“I remember him telling me the reason behind the blinking cursor, and it was simple,” Charles “Chuck” Kiesling’s son writes. “He said there was nothing on the screen to let you know where the cursor was in the first place. So he wrote up the code for it so he would know where he was ready to type on the Cathode Ray Tube.”

The blinking, it turns out, is simply a way to catch the coders’ attention and stand apart from a sea of text.