Burn-In
Wonderful stuff. At the age of ten, my parents bought me a ZX-81 and I spent countless hours using it. My poor black and white TV got completely ruined in the end by "burn-in". Watching regular TV programmes got quite hard (as the picture got fuzzy) and images/listings that I left on the screen for too long ended up getting burnt in to regular viewing.
I went from the ZX-81 to a Vic-20, which seemed a novel thing as it had sound, colour, a larger memory and a fairly reliable dedicated tape drive.
I never looked back - I've been in IT most of my working life.