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FORMAT WINDOWS VISTA

• Place the Windows Vista Upgrade disc in the optical drive. Close any dialog boxes that open.
• Turn off the computer, using the normal Windows shut down process.
• After the computer is turned off, disconnect all USB devices except the keyboard and mouse. This includes USB devices such as a printer, scanner, removable storage, or camera.
• Turn on the computer. When prompted, press any key to boot from CD or DVD.

• Windows loads files.

• In the Install Windows dialog box, select the appropriate information, and then click Next.

• In the Install Windows dialog box, click Install now.

• In the Type your product key for activation screen, enter the product key, and then click Next.

• In the Please read the license terms screen, check I accept the license terms, and then click Next.

• In the Which type of installation do you want screen, click Custom (advanced).

• In the Where do you want to install Windows screen, you can create new partitions, delete partitions, format partitions, and extend partitions. Make appropriate changes, and then click Next.
• This option creates a new hard drive partition.
• Click Drive options (advanced).

• Click New.

• Enter the appropriate partition size. Click Apply, and then click Next.

• The partition is created.

• Windows installs.

• The computer restarts.
• Windows prepares to start for the first time. This may take a few minutes. 

• Installation completes. 

• The computer restarts.
  Note: The following Out of Box Experience (OOBE) screens may vary slightly.
  
  
  
  
• In the Choose a user name and picture screen, enter the appropriate information, and then click Next.

• In the Type a computer name and choose a desktop background screen, enter the appropriate information and then click Next. 

• In the Help protect Windows automatically screen, select Use recommended settings. 

• In the Review your time and date settings screen, enter appropriate information and then click Next. 

• In the Thank You screen, click Start. 

• Windows checks the computers performance. Depending on hardware, this process could take from 3 to 15 minutes to complete. 

• Windows prepares the desktop.

• Windows Vista installation is complete.
• Any updated drivers and applications can be installed. It is recommended to update the antivirus definitions and perform Windows Updates.

PROCTECTION AND SECURITY

PROCTECTION AND SECURITY

opereting system protrction and security.explain and recognize security policy and mechanish,authentic basic also protection concept and access control.

Explain protection and security concept.

• Sharing of program and data among us a computer system necssitataes strong emphis on protection ang security measures in an os.Both protection and security imply guarding again -intrusion in an os. However,in keeping with the convention followed in os literature,a distinction is made between two types of intrusion.

Security policy and mechanism

• The term security and protection are often used interchangeable.Nevertheless, it is frequently useful to make a distinction between the general problems involved in making sure that files are not read or modified by unauthorized persons, which include technical, managerial, legal and political issues on the one hand, and the specific operating system mechanism used to provide security on the other to avoid confusion, we will use the term security to refer to the overall problem, and the term protection mechanisms to refer to the specific operating system mechanisms used to safeguard information in the computer. The boundary between them is not well defined, however.
• A more interesting problem is what to do about intruders. These come in two varieties. 
• Passive intruders just want to read files they are not authorized oread. Active intruders are more malicious; they want to make unauthorized changes to data.

Explain and recognize security policy and mechanish

• The separation of mechanism and policy is a design principle in computer science. It states that mechanisms (those parts of a system implementation that control the authorization of operations and the allocation of resources) should not dictate (or overly restrict) the policies according to which decisions are made about which operations to authorize, and which resources to allocate.
• This is most commonly discussed in the context of security mechanisms (authentication and authorization), but is actually applicable to a much wider range of resource allocation problems (e.g. CPU scheduling, memory allocation, Quality of Service), and the general question of good object abstraction.Per Brinch Hansen presented arguments in favor of separation of mechanism and policy. 
• Artsy, in a 1987 paper, discussed an approach for an operating system design having an "extreme separation of mechanism and policy".In a 2000 article, Chervenak et al. described the principles of mechanism neutrality and policy neutrality authentic basic also protection concept and access control.
• Effective security starts with understanding the principles involved. Simply going through the motions of applying some memory set of procedures isn’t sufficient in a world where today’s “best practices” are tomorrow’s security failures. IT security is a fast-moving field, and knowing how to perform the actions necessary for accepted practices isn’t enough to ensure the effective security starts with understanding the principles involved.
• Simply going through the motions of applying some memory set of procedures isn’t sufficient in a world where today’s “best practices” are tomorrow’s security failures.
• IT security is a fast-moving field, and knowing how to perform the actions necessary for accepted practices isn’t enough to ensure the best security possible for your systems.
• Among the most basic of security concepts is access control. It’s so fundamental that it applies to security of any type — not just IT security. Everything from getting into your car to launching nuclear missiles is protected, at least in theory, by some form of access control. 
• Because of its universal applicability to security, access control is one of the most important security concepts to understand.
• The key to understanding access control security is to break it down. There are three core elements to access control. Of course, we’re talking in terms of IT security here, but the same concepts apply to other forms of access control. 

Identification: For access control to be effective, it must provide some way to identify an individual. The weakest identification capabilities will simply identify someone as part of a vague, poorly defined group of users who should have access to the system. Your TechRepublic username, a PGP e-mail signature, or even the key to the server closet provides some form of identification.

Authentication: Identification requires authentication. This is the process of ensuring that the identity in use is authentic — that it’s being used by the right person. In its most common form in IT security, authentication involves validating a password linked to a username. Other forms of authentication also exist, such as fingerprints, smartcards, and encryption keys.
Authorization: The set of actions allowed to a particular identity makes up the meat of authorization. On a computer, authorization typically takes the form of read, write, and execution permissions tied to a username.

• These three elements of access control combine to provide the protection you need — or at least they do when implemented so they cannot be circumvented. 
• For the example of simple access to basic system utilities on a workstation or server, identification is necessary for accounting (i.e., tracking user behavior) and providing something to authenticate. 
• Authentication is necessary to ensure the identity isn’t being used by the wrong person, and authorization limits an identified, authenticated user from engaging in prohibited behavior (such as deleting all your backups).
• Depending on the type of security you need, various levels of protection may be more or less important in a given case. Access to a meeting room may need only a key kept in an easily broken lockbox in the receptionist’s area, but access to the servers probably requires a bit more care

INPUT OUTPUT MANAGEMENT

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

FILE MANAGEMENT

FILE MANAGEMENT

Also referred to as simply a file system or file system.

• 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.

MEMORY MANAGEMENT

Memory management

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 tomanual memory management, 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.

Process communication

Process in a computer system should work together for the user use to run their program. Communication between processes involves changing or sharing data which run using its scheme.

Mutual Exclusion

·         The successful use of concurrency among processes requires

the ability to define critical sections and enforce mutual exclusion. This is fundamental for any concurrent processing scheme. Any facility or capability that is providing support for mutual exclusion should meet the following requirements:

·         Mutual exclusion must be enforced: Only one process at a time in allowed into its critical section among all proceses that have critical sections for the same resource or shred object.

·         A process that has in its no critical section must do so withot interfering with other processes.

·        It must not possible for a process requiring access to critical section to be delayed indefinitely; no deadlock or starvation can be allowed

·         When no process is in a critical section, any process that requests entry to its critical section must be permitted to enter without delay.

·         No assumptions are made about relative process speeds or number of processes.

·         A process remains inside its critical section for a finite time only.

Synchronization

·         Consider a situation where a producer process produces an item which is consumed by consumer process. The producer process can produce an item, while the consumer process is consuming another item. The two events, consumer process and producer process must be synchronized so that the consumer process does not consume any item that has not yet been produced. In this  situation consumer must wait until the item is produced.

·         If we assume hat there is an infinite size buffer which can store the new items produced, then the consumer may have to wait for new items only. However, if the buffer is bounded size then the consumer must wait if the buffer is empty and the producer must wait if the buffer is full.

Deadlock

·         A system will have certain resources, like memory space, CPU cycles, files, I/O devices (such as printers, tape, etc), which may be requested by processes.

·         The resources are partitioned into several types, each of which consists of some number of identical instances.

·         If a process requests an instance of a resource type, the allocation of any instance of the type will satisfy the request. If it will not, then the instances are not identical and resource type class has not been defined properly.

                

·         A process would request a resource it needs, and must release the resource after using it. And a process may request several resources which it may need for its accomplishment.

·         A process will use the resource in the sequence request use and release. The request and release of resources are system calls, like, request device, open file, close file and allocate memory.

·         To make sure that the using process has requested and been allocated the resource, the request and release of resources can accomplish through the wait and signal semaphores.

Dead-Lock Definition

·         A set of process is in a deadlock state when every process in the set is waiting for an event that can be caused by only another process in the set. The events in the set are acquisition and release.

Deadlock Characterization

·         A deadlock situation can arise if all the following four conditions are held simultaneously in a system. They are:

·         Mutual exclusion: at least there should be one resource in non-sharable mode and only one process at a time can use the resource. If a resource is occupied by a process and another process requests that resources the requesting process must be delayed until the resource has been released.

·         Hold and wait: There must exist a process that is holding at least one resource and is waiting to acquire additional resources that are currently being held by other processes.

·         No Pre-emption: Resources cannot be pre-empted that is a resource will be released only after the process holding it has completed its task.

Deadlock Avoidance

·         In this approach some additional information (about how resources will be requested) is used. With this knowledge (sequence of requesting and release of resources) suitable allocation strategy is arrived, avoiding deadlock.

·         One of the algorithms to avoid deadlock is that each process declare the maximum number of resources of each type it may need. With this information a prior, it is possible to construct an algorithm that ensures that system will never enter a deadlock state.

·         If a system does not have either deadlockprevention or a deadlock avoidance algorithm then a deadlock situation may occur. Under this situation, the system should have deadlock detection mechanism and strategy to recover from it.

Deadlock Avoidance

·         We explain this by assuming that resources in the system has only single instance. But we do is from resource allocation graph, derive another graph called as wait graph.

·         This wait graph is obtained from resource graph by removing the nodes of type resource and collapsing the appropriate edges.

 Recovery from deadlock

·         After detection of deadlock, several actions are possible. The possible action could be to let the operator deal with deadlock manually. Other method could be automatic recovery from deadlock. Deadlock could be broken by aborting one or more processes to break the circular-wait condition.

·         For recovery from deadlock, there is a need to terminate the process. One approach is to terminate all the processes involved in deadlock. This will result into complete loss of all processes and its results.

·         The other approach is to about process one by one at a time until the deadlock is eliminated however this method is time consuming. Also we need to identify which process should be terminated first. This may depend upon many factors like priority of a process, present state of the process.

·         The approach of eliminating deadlocks using resource pretemption, calls for successive pretemption of some resources from process and allocate them to other waiting process until the deadlock cycle is broken.

·         However the factors which need to be considered in this approach are: selection of a victim resource to be aborted, roll backing of the process for which the resource is pre-empted and to ensure that starvation will not occur.

Process Synchronization

Situation where the correctness of the computation perfomed by cooperating processes can be affected by the relative timing of the processes execution is called a race condition. To be considered correct, cooperating prosesed may not be subject to race condition. When cooperating processes run on a system with a single processor, concurrency is simulated by the processes sharing the CPU. The scheduling algorithm determines the relative timing of cooperating processes. The result may differ widely from an idealized perception of parallel execution. Not only is timing dependent on the scheduling algorithm used, it also depentdent on the system load created by other proceses on the system. On multiprocessor systems, there is no guarantee all processor work at equivalent speeds. Depending on which processes are allocated to which processors, timing can differ drastically.