Using "Enter the" to introduce a topic

Solution 1:

I think "enter the ASCII system" works perfectly! I would suggest that you start a new paragraph right after that sentence though.

Also, the grammar in your list about the problems of Morse Code is not as smooth as it could be. Try the following sentence instead:

Perhaps the biggest disadvantages are its steep learning curve and its difficulty to grasp, which may simply make it not worth your time and effort. Enter the ASCII system.

Solution 2:

"Enter the ASCII system." "Enter" is simply an introduction word to emphasize something not quite anticipated that follows. That "something" (ASCII) appears to be a solution for the issue at hand.