Your post just clicked something from of a deep memory into place.

In the early 80s when the IBM PC hit the scene, Hercules had a graphics card that was amazing and offered better than CGA graphics. I was plinking on it at my dad’s friend’s house, drawing circles and stuff, and on HIS computer the graphics were retained. I had to figure out how to clear the screen, whereas on mine, not having the Hercules card, it wasn’t retained. Never understood what was happening until now.