Seven segment displays are useful for showing data, debug info such as addresses, etc. Instead of using a physical expansion board (wing) which costs money and has a limited number of digits, this simply uses an existing VGA output on a wing to implement any number of seven segment displays limited only by the available screen real estate.
In principle, if your project already uses the VGA output such as say PacMan, if should be quite easy to superimpose the seven segment display on top of the existing video output by logical ORing the seven segment display output with the existing VGA signal.
The position, size and color of each digit is configurable. A simplistic demo top module is included to generate some static and dynamic digits of various sizes and colors, see picture below.
Source Code : Source code on Google Code