Well this is something that I've started to develop a while back. However it is nearly complete. In the meantime I'm getting what I have out while it is still fresh in my head.
What is unique about this software is not that it is in DOS but that the character reader is flexible and portable. With enough processing power you can fly a message in any pattern you want whether it be in a circular motion or a straight line or even standing still!
However DOS doesn't have enough processing power so it is enormously slow.
Anyways I have incorporated it into the Imitation Lode Runner Game beginning. It just says "Jesus Christ always wins" along with my two parents' name: mom Huong Thi Vu and dad Nguyen Binh Thuy!
The source code is included along with the flexible character definition. If it locks up on you that means you hex edited to one of the character definition that was not properly formatted.
