To show how Quexal redefines MMX/SSE programming, we will build a simple routine that computes the absolute difference between two images. Step 1 - The main window Here is the starting window of Quexal. At the center of the window lies the grid that contains the instructions that build up the source code. The main menu contains five sub menus: File, Edit, Run, Macro and Help. Some of the most important commands are replicated as icons on the first row of the toolbar. The second row of the toolbar lets you enter some of the most common MMX instructions quickly: even with a limited knowledge of the C language you are likely to understand most of these instructions without any help. If you don't remember what an icon means, just by moving the mouse pointer over it a balloon help will display a short explanation.