archive Manager as shown in figure permits the user to combine many files or an entire directory tree into a single file known as an archive.
• On Linux systems, tar (tape archiver) is the most common archive format.
• It also provides the facility of compressing file formats.
• The most common compressed file formats are the zip file format and the tar.gz file format.
• While the zip file format supports storing multiple files in a single zip file, on Unix / Linux systems the common practice is to combine the files into a single uncompressed file in the tar format and then compress the file in the zip format using gzip (GNU zip, an open source archiving program).
• Such a file commonly has the extension tar.gz and is called a “tar ball”.
• The tar ball is a very common format for distributing software or bundles of files on the Linux platform.
• The zip format is also used by different applications under different names.
• For example, the JAR files used in Java and the OpenOffice.org office suite file formats use zip compression.
• Archive Manager uses the extension part of the filename to identify the file format when opening an archive and to select the file format when creating a new archive.

•  Archive Manager can also be used to explore the contents of archives, to extract files from the archives, to add new files to the archive, to delete files from the archive and perform other such operations.
• There is no menu item to start the archive manager by default.
• One can double-click on an archive file in the Nautilus file browser to start the archive manager. A new archive can be created by right-clicking a file or directory and selecting the Compress… option from the context menu.
• This creates a new archive with that file or directory as its contents.
• This option is not available for files that are themselves archives.
• If one wishes, Archive Manager can be added to the Accessories sub menu of the Application menu.
• For this, right-click the Ubuntu icon in the upper left corner, select Edit Menu from the list, click on Accessories in the dialog box that opens and select the check box for Archive Manager and close the dialog box.
• When an archive is open in the Archive Manager, the view is similar to a directory open in the Nautilus file browser as can be seen in figure.
• The operations and keyboard shortcuts are also similar. Double-clicking a directory opens that directory and shows its contents.
• The Up and Back buttons in the toolbar can be used to go to the parent directory (if it exists in the archive) and the previous directory (if any) respectively.
• They are enabled only when applicable.
• Thus the Archive Manager helps us in creating and using archive files for backup for transfer via an external storage device, for transfer via network for saving disk space, etc.

Question 4.
Write the main features of the VLC media player.
Answer:
The VLC Media Player

• Ubuntu has many built-in tools to play multimedia content like audio, video, etc.
• However, another great open source tool called VLC (originally it was short form ofVideoLAN client) media player as shown in figure.
• It is also popular because of its versatility and features.

• Started as an academic project by the music- loving students of a university in Paris, it is now a community project available under multiple operating systems and has been downloaded over a billion times.
• One of the issues faced with multimedia content is that there are a variety of ways of converting multimedia information coming from hardware devices (audio / video streams) into computer data and then converting the computer data back into audio / video streams for playing on the hardware devices.
• This conversion (coding) and reverse conversion (decoding) is performed by a software component called codec (coder decoder).
• Each multimedia data format requires its own codec.
• The advantage of VLC is that it supports all the popular codecs and hence all the popular formats.
• It also supports all the major types of devices including web cameras, HD monitors, speakers of all types, microphones, headphones.
• VLC provides several options for playback of audio and video.
• It can convert multimedia files from one format to another.
• It can also stream (send) audio / video to and receive audio / video from another computer(s) over the network.
• After starting VLC from the Applications → Sound & Audio menu, one can open one or more files using the Media → Open File… menu item. An entire directory can be opened using the Media → Open Directory… option.
• If a directory is opened, VLC will actually open all media files in that directory playable by it.
• When one or more files are opened, they are added to the playlist.
• The playlist is a list of media files (tracks) to be played.
• One can play the media in the playlist in sequence, or in random order.
• Previous or next track can be selected.
• The playlist can also be saved to play the same tracks again later.
• The playlist can be opened using the View → Playlist option and saved using the Media → Save Playlist to File… option.
• VLC supports multiple file formats for playlist, but M3U is more common.
• At the bottom of the window, VLC displays a progress bar showing how much of the current track has been played and what is its total duration.
• By sliding the little slider on the bar, one can move back and forth in the current track.
• Below that, there is the play button (marked with a little right-pointing triangle). When the track is playing, the button turns into a pause button (with two parallel bars on it).
• If the playback is paused, the button reverts back to play mode.
• The middle button in the next three buttons is used to stop the playback completely, while the buttons with double arrows on the left and right allows jumping to the previous and next track respectively.
• The next button acts as a toggle between watching a video in a window against watching it in full screen mode.
• That means, every time the button is clicked, it switches from one of these states to the other.
• In full screen mode, even the controls like play / pause, stop is hidden. The controls can be displayed in a temporary floating window by moving the mouse cursor over the video.
• The next button is for displaying the playlist.
• These options are available in the menu also.
• While VLC has a lot of other functionalities as well, VLC can also be used to convert multimedia files from one format to another.
• For this select the Media → Convert / Save option from the menu.
• Using the Add button, select and add the file to be converted.
• Then from the list besides the Convert / Save button, select the Convert option.
• This will open another dialog box.
• Provide the destination file (in which the converted track will be saved). Also select appropriate file format (audio or video) from the drop down provided.
• Click on the Start button to start the process and the progress will be shown. Sometimes, one can get an error in the conversion process also.

Question 5.
List the applications of Google Maps.
Answer:
Google Maps.

• Google maps shown in figure is a free Internet-based service provided by Google, Inc.
• Google has, over a period of years, collected extensive map data for the whole earth through various means like satellite imagery, cars with cameras mounted on them, data purchased from other organizations and data provided by millions of individual users around the world.
• Google Maps allows anybody to edit the maps and identify landmarks, buildings, etc.
• It also allows users to upload photographs of the place and post reviews of the place.
• The service is also heavily used on mobile devices like smartphones and tablets.

• The service can be accessed from the web browser by opening the website http://www.google.co.in and selecting the Maps option from the top menu or directly entering the URL http:// maps.google.co.in.
• On mobile phones, the service may be accessed from the mobile phone’s web browser as well as from the Google Maps application.
• When accessed, the service first tries to know the current location of the user. On the PC, a rough idea of the user’s location can be obtained from the user’s Internet connection.
• On a mobile phone, the user’s location can be known with very high accuracy if the GPS (Global Positioning System) facility is used.
• This system finds a user’s location with an estimated error of only few meters using satellite signals.
• Google maps also allow the user to correct the location, if it is inaccurate. Then it shows a map of the current location.
• The map can be scrolled (pan) by dragging it in different directions or by clicking on the arrows in a circle on the left hand side.
• A vertical slider bar on the left allows us to zoom in and out on the map. Google maps can show the information of a place in different forms.
• The default view is map view, shown in figure By clicking on the Satellite button, the view can be switched to the satellite image as shown in figure.
• In this view, the images taken by satellites in the sky are shown.
• The images are clear enough to identify most familiar buildings and roads. The service also provides the facility of getting directions on how to reach from place A to place B.
• The two places may be two different cities or places within the same city.
• The service also provides a choice of routes where available. Figure shows an example.
• The service even provides turn-by-turn guidance while travelling if a mobile phone device is equipped with GPS receiver.
• On a highway or in a crowded city area, walking or driving, the service decides the route based on the current location and destination and guides us with on-screen as well as voice (spoken) instructions.

• There are several uses of the service. It can be used to search for a place and find its exact location.
• It can also be used to find directions to places unknown to us or in cities one is not familiar with.
• Government organizations and businesses use the service to provide people information on how to reach their offices.
• The service also has a facility using which anyone can display a map of any place on one’s website.
• Many organizations display such maps on their websites.
• Tourist information websites and Tourism departments of governments also make use of this service.
• It can also be used to display bus routes, current location of running trains, etc.
• The service also provides the facility of finding the nearest ATM Centre, bank, restaurant, bus stop or any other such essential place.

Question 6.
Explain the use of the Character Map program.
Answer:
Character Map

• The Character Map program shown in figure can be used to enter Unicode characters into any application.
• The script has to be selected from the left pane first and then double click characters to insert them into the Test to copy area below.
• Spaces and punctuation can be entered by the user from the keyboard directly into the area after clicking in it.
• Combining characters, like the long “II” (??????) in Gujarati can also be entered and combine with the corresponding constant appropriately.
• Brief details of the character currently selected with single-click or entered with double-click are shown in , the status line at the bottom, while more details on the character is available in the Character Details tab.
• After getting a substantial amount of content, the user can copy the content and past into an application.
• A Character Map is good solution if one has to type a few characters in another script occasionally.

Question 7.
Choose the most appropriate option from those given below:

1) Which of the following refers to a file that has an entire directory structure inside it ?
(A) apache
(B) archie
(C) archi
(D) archive
Answer:
(D) archive

2) What is the full form of tar ?
(A) tape archiver
(B) tech archiver
(C) test archiver
(D) tight archiver
Answer:
(A) tape archiver

3) For which types of archives is the password protection option available ?
(A) zip
(B) tar
(C) tar.gz
(D)both zip and tar.gz
Answer:
(D)both zip and tar.gz

4) Which of the following is a feature-rich media player ?
(A) VAC
(B) VEC
(C) VLC
(D)VNC
Answer:
(C) VLC

5) What is the full from of VLC ?
(A) Video LAN Client
(B) Video Line Coder
(C) Video Length Coder
(D) Video List Creater
Answer:
(A) Video LAN Client

6) Which technology gives our location with accuracy ?
(A) GRS
(B) GPRS
(C) GRPS
(D) GPS
Answer:
(D) GPS

7) Which program is used to enter Unicode characters into any application ?
(A) Character Display
(B) Character Insert
(C) Character Map
(D) Character Select
Answer:
(C) Character Map

8) Which command is used to quit from R ?
(A) quit()
(B) q()
(C) exit()
(D) close()
Answer:
(B) q()

9) Which function is used to create a bar graph in R ?
(A) bar()
(B) plot()
(C) bargraph()
(D) barplot()
Answer:
(D) barplot()

10) Which of the following are different variants of Rational Plan ?
(A) Single, Multi, Viewer
(B) Singular, Multiple
(C) View, Preview
(D) Server, Client
Answer:
(A) Single, Multi, Viewer

Computer Class 12 GSEB Notes Chapter 13 Other Useful Free Tools and Services

The R software

• R is a free software environment for statistical computing.
• It is a GNU project.
• It is widely used for statistical analysis.
• It has its own scripting language.
• It is a case-sensitive language.
• R has two work environments namely Command Line and Graphical.
• To use it in a GUI environment, it has to be installed with graphic editors like R Commander or RStudio from Ubuntu Software Center.
• To install R software on the machines, give the following command :
  sudo apt-get install r-base r-base-dev
• To invoke the R scripts from terminal window, open terminal and type on the command prompt.
• A welcome message along with R prompt will be displayed as shown in figure.

• Just like the Linux shell, R uses # as the comment , marker. Any text following #, up to the end of the line is treated as a comment.
• Number and string are the basic data types. Strings may be enclosed in single quotes or double quotes.
• Common operators and functions are available, just like other programming languages. Ordered lists of items (arrays or lists) are commonly used and are also referred to as vectors.
• Lists are created using the c function to combine several numbers into a single list.
• Most operators like +, -, *, /, and others work equally well on single number as well as on lists.
• However, when both operands of binary operators are lists, their lengths (number of elements in them) should ordinarily be same.
• Entering the name of a variable and pressing ENTER displays its value. An example of this concept is shown in figure.

• Here the symbol > shows the prompt of R.
• The statement > a ← 10 defines a variable ‘a’ and assigns it a value 10.
• The statement > a followed by Enter key press displays the value of a.
  Similarly the statement > b ← 20 defines a variable ‘b’ and assigns it a value 20.
• The statement > a*b followed by Enter key press multiplies the value of variable ‘a’ and ’b’ and displays the result on the prompt.
• Some common R commands include q() for quitting R, help() for accessing the on line help, demo() for viewing some demonstrations and help.startO to open the on line help in a browser.
• To get help on a particular function syntax help (function name) can be used.
• While quitting R, the software prompts whether the data(values of variables) has to be saved from the current session.
• If the user responds “yes” or “y”, the data will be saved in a file in the current directory and will be available in the next session of R starting from the same directory.
• The function ls() displays a list of all the variables defined as shown in figure.

• A series of consecutive numbers (range) may be generated using the syntax start: end.
• For example, 1 : 5 is same as c(l, 2, 3, 4, 5).
• R also provides basic statistical operations in quite straightforward forms.
• For example functions like min(list), max(list), mean(list) and median(list) can be used to find the minimum value, maximum value, mean and median for the list as shown in figure.

Plotting in R

• Assuming that a bar chart has to be plotted, representing faculty wise students in a university.
• Define the number of students as a list and the names of faculties as another list.
• Then use the function barplot with various arguments for drawing the plot as shown in figure.

• The first argument specifies the data list, while all other arguments have the form name=value.
• Use the arguments main, xlab, ylab, names.arg, ylim and border to specify the main title, X-axis label, Y-axis label, the values to be displayed for the bars, the range of values to be plotted on the Y-axis and border color respectively.
• Observe that for long commands, when Enter is pressed before the command is complete, R issues the + prompt until the command is completed.
• By default the graph does not have grid lines as can be seen in figure.

• Producing histograms is also not difficult.
• Suppose marks out of 100 in a particular subject for several students are used as the database.
• The histogram can be drawn using the code shown in figure and will look like the plot shown in the same figure.

RationalPlan

• People working in different areas like construction, engineering, services and consulting, business or software developmentusually work on aproject that is having constraints oftime, resource and budget.
• Any delay in completion of the project increases the cost of the project. At some point of time to manage this kind of project there is a need to prepare, maintain and follow a well-defined plan.
• Such a plan helps to complete the project as scheduled, on time and within budget.
• RationalPlan is one such open source software designed to assist project managers in preparing, maintaining and following a well-defined project plan.
• It assists the project managers throughout the life cycle of their projects.
• It comprises three different desktop products namely RationalPlan single, Multi and Viewer.
• RationalPlan Single allows the users to manage independent projects that do not have common resources and has no interrelations between different projects.
• It allows the manager to associate general project information like name, notes, links, assumptions, constraints or risks.
• It allows creating, editing and deleting calendars, building schedules.
• Once the resources are created, tasks can be assigned to them.
• It provides project tracking tools such as critical path, mark completion value for tasks, work and cost time phased information.
• A printable report can be generated as well as data can be imported from other project management tool or data can be exported into other formats.
• RationalPlan Multi allows the user to manage projects that share company resources across projects.
• It also manages interdependencies between projects.
• It includes all the features of RationalPlan Single Project.
• Further it calculates the resources data (work, cost, over allocation) considering their assignments in all projects.
• It allows links between tasks pertaining to different projects, analyzes all our projects data and creates a project Portfolio view.
• RationalPlan Viewer is an additional tool developed to share the project in its original file format (.xrp), but it can be used as well to open Microsoft Project files.
• It is useful to anybody who needs to check and overview the project’s evolution without making changes to the schedule and for resources to see their assignments.
• Though as of today, the support of RationalPlan on Ubuntu 10.04 has been removed, it is available for Ubuntu 12.04 and later versions.

Skype

• Today everyone has used various instant messaging services like Yahoo Messenger, Google Talk or Rediff Bol.
• They are used for real time chatting with text, audio and video facilities.
• Skype is one such software that allows the users to make calls over the Internet using computer systems.
• The Skype service allows users to communicate with peers using voice, video as well as text.
• Skype can be used to place phone call to recipients on the traditional telephone network also.
• The calls to landline telephones or mobile phones are charged via a debit based user account system while calls to other users within the Skype service are free of charge.
• It also provides additional features like file transfer and videoconferencing.
• The Skype software can be downloaded free of cost, though its source code is proprietary and not available for modification.
• To use Skype, a working sound input and output configuration is needed.
• Most modern computers today support both these features.
• In laptops they are inbuilt while on desktop, extensions like a headset, speaker and a web cam are used.
• Skype software can be installed from the Software Centre.
• To start Skype, choose Application → Internet→ Skype.
• If it is being opened for the first time, it will open an end User License Agreement window.
• The contents can be read and “I agree” button has to be clicked.
• A window as shown in figure will be displayed.

• To use Skype service, a Skype user account is needed. Click on the link with contents “Don’t have a Skype Name yet ?”, and then follow the procedure to create a Skype name.
• Once an account has been created, enter the Skype name and password as shown in figure and click on “Sign in” button.