The author, Olivier de Broqueville designed this circuit for hi’s son who was dreaming of a small tool able to write symbols or pictures on a screen. The solution adopted was to pilot a matrix of Leds. This way, with only some cheap transistors, common red Leds, and a 16F628 , the dream could become reality.
Olivier also made a VB application that you can use to design patterns and export them apropriately.
Fancy LED matrix: [Link]