My take: That's what the spacebar is. Originally the backspace key did the inverse. This probably worked a lot more like what we think of as "overwrite" mode

My take: That's what the spacebar is. Originally the backspace key did the inverse. This probably worked a lot more like what we think of as "overwrite" mode on early terminals. The "delete" character is something else entirely. It seems to have been invented to wipe (literally "delete") a position on a paper tape, for example. That's the reason its character code is all ones (in the seven bit code of the time). The ones were holes, and you could "delete" any other character (a mix of holes and not-holes) by punching a hole in every position. A lot of the rest is just historical accident.