How to set up Hard disk boot priority

If you have two OS.For example Debian in one Hard Disk and Ubuntu
in other hard disk.Then if we want any one os to boot then what
to do.Now to set up the hard disk priority.

1. At first the Debian harddisk should be connected to SATA-0 of the
   systems mother board and Ubuntu harddisk shoud be connected to
   SATA-1 of systems mother board.

2.Then enter into 'BIOS setup' press the 'Delete Key' while
   you start up your system.

3. After entering the 'BIOS setup' enter into 'Advanced BIOS features'

4. Now enter into the 'Hard disk boot priority'

5. After entering the 'Hard disk boot priority' now select the
   boot priority.

6. There will be two boot priority in this system.

7. The two priority will be as follows
   Ch2 S  -(Ubuntu)
   Ch1 M  -(Debian)

8. If we want debian then 'Ch1 M' should be moved to the top position.

9. Now save the set up by pressing the 'F10'.

10. Then the procedure is as usual  boot the OS and login.