Understanding the special 'line terminator' characters

Here is the original Microsoft, pre-Dos text box.  Much of modern computer science is built around this device, and Bill Gates great grandfather made some software compromises.

As you can see, in this personal computer, the display screen moved and the mouse is relatively fixed!  The mouse  is that mechanical arm to the left.  When the text box reached the end of the line, it hit a mechanical bell and that notified the human to whack that arm (kind of like a double click).  When he hit that arm, the cursor (or LCD display)  moved to the beginning of the current line, and then down one line, mostly.

By mostly I mean there was a dispute. Some manufactures want that arm to do the line feed first, then return the carriage, citing mass inertia.

Today we still have that dispute, but things stay the same.  When my cursor hits the end of the text window, the mechanical bell still dings.  I miss the moving screen, though.  On my cluttered desk,there isn't much room for mouse, and I often do  drag the mouse of the table edge.  If I  could get a swivel computer, one that monitored my mouse and sort of swung out of the way when I mouse way off to the left.

How did they do graphics in olden times?

The machine, it had a push button at the left end of the carriage. You can just see it, it was like the right mouse button of today.  Your left hand grabbed the carriage handle, pushing in that button. The carriage would them roam free, to the pixel level, while you right hand found unusual and confusing characters to type.