RESEARCH TOPIC

A.Research the size of operating system software by finding the amount of secondary storage(disk) space required of the same operating system or different operating systems. If their sizes are substially different, explain why that may be the case, such as platform issues, features, etc. Cite your sources.

a n s w e r

  The sizes of software updates may vary. This is a feature of Software Update.

 Software Update is able to offer a "smaller-sized Delta" update than you might expect for Mac OS X v10.3.4 and later, or smaller than what you might see on other computers installing the same update. The "smaller Delta" updates are offered when some Mac OS X system files can be modified instead of replaced in their entirety.

B.Consult currennt literature to research file-naming conventions for four different operating systems. Note the acceptable range of characters, maximum length, case sensitivity, tc. Give example of both accetable and unacceptable filenames. For extra credit, how File Managers for those operating system shorten long filenames in their internal lists to make them easier to manipulate.Cite your sources.

a n s w e r


Use a period to separate the base file name from the extension in the name of a directory or file.

• Use a backslash (\) to separate the components of a path. The backslash divides the file name from the path to it, and one directory name from another directory name in a path. You cannot use a backslash in the name for the actual file or directory because it is a reserved character that separates the names into components.
• Use a backslash as required as part of volume names, for example, the "C:\" in "C:\path\file" or the "\\server\share" in "\\server\share\path\file" for Universal Naming Convention (UNC) names. For more information about UNC names, see the Maximum Path Length Limitation section.
• Do not assume case sensitivity. For example, consider the names OSCAR, Oscar, and oscar to be the same, even though some file systems (such as a POSIX-compliant file system) may consider them as different. Note that NTFS supports POSIX semantics for case sensitivity but this is not the default behavior. For more information, see CreateFile.
• Volume designators (drive letters) are similarly case-insensitive. For example, "D:\" and "d:\" refer to the same volume.
• Use any character in the current code page for a name, including Unicode characters and characters in the extended character set (128–255), except for the following:
  • The following reserved characters:
    • < (less than)
    • > (greater than)
    • : (colon)
    • " (double quote)
    • / (forward slash)
    • \ (backslash)
    • | (vertical bar or pipe)
    • ? (question mark)
    • * (asterisk)
  • Integer value zero, sometimes referred to as the ASCII NUL character.
  • Characters whose integer representations are in the range from 1 through 31, except for alternate data streams where these characters are allowed. For more information about file streams, see File Streams.
  • Any other character that the target file system does not allow.
• Use a period as a directory component in a path to represent the current directory, for example ".\temp.txt". For more information, see Paths.
• Use two consecutive periods (..) as a directory component in a path to represent the parent of the current directory, for example "..\temp.txt". For more information, see Paths.
• Do not use the following reserved names for the name of a file:
  CON, PRN, AUX, NUL, COM1, COM2, COM3, COM4, COM5, COM6, COM7, COM8, COM9, LPT1, LPT2, LPT3, LPT4, LPT5, LPT6, LPT7, LPT8, and LPT9. Also avoid these names followed immediately by an extension; for example, NUL.txt is not recommended. For more information, see Namespaces.
• Do not end a file or directory name with a space or a period. Although the underlying file system may support such names, the Windows shell and user interface does not. However, it is acceptable to specify a period as the first character of a name. For example, ".temp".

Short vs. Long Names

A long file name is considered to be any file name that exceeds the short MS-DOS (also called 8.3) style naming convention. Typically, Windows stores long file names on disk as special directory entries, which can be disabled systemwide for performance reasons depending on the particular file system. When you create a long file name, Windows may also create a short 8.3 form of the name, called the 8.3 alias, and store it on disk also. This 8.3 aliasing can be disabled for a specified volume.

Windows Server 2008, Windows Vista, Windows Server 2003, and Windows XP:  8.3 aliasing cannot be disabled for specified volumes until Windows 7 and Windows Server 2008 R2.

http://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx

EXERCISES



1. Explain in your words why file deallocation is important and what would happen if it did not occur on a regular basis.

 --->> Lets define first the word File Deallocation, to remove from the set of resources put aside for (allocated to) a particular user or purpose.File manager deallocates a file by updating the file, tables and rewriting the file so if there's no deallocation the file couldn't update files.

2. Describe how the File Manager allocates a file to a single user. List the steps that you think would be followed and explain your reasoning.

--->> File Manager allocates a file to a single user through read, write, modify , create, and delete.

3.Is device independence important t the File Manager? Why or Why not ? Describe the consequences if that were not the case.

--->> NO its important because  device independence is the process of making a software application be able to function on a wide variety of devices regardless of the local hardware on which the software is used therefor File Manager can still manage files even there's it is.

4. Do you think file retrieval is different on a menu-driven system and a command-driven system ?Explain your answer and describe any differences between the two. Give an example of when each would be prefeered over the other.

--->>Yes its defferent because File retrieval or File recovery are those  files you have already deleted and then recently emptied from your Recycle Bin are often still present on your hard drive (or USB drive, or media card, etc.) and can be recovered using free file recovery software but Command driven refers to programs and operating systems that accept commands in the form of special words or letters. (Example in verification, you need to have a code to verify your account) .In contrast, programs that allow you to choose from a list of options in a menu are said to be  Menu-driven( example when you forgot your password ,there were a lot of choices in Menu for you to use again your account).  Command-driven software is often more flexible than menu-driven software, but it is more difficult to learn.

5. Imagine one real-life examples of each: a multi-file volume and a multi-volume file. Include a description of the media used for storage and a general description of the data in the file. 

--->> A  multi-file volume are containing many files in a single file which is compressed to a smaller size( ex. In text message, you need to send it to a lot of person because its an important announcement, so for you to send it once you need to "SEND  TO MANY" the message) . A multivolume file are files that consists of more than one physical unit of storage medium.

6. As described in this chapter, files can be formatted with fixed-length fields or variable-length fields. In your opinbion, would it be feasible to combine both formats in a single disk ? Explain the reasons for your answer.

--->> Variable-length fields are useful because they save space. A Fixed-length record is one in which every field has a fixed length. YES its feasible because its the same way of formatting files.

7. Explain why it's difficult to support direct acess to files with variable-lenght records. Suggest a method for handling this type of file if direct access is required.

--->> Its difficult to support direct acess to files with variable-length records because it depend on what  data  is stored in the field.

8. Give an example of the names of three files from your own computer that do not reside at the root or master directory. For each file, list both the relative filename and its complete filename.

--->>