You can target visitors using Adobe Target who use a certain operating system.
In the Target interface, click Audiences > Create Audience.
Name the audience and add an optional description.
Drag and drop Operating System into the audience builder pane.
Click Select, then select one of the following options:
(Optional) Set up additional rules for the audience.
The following illustration shows an audience targeting visitors using a Macintosh OS.
This video includes information about using audience categories.