I am trying to learn to make graphical programs with assembly language. I do not want any external libraries. If I have to download something (after already downloading the assembler itself of course) it is an external library. I want to use the equivalent of Linux system calls for Ubuntu GUI. Obviously, I can’t use system calls for GUI if I am on Ubuntu because Ubuntu’s GUI program is separate from Linux.
Do not answer with a recommendation for an external library or by advising me to stay away from “low level” computing. Do not answer by saying it is not possible either, for if it wasn’t possible, how do the external libraries do it? The reason I include this paragraph in the question is that such answers are common for lower level computing questions.