Dagen Brock, Assembly Language programmer of Flapple Bird, has released some videos about Assembly Programming on the Apple IIgs.
Introduction to Assembly Programming on the Apple IIgs - Lesson 0 (youtube.com)
This is an introductory video for programmers and hobbyists wanting to learn more about the Apple IIgs.
Introduction to Assembly Programming on the Apple IIgs - Lesson 0 Follow-up (youtube.com)
This revisits concepts from lesson 0 and responds to questions from viewers.
Introduction to Assembly Language Programming on the Apple IIgs - Lesson 1 (youtube.com)
Today's topic is Super High Resolution Graphics (SHR) and our first use of the CPU in 16-bit mode. Get the helpful Crash Course PDF here for an extra reference