Over at davebr’s “My Tektronix Memories” page, he has a really great video of the Tektronix 4010 terminal demonstrating various features of the DISSPLA graphics software. This is a video taken of the screen of the terminal as it renders the demonstration file at 2400 baud. This gives you a very good representation of what using these terminals was like. You watched a bright spot move across the screen as it stroked the graphics onto the storage tube. If you look carefully, you can see the alphanumeric cursor blinking in the lower left side of the screen as the file transmits a bunch of NUL characters to the terminal in order to implement a delay in the presentation. The bright full-screen flash is the mechanism used to erase the screen before drawing the next picture.