you need
  • computer with two operating systems.
Once you install a second operating system , turn on the computer.At boot time, the system should have a dialog box in which you will have a list of operating systems that are installed on your hard drive.
Use arrow keys to select the operating system that you need at the moment, and press Enter.After that you selected the operating system will boot normally.
If a dialog box in which you could choose the operating system did not appear, but just one of the operating system has booted, you need to enter some settings.To do this, right click on the icon "My Computer" and then click "Properties".In the next windo
w click on "Advanced system settings."
then in "Advanced" tab, locate the section titled "Startup and Recovery" option and select it in "Settings".Find item "Display list of operating systems" and mark it.Then click OK.In the next window and click OK.
Restart the computer.Now a dialog box where you can select the operating system will be accurate.
If you have a computer has two hard disks, and each is running, a window for selecting the operating system may not appear.In this case, you can select the operating system by selecting the hard drive, which set the desired operating system.
Turn on the computer and then immediately press repeatedly Del.So you get into the BIOS of the computer.Now, with the help of arrows on the keyboard, select the boot device priority.In this section, the digit "1" Put the hard disk to the right at the moment the operating system.Save the settings.The computer restarts and starts from the selected hard drive with the right OS.