Mac OS X allows you to rotate your screen display using System Preferences. Landscape and Portrait Mode can be set using Displays Option of System Preferences. You can even change Display Resolution using the Displays Icon of System Preferences. In order to view / change the display options on your Mac OS X, open up System Preferences, locate the Displays Icon and open it as displayed below.
The Displays Icon is located in Hardware Section of System Preferences of Mac OS X. Whether you are using Single , Dual or Multiple Monitor Mac OS X, this Displays option of System Preferences is the software option to view / configure display parameters. You will be able to identify monitor using the monitor name in the System Preferences of Displays option.
In order to rotate your display to Portrait or Landscape mode, you can select any of the Rotation option available. Whether your display can be rotated or not will depend on the functionality supported by your Display Driver, Graphics Card etc. Display in Mac OS X can be rotated in steps of 90 degrees. Once you change the rotation parameters, a popup will appear to confirm or revert back the new display settings. By default the focus on this confirmation screen will be on the Revert button which can be pressed by pressing the Enter Key on Keyboard. Mouse Movement direction will also change depending on the orientation of the display and hence knowledge of Keyboard Shortcut can be really useful.
In order to change the Display Resolution, this System Preferences is the only default option. There is no keyboard shortcut by default to change the display orientation and instead the only keyboard shortcuts available for Displays are to Increase or Decrease display brightness. In order to view the available keyboard shortcuts on your Mac, view the global keyboard shortcut post which displays how to view and change Mac OS X Global keyboard shortcuts. The above screenshot has been captured on Mac OS X Lion (Version 10.7) and the latest Mac OS X Version is Mac Mountain Lion (Version 10.8).