The lion kingdom originally wanted just a command line audio editor. It would draw the waveform in ASCII or embed monochrone graphics in the xterm, using the regis protocol or custom character sets.
XTerm does draw graphics in the same window as the text. It has to be compiled using configure --enable-regis-graphics
Then it has to be run as xterm -ti vt340
draws some simple graphics.
You might use this to have an embedded system draw graphics through a serial port.
It should be noted the regis protocol doesn't work inside the screen program. That wraps stdout in some other codes.