Comment by rsync

Displaying graphics (of any kind) without a framebuffer is called "racing the beam" and is technically quite difficult and involves managing the real world speed of the electron beam with the cpu clock speed ... as in, if you tax the cpu too much the beam goes by and you missed it ...

The very characteristic horizontally stretched graphics of the Atari 2600 are due to this - the CPU was actually too slow, in a sense, for the electron beam which means your horizontal graphic elements had a fairly large minimum width - you couldn't change the output fast enough.

I strongly recommend:

https://en.wikipedia.org/wiki/Racing_the_Beam

... which goes into great detail on this topic and is one of my favorite books.