~My preffered OS~

Insert the Windows XP CD into your computer and restart your computer.
If prompted to start from the CD press SPACEBAR. If you miss the prompt, restart the computer.
Windows XP setup begins. During this portion of setup, your mouse will not work, so you will have to use your keyboard on the Welcome to Setup page, press ENTER.
On the Windows XP Licensing Agreement page, read licensing agreement. Press the page down key to read the full agreement. Then press F8.
This page enables you to select the hard disk drive on which Windows XP will be installed
Press ENTER to select UN partitioned space, which appears by default or you have previously
Press ENTER again to select Format the partition using the NTFS file system, which appears by default.
Windows XP erases hard disk drive using a process called formatting and then copies of setup files. You can leave your computer and run to 20 to 30 minutes.
Windows XP restarts and then continues with installation process. From this point forward, you can use your mouse. Eventually the Regional and Language Options page appears. Click Next to accept the default settings.
On the Personalize Your Software page type you name and you organization name. Then, click next.
On the Your Product Key page, type your product key as it appears on you Windows XP CD case. The product key is unique for every Window XP installation. Then, click next.
On the Computer Name and Administrator Password page in the computer name box, type a name that uniquely identifies your computer. Then type a strong Administrator password retypes it in the Confirm password box. Write the password down and store it in secure place. Click Next.
On the Date a Time Setting page set your computer’s clock. Then, click the Time Zone down arrow, and select your time zone. Click Next.
Windows XP will spend about a minute configuring your computer. On the Networking setting page click next.
On the Workgroup or Computer Domain page, click next.
Windows XP will spend 20 or 30 minutes configuring your computer and will automatically restart when finished. When the Display Setting dialog appears, click OK.
When the Monitor Settings dialog box appears, click OK.
The final of setup begins. On the Welcome to Microsoft Windows page click next.
On the Help protect your PC page, click Help protect my PC by turning on Automatic Updates now. Then, click next.
Select yes and After the Completion of this Process go to the User name and enter the User name.
Once the Configuration is completed restart your Computer.
After installing it, Just Insert the Windows 7 DVD and install it simply following the Microsoft Tutorial but Don’t remove the other Drive on which XP is installed.
Now after restarting your PC you will ask to start the OS windows Xp or Other OS.
Soon we guys will update you with How to install Mac OSx on Windows PC so stay tuned to us.

MY PROTECTION & SECURITY

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

Some common categories are:

1. Casual prying by non technical users. Many people have terminals to

timesharing systems on their desks, and human nature being what it is, some of

them will read other people’s electronic mail and other files if no barriers are

placed in the way. Most UNIX systems, for example, have the default that all

files are publicly readable.

2.

Snooping by insiders. Student, systems programmers, operators, and other

technical personal often consider it to be a personal challenge to break the

security of the local computer system. They often are highly skilled and are

willing to devote a substantial amount of time to effort.

3.

Determined attempt to make money. Some bank programmers have attempted

to break into a banking system to steal from the bank. Scheme have varied from

changing the software to truncate rather than round interest, keeping the fraction

of a cent for themselves, to siphoning off accounts not used in years, to

blackmail

~FILE SYSTEM MANAGEMENT~

File system management objectives

A file management system is that set of system software that provides

services to users and applications related to the use of files.

include storage of data and the ability to perform the operations listed

earlier.

Concept and design

The operating system abstract from the physical

properties of its storage devices to define a logical storage unit, the file. File are

mapped, by the operating system, on to physical devices. This storage device are

usually non volatile, so the contents are persistent thru power failures and

systems reboots.

File directory

The directory is itself a file, owned

by the operating system and accessible by various to users and applications,

information is generally provided indirectly by system routines. Thus, users
cannot directly access the directory even in read-only mode

File Sharing 

Access Rights

The file systems provide a flexible tool for the following extensive file sharing

among users. The file system should provide a number of options so that the

way in which a particular file is accessed can be controlled.

To meet the data-management needs and requirements of the user, whichTo guarantee, the extent possible that the data in the file are valid

This relieves the user or programmer of the necessity of developing

special purpose software for each application and provide the system with a

means of controlling its most important asset.[GROS86] suggests the following

objectives for file management system:

~ INPUT OUTPUT MANAGEMENT~

The delay between submission and job completion (call

turnaround time) may result from the amount of computing needed, or

from delays before the operating system start to process the job.

The introduction of disk technology has help in this regard. Rather

then the cards being read from the card reader directly into memory

and then the job being process, cards are read directly from the card

reader onto the disk. The location of card images is recorded in a table

kept by the operating system. When the job is executed, the operating

systems satisfy its requests for card reader input by reading from the

disk. Similarly, when the job request to output a line, that line is

copied into a system buffer and is written to the disk. When the job is

completed the output is actually printed. This form of processing is

called spooling.

~ MEMORY MANAGEMENT~

Relocation

In a multiprogramming system, the available main memory is

generally shared among a number of processes. Typically it is not possible

for programmer to know in advance which are the programs that will

reside in the memory during the execution time of a program. In addition

we would like to be able to swap active processes in and out of main

memory to maximize processors usage by providing a large pool of ready

processes to execute.

Each process should be protected against unwanted interference by

other processes, whether accidental or intentional. Thus, programs in

other processes should not be able to reference memory locations in a

process, for reading and writing purposes without permission

Virtual memory can also work in a multiprogramming system. For example

eight 1M programs can each be allocated a 256K partition in a 2M memory,

which each program operating as though it had its own, private 256K machine.

In fact virtual memory multiprogramming fit together very well. While a

program is waiting for part of itself to be swapped in, it is waiting for I/O and

cannot run so the CPU can be given to another process.

The main problem of contagious allocation is external

fragmentation. This is overcome in the present scheme. Here a process is

allocated the physical memory where ever it is available, and this scheme

is call as paging scheme.

In the basic method physical memory is broken into fix size block

call frame. The logical memory also broken into block of the same size

called pages.

Every address generate by the CPU is divided into parts: a page

number (P) and a page offset (d). The page number p is use as an index

into a page table. The page table contains the base address of each page

lying in physical memory. The base address read from page table is

combining with page offset (d) to generate the physical memory address.

Before we consider ways of dealing with the shortcomings of partitioning,

we must clear up one loose end, which relates to the placement of processes in

memory. When the fix partition scheme is used, we can expect that a process

will always be a sign to the same partition. That is, the partition that is selected

when a new process is loaded will always be used to swapped the process back

into memory after it has been swapped up. When the process is first loaded all

relative memory references in the code are replaced by absolute main memory

addresess determine by the base address of the loaded process.

Now, consider that a process in memory include instructions plus data.

The instructions will contain memory references of the following two types;

some arithmetics and logical instructions.

Addresses of data items, used in load and store instructions and

instructions.Addresses of instructions, used for branching and called

Paging technique

Protection