Tugasan OS

Tugasan 1..

Memory management especially the objectives and memory management concept. Elaborate on virtual memory implementation such as paging and segmentation. Explain memory relocation of paging system

Objectives Memory Management

• ·         To provide a detailed description of various ways of
• ·         organizing memory hardware.
• ·         To discuss various memory-management techniques,
• ·         including paging and segmentation.
• ·         To provide a detailed description of the Intel Pentium, which supports both pure segmentation and segmentation with paging.

Concept Memory Management

• ·         Program must be brought (from disk) into memory and placed within a process for it to be run.
• ·         Main memory and registers are only storage CPU can access directly.
• ·         Register access in one CPU clock (or less).
• ·         Main memory can take many cycles.
• ·         Cache sits between main memory and CPU registers.
• ·         Protection of memory required to ensure correct operation.

virtual memory implementation

virtual memory is a memory management technique developed for multitasking kernels. This technique virtualizes a computer architecture's various hardware memory device (such as RAM modules and disk storage drives), allowing a program to be designed as though:

• ·                     there is only one hardware memory device and this "virtual" device acts like a RAM module.
• ·                     the program has, by default, sole access to this virtual RAM module as the basis        for a     contiguous working memory.

-       When the kernel detects a page fault it will generally adjust the virtual memory range of the program which triggered it, granting it access to the memory requested. This gives the kernel discretionary power over where a particular application's memory is stored, or even whether or not it has actually been allocated yet.

Segmentation

• ·         Memory-management scheme that supports user view of memory
• ·         A program is a collection of segments. A segment is a logical unitsuch as:

-         - main program,

-          -procedure,

-          -function,

-          -method,

-          -object,

-          -local variables, global variables,

-          -common block,

-          -stack,

-          -symbol table, arrays

PAGING

• ·         Logical address space of a process can be noncontiguous; process is allocated physical memory whenever the latter is available
• ·         Divide physical memory into fixed-sized blocks called frames (size is power of 2, between 512 bytes and 8,192 bytes)
• ·         Divide logical memory into blocks of same size called pages
• ·         Keep track of all free frames
• ·         To run a program of size n pages, need to find n free frames and load program
• ·         Set up a page table to translate logical to physical addresses
• ·         Internal fragmentation

Explain memory relocation of paging system

Paging permits a program to be allocated noncontiguous blocks of memory. We divide programs into pages which are blocks of small, fixed size. We then divide the physical memory into frames which are blocks of size equal to page size. We use a page-table to map program pages to memory frames.
The page size (S) is defined by the hardware. Generally it ranges from 512 words/page to 4096 words/page.

Tugasan 2

INPUT & OUTPUT MANAGEMENT

• Managing input & output in Windows XP involves many operating system componets.
• User-mode processes interact with an enviroment subsystem and not directly with kernel-mode componets.
• The enviroment subsystem pass input & output request to the input & output manager,which interacts with devices drivers to handle such request.
• Sereval device drivers,organized into a driver stack,cooperate to fulfill an input & output request.
• The plug and play manager dynamicaly recognizes when new devices are added to the system and allocates and deallocates resources,such as input & output ports or DMA channels, to them.
• The power manger administers the operating system’s power mangement policy.
• The power policy detemines whether to power down devices to conserve energy or keep them fully powered for high responsiveness.

 Elaborate the concept of buffering 

• Buffer overflow weakness is one of the many disadvantages of this type of security computer
• Buffer overflow attacks occur when the excessive Attacker provide input on the plan on the run
• Buffee overflow results from the weakness of the programming language c, c + +, fortran, and assembly, which does not automatically check the limit input when the program is executed
• The program is so complex, sehinnga programmers themselves do not know the weaknesses of the program
• Relies on external data to control the program
• Buffer is provided at the memory allocation, such as arrays or pointers in C. in the language C and C + +, there is no automatic restrictions on buffernya, where users can write through the input buffer. For example:

int main () {
int buffer [10];
buffer [20] = 10;
}

• Program in C above is a valid program, and each compiler to compile without error
• A process is a program in execution.

Recognize spooling technique

• In computer science, spooling refers to a process of transferring data by placing it in a temporary working area where another program may access it for processing at a later point in time.
• The normal English verb "spool" can refer to the action of a storage device that incorporates a physical spool or reel, such as a tape drive.
• Spooling refers to copying files in parallel with other work.
• The most common use is in reading files used by a job into or writing them from a buffer on a magnetic tape or a disk.
• Spooling is useful because devices access data at different rates. The buffer provides a waiting station where data can rest while the slower device catches up.
• This temporary working area would normally be a file or storage device.
• The most common spooling application is print spooling: documents formatted for printing are stored onto a buffer (usually an area on a disk) by a fast processor and retrieved and printed by a relatively slower printer at its own rate.
• Spooler or print management software may allow priorities to be assigned to jobs, notify users when they have printed, distribute jobs among several printers, allow stationery to be changed or select it automatically, generate banner pages to identify and separate print jobs, etc.

• The temporary storage area to which E-mail is delivered by a Mail Transfer Agent and in which it waits to be picked up by a Mail User Agent is sometimes called a mail spool.

TUGASAN 3 (FILE SYSTEM MANAGEMENT)

File Sharing

• The system that an operating system or program uses to organize and keep track of files.
• For example, a hierarchical file system is one that uses directories to organize files into a tree structure.
• Although the operating system provides its own file management system, you can buy separate file management systems.
• These systems interact smoothly with the operating system but provide more features, such as improved backup procedures and stricter file protection.

File Sharing

• Sharing of files on multi-user systems is desirable
• Sharing may be done through a protection scheme
• On distributed systems, files may be shared across a network
• Network File System (NFS) is a common distributed file-sharing method

Directory Structure

• A collection of nodes containing information about all files.
• Both the directory structure and the files reside on disk.
• Backups of these two structures are kept on tapes

File Mapping

• File mapping is the association of a file's contents with a portion of the virtual address space of a process.
• The system creates a file mapping object (also known as a section object) to maintain this association.
• A file view is the portion of virtual address space that a process uses to access the file's contents.
• File mapping allows the process to use both random input and output (I/O) and sequential I/O.
• It also allows the process to work efficiently with a large data file, such as a database, without having to map the whole file into memory.
• Multiple processes can also use memory-mapped files to share data.
• Processes read from and write to the file view using pointers, just as they would with dynamically allocated memory.
• The use of file mapping improves efficiency because the file resides on disk, but the file view resides in memory.
• Processes can also manipulate the file view with the Virtual Protect function.

TUGASAN 4 (PROTECTION AND SECURITY)

Recognize security policy and mechanism.

   In computer science, protection mechanisms are built into a computer architecture to        support the enforcement of security policies. A simple definition of a security policy 

   set who may use what information in a computer system.Mechanism for controlling the   

   access of programs, processes, or users the resources defined by the computer

   system. the protentation mechanism ensures the enforcement of a certain policy.

 Elaborate authentic basic.

Password

        A password is a secret word or string of characters that is used for authentication, to prove identity or gain access to a resource (example: an access code is a type of password). The password should be kept secret from those not allowed access.

Artifact

     In natural science and signal processing, an artifact is any error in the perception or  representation of any visual or aural information introduced by the involved equipment or technique(s).

         In computer science, digital artifacts are anomalies introduced into digital signals as a    

            result of digital processing.

         In microscopy, artifacts are sometimes introduced during the processing of samples into   

            slide form. See Artifact (microscopy)

Biometric

       Biometrics consists of methods for uniquely recognizing humans based upon one or more

          intrinsic physical or behavioral traits. In computer science, in particular, biometrics is

          used as a form of identity access management and access control. It is also used to

          identify individuals in groups that are under surveillance.

Elaborate protection concept and access control.

·         For your PC security suite is now available a variety of programs that promise more often than full protection from malware, with acontrol virus and malware, but also with some research andcomplex in real time. 

·        Major challenge for all manufacturers areoffering solutions that are effective yet easy to use, and if you do not require excessive resources to the system.

·         At the time all the leading manufacturers of security software suite that provides a guide as well as the traditional functions of malwaredetection and protect your PC also features accessories forprotection of data and optimization of the operating system. 

·         The concept of security was also extended to the area where this malware is not in the strict sense. But, in a sense, a proper backup data fall within the concept of security

TUGASAN 5

Introduction

The format is intended to remove the computer and remove viruses on the computer.This may be due to computer viruses like Worm, Spyware, or Trojan horse thatinterferes with computer systems. Computer format aims to upgrade the operating system (OS) of the old to the new.

 Steps - Step


Set the Boot Sequence to CD-ROM

To ensure that your computer will read the Windows XP CD to be inserted, bootsequence should be assigned to the CD-ROM first. In most computers, this setting is already set, so you do not have to worry anymore. You can continue to format theHard Disk if there is no problem here.

But if your computer does not read from the CD-ROM, follow these steps to set theboot sequence:


     1.Switch  your computer.
     2.Press F2 button (on some computers, you must press the DELETE)
         to launch the BIOS.
     3. In Phoenix BIOS, select Advanced BIOS Features.



    4.  Select Boot Sequence.

5. In the Boot Sequence sequence, set the CD-ROM is at the top.




    

 6. Press F10 to save settings and restart your computer.

Format Hard Disk

1.First, you'll see a screen with the message "Press any key to boot from CD ...".Press any button here so that the computer will start reading from the Windows XPCD

2. Consider first the message out, "Press F6 if you need to install a third party SCSI or
or RAID driver. "This message is important if you install Windows XP on the HardDisk
SATA. If yes, press F6 and insert the SATA disk that came with the motherboard
you. If not, ignore this message and proceed to step 3. (Note: If you want to install
Windows XP to a SATA Hard Disk, but no floppy, follow these steps:

3."Welcome to Setup" is displayed. Press ENTER to start to install Windows XP.

4. If you see the screen "Setup did not find any hard disk" is most likely that you areusing
     SATA hard disk. Return to Step 2, or follow these steps. 

5. “Windows XP Licensing Agreement”. Press F8 to proceed.

6. If you have a hard hisk Windows XP, Setup will ask if you want to repair the old tuWindows XP. Press the ESC because you want to install a new Windows XP.

7. If your hard disk:
 - are new and have not had any partition, follow steps 7 to 8.
 - but if it has no partition in it, proceed to step 9.




8. Create a partition by pressing C.

9. Determine the size of your partition and press ENTER

10. Choose a partition C: to install Windows XP. Note: If you have any important files anddocuments in the partition C:, create a backup of the data transfer to the partition D:or to the external hard drive.

11. Press button C to agree.

12. Choose NTFS as the file system and press ENTER.

13. Press F to format Hard Disk.

14. Setup will start formatting your hard disk and prepare files for the Windows XPinstall. Once this process is complete, your computer will restart by itself

Install Windows XP

1. Windows XP install process begins. Click the Next button.

 2. Enter your name and click the Next button.

3. Enter the serial number for Windows XP and click the Next button.




                                        


 4. Enter a password for the Administrator and click the Next button.

5. In the Time Zone field, select the Kuala Lumpur and click the Next button.

6.  Setup process has begin. Wait until finished.

7. If you have a Network Card, Setup will ask you to make choices about theNetwork. Just click on the Next button twice.

8. Wait until the entire Windows XP install process is complete, and the computerwill restart again.


Start Using Windows XPThe first time Windows XP started, your screen resolutionbe amended as appropriate. Click on the OK button.

2. "Welcome to Microsoft Windows" is displayed. Click the Next button.

3. Select "Not right now" and press the Next button. You can re-enable AutomaticUpdates in the future.

4. Windows will attempt to detect your Internet connection. You may omit this stepby clicking Skip.

5. Select "No, not at this time" so you do not need to register with Microsoft. Press the Next button.

6. Enter your name and click Next.

7. 

8. Now, Windows XP was installed and ready you can already start using it.

9. Formatting process is finished.