On the layout tab, Click View
tabViewports
panelNew.At the Command prompt,
enter vports.
In the Viewports dialog box, New Viewports
tab, under Standard Viewports, select Single.
Click to specify one corner of the new
layout viewport.
Click to specify the opposite corner.
A new layout viewport object is available and
displays a default view. To adjust the view, double-click within
the layout viewport to access model space.