TUGASAN 1 (MEMORY MANAGEMENT)

Memory Management

This is the module of the Operating System that manages memory in a system by deciding when to allocate and de-allocate memory to a process, how much to allocate and the scheduling of these processes.  The following section lists the major concepts and terminologies that are related to Memory Management.

Virtual Memory

Virtual Memory refers to the concept whereby a process with a larger size than available memory can be loaded and executed by loading the process in parts.  The program memory is divided into pages and the available physical memory into frames.  The page size is always equal to the frame size.  The page size is generally in a power of 2 to avoid the calculation involved to get the page number and the offset from the CPU generated address.  The virtual address contains a page number and an offset.  This is mapped to the physical address by a technique of address resolution after searching the Page Map Table.

Paging

In Virtual Memory Systems, a program in execution or a process is divided into equal sized logical blocks called pages that are loaded into frames in the main memory.  The size of a page is always in a power of 2 and is equal to the frame size.  Dividing the process into pages allows non-contiguous allocation in these systems.

Segmentation

Segmentation is a memory management technique that supports Virtual Memory.  The available memory is divided into segments and consists of two components- a base address that denotes the address of the base of that segment and a displacement value that refers to the length of an address location from the base of that segment.  The effective physical address is the sum of the base address value and the length of the displacement value.

Memory Location Policy

The relocation policy specifies the thresholds of the overall system-supported metrics as well as policy window which is the time window to be used for metric history collected by the WPAR Manager agent, and agent polling time which states how long the agent should wake up to analyze policy violations.

Location Of Outdoor System
The output from these devices is input for the computer. Similarly, printers and monitors take as input signals that a computer outputs. They then convert these signals into representations that human users can see or read. For a human user the process of reading or seeing these representations is receiving input. These interactions between computers and humans is studied in a field called human–computer interaction.

RELOCATION OF PAGING SYSTEM
If your PC's hard drive is divided into partitions, moving your paging file may enable you to achieve better system performance. The paging file is an area of your hard drive that Windows uses as RAM in what is called "virtual memory." Follow these steps to relocate the paging file to a different partition than the one containing your Windows system files.

TUGASAN 2 (INPUT AND OUTPUT MANAGEMENT)

Input and 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 (My Preffered OS)

 Install or Format Windows 7

1) First, insert your Windows 7 Boot Disk into your dvd drive and reboot your PC.

While the PC is rebooting, you will be prompted ” Press any key to boot from CD…” Just press any key here.

2) Install Windows 7 - Press any key.

After you press a key, windows will load installation files.

Install Windows 7 - Windows is loading files.

Windows 7 setup will start.

3) Install Windows 7 - Starting Windows Setup.

Select your language, time and currency format and keyboard input (US).

4) Install Windows 7 - First Setup Screen, input language, time and currency format and keyboard input method.

Click Install Now to proceed.

5) Install Windows 7 - Install Now Screen.

Setup will load for a min or two.

6) Install Windows 7 - Setup is starting.

If you do, select I accept the license terms and click Next.

7) Install Windows 7 - License Terms.

If you are upgrading from Windows Vista select Upgrade, if you had Windows XP you have to select Custom (Advanced). Upgrade from Windows XP to Windows 7 is not available. Click Custom (Advanced).

8) Install Windows 7 - Custom Install.

Select the Partition where you want to install Windows 7 and click Next. You will need at least 5716mb free space.

9) Install Windows 7 - Where do you want to install windows.

If you don’t have enough free space to Install Windows 7, you will receive the following warning.

10) Install Windows 7 - Not enough disk space warning message will appear

If that’s the case, you will need to format the partition where you previously had Operating System installed. WARNING: Formatting a partition will erase all existing data on the partition, proceed only if you have backed up all your files!

If you want to format the partition, go to Drive options.

11) Install Windows 7 - Drive Options.

and format the partition where you want to install windows 7. Again, do this only if you have backed up your documents/files!

click format and then yes.

12) Install Windows 7 - Format Windows 7 Install Partition.

After you press Next, Windows 7 Installation will begin. Approximately takes about 30 min to 1 hour to finish, depending on your computer speed.

13) Install Windows 7 - Setup running.

After half an hour, setup is complete and windows 7 installation is almost finished. Few more minutes.

14) Install Windows 7 - Setup Complete.

Now your computer will reboot, since the Windows 7 DVD boot disk is still in the drive, the message press any key to boot from DVD will appear. We already did that, so this time DO NOT press anything. Just wait 5 sec and your PC will continue booting and finish installing your operating system.

15) Install Windows 7 - Setup Restarts.

16) Install Windows 7 - Dont press anything this time.

Windows will continue booting and installing.

17) Install Windows 7 - Windows starts to load.

18) Install Windows 7 - loading...

19) Install Windows 7 - Completing Installation.

20) Install Windows 7 - Setup is preparing your computer for first use.

      Insert your name (this will be your windows username).

21) Install Windows 7 - Type a username.

      If you want to, insert password for your computer. 

22) Install Windows 7 - Type your windows product key.

      Select use recommended settings.

23) Install Windows 7 - Use Recommended Settings.

      It’s time for Time zone, select yours from the drop down menu.

24) Install Windows 7 - Review your time and date settings.

      Depending on your location, select the appropriate network location.

25) Install Windows 7 - Computer location select network.

      If you have more than 1 computer, type homegroup password for sharing

      files.Make sure to remember it.

26) Install Windows 7 - Type homegroup password.

      Windows is finalizing your settings.

27) Install Windows 7 - Windows is finalizing your settings.

28) Install Windows 7 - Welcome screen.

      That’s it. Now insert your computer manufacturer drivers CD and

      install  drivers. Also FYI, Windows 7 has great driver support, go to

      Start –>    Control Panel –> Select View By = Small Icons –> Click 

      Windows Update.

29) Install Windows 7 - Windows Update.

      Check for updates and click on optional updates, to see which drivers 

     windows 7 found for your computer automatically.

     Finish.

3.0 : MEMORY MANAGEMENT

 

3.0: Elaborate on Memory Management Concept.

-         Memory management is the act of managing computer memory. In its simpler forms, this involves providing ways to allocate portions of memory to programs at their request, and freeing it for reuse when no longer needed. The management of main memory is critical to the computer system.

-         Virtual Memory systems separate the memory addresses used by a process from actual physical addresses, allowing separation of processes and increasing the effectively available amount of RAM using disk swapping. The quality of the virtual memory manager can have a big impact on overall system performance.

-         Garbage collection is the automated allocation and deallocation of computer memory resources for a program. This is generally implemented at the programming language level and is in opposition to manual memory, the explicit allocation and deallocation of computer memory resources. Region-based memory management is an efficient variant of explicit memory management that can deallocate large groups of objects simultaneously.

3.1            : Elaborate on Virtual Memory Implementation

-         The use of virtual memory addressing (such as paging or segmentation) means that the kernel (kernel is the central component of most computer operating system) can choose what memory each program may use at any given time, allowing the operating system  to use the same memory locations for multiple tasks.

-         If a program tries to access memory that isn't in its current range of accessible memory, but nonetheless has been allocated to it, the kernel will be interrupted in the same way as it would if the program were to exceed its allocated memory. Under UNIX this kind of interrupt is referred to as a page fault.

(Many operating systems can "trick" programs into using memory scattered around the hard disk and RAM as if it is one continuous chunk of memory called virtual 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.

-         In modern operating systems, memory which is accessed less frequently can be temporarily stored on disk or other media to make that space available for use by other programs. This is called swapping as an area of memory can be used by multiple programs, and what that memory area contains can be swapped or exchanged on demand.

3.1.1: Paging

-         In computer operating system, paging is one of the memory management schemes by which a computer can store and retrieve data from secondary storage for use in main memory. In the paging memory-management scheme, the operating system retrieves data from secondary storage in same-size blocks called pages. The main advantage of paging is that it allows the physical address space of a process to be noncontiguous. Before the time paging was used, systems had to fit whole programs into storage contiguously, which caused various storage and fragmentation problems.

-         Paging is an important part of virtual memory implementation in most contemporary general-purpose operating systems, allowing them to use disk storage for data that does not fit into physical random-access memory (RAM).

3.1.2: Segmentation

-         In computing, memory segmentation is one of the most common ways to achieve memory protection: another common one is paging. In a computer system using segmentation, an instruction operand that refers to a memory location includes a value that identifies a segment and an offset within that segment. A segment has a set of permissions, and a length, associated with it. If the currently running prosess is allowed by the permissions to make the type of reference to memory that it is attempting to make, and the offset within the segment is within the range specified by the length of the segment, the reference is permitted; otherwise, a hardware exception is raised.

-         Moreover, as well as its set of permissions and length, a segment also has associated with it information indicating where the segment is located in memory. It may also have a flag indicating whether the segment is present in main memory or not; if the segment is not present in main memory, an exception is raised, and the operating system will read the segment into memory from secondary storage. The information indicating where the segment is located in memory might be the address of the first location in the segment, or might be the address of a page table for the segment, if the segmentation is implemented with paging. In the first case, if a reference to a location within a segment is made, the offset within the segment will be added to address of the first location in the segment to give the address in memory of the referred-to item; in the second case, the offset of the segment is translated to a memory address using the page table.

-         In most systems in which a segment doesn't have a page table associated with it, the address of the first location in the segment is an address in main memory; in those systems, no paging is done. In the Intel 80386 and later, that address can either be an address in main memory, if paging is not enabled, or an address in a paged "linear" address space, if paging is enabled.

-         A memory management unit (MMU) is responsible for translating a segment and offset within that segment into a memory address, and for performing checks to make sure the translation can be done and that the reference to that segment and offset is permitted.

3.2 : Explain on memory relocation policy.

- In systems with virtual memory, programs in memory must be able to reside in different parts of the memory at different times. This is because when the program is swapped back into memory after being swapped out for a while it can not always be placed in the same location. The virtual memory management unit must also deal with concurrency. Memory management in the operating system should therefore be able to relocate programs in memory and handle memory references and addresses in the code of the program so that they always point to the right location in memory.

3.3 : Location of Outdoor System (best fir, worst fit, first fit).

Best Fit:

-         The allocator places a process in the smallest block of unallocated memory in which it will fit.

Problems:

-         It requires an expensive search of the entire free list to find the best hole.

-         More importantly, it leads to the creation of lots of little holes that are not big enough to satisfy any requests. This situation is called fragmentation, and is a problem for all memory-management strategies, although it is particularly bad for best-fit.

-         Solution:One way to avoid making little holes is to give the client a bigger block than it asked for. For example, we might round all requests up to the next larger multiple of 64 bytes. That doesn't make the fragmentation go away, it just hides it.

-         Unusable space in the form of holes is called external fragmentation

-         Unusable space in the form of holes is called external fragmentation

Worst Fit:

-         The memory manager places process in the largest block of unallocated memory available. The ides is that this placement will create the largest hole after the allocations, thus increasing the possibility that, compared to best fit, another process can use the hole created as a result of external fragmentation.

First Fit:

-         Another strategy is first fit, which simply scans the free list until a large enough hole is found. Despite the name, first-fit is generally better than best-fit because it leads to less fragmentation.

Problems:

-         Small holes tend to accumulate near the beginning of the free list, making the memory allocator search farther and farther each time.

Next Fit:

-         The first fit approach tends to fragment the blocks near the beginning of the list without considering blocks further down the list. Next fit is a variant of the first-fit strategy.The problem of small holes accumulating is solved with next fit algorithm, which starts each search where the last one left off, wrapping around to the beginning when the end of the list is reached (a form of one-way elevator).

3.4: Relocation of paging system - Least Recently Used (LRU), First In First Out (FIFO)

Least Recently Used (LRU):

-         Removes page least recently accessed

-         Efficiency

-         Causes either decrease in or same number of interrupts

-         Slightly better (compared to FIFO): 8/11 or 73%

-         LRU is a stack algorithm removal policy

-         Increasing main memory will cause either a decrease in or the same number of page interrupts

-         Does not experience FIFO anomaly

Two variations:

-         Clock replacement technique

-         Paced according to the computer’s clock cycle

-         Bit-shifting technique

-         Uses 8-bit reference byte and bit-shifting technique

-         Tracks usage of each page currently in memory

First In First Out (FIFO):

-         Removes page in memory the longest

-         Efficiency

-         Ratio of page interrupts to page requests

-         FIFO example: not so good

-         Efficiency is 9/11 or 82%

FIFO anomaly:

-         More memory does not lead to better performance