Start by opening the quartet file in vi. Enter the set command to list options that have changed from their defaults, including those that you did not explicitly change within your session. The set command lists three changed options: redraw, showmode and term=vt100. Their default values are noredraw
The redraw and term options ensure that vi correctly displays text on your terminal. UNIX defines your terminal settings at log in and passes them to vi through the redraw and term options.
You can explicitly change options within your version. Later on, you can enter the set command to check your options again. The listing now shows the ignorecase option that you turned on.