ttysys is a CPU and memory chart that shows a live updating percentage
history. The window can be split horizontally and vertically and show each
CPU core separately. RAM and swap are also available.
See ttysys's github page
I was looking for a terminal replacement to the Gnome System Monitor. I
occasionally break my GUI by kernel updates without NVIDIA updates or
something. I still like to be able to see a CPU chart, so I started looking
for one that would work at a text-only interface. I couldn't find one that
would show a percentage graph. The obvious answer was to make one.