Z80 Assembly
Patai Gergely’s Z80 Assembly is a low level guide to assembly programming. As Gergely states:
Assembly is a low level language… The Z80 does not even know how to multiply two numbers! This is up to you to code. I will try to teach you how to manage on your own. Please, be patient.
“Please, be patient,” summarises the challenge of teaching, neatly.