Area 5150 (Demoscene)

I'm no expert but I was around and programming assembler graphics back when that hardware was new (although I had a 6809 Radio Shack Color Computer). What they are showing was thought to be impossible on that hardware. No common games or graphics apps on that hardware back then ever showed:

* Updating the entire screen at faster than slide show rates.

* The graphics card had no modes which could display that many colors or that (apparent) amount of resolution. These wizards are leveraging several tricks including having the (very slow) processor babysit the display beam and change color palette and mode registers synchronized on a per scan line basis.

* They are creatively using graphical artifacts which arise from composite video modes. When black and white pixels are placed too close together in exactly the right way, an analog television misinterprets the signal as color burst and creates ghost colors. They are making art out errors showing color patterns the hardware technically can't make.

* They are interleaving text-only display modes with pixel modes and semi-graphics character modes on the screen at the same time.

* There is no graphics support in the hardware for things like bit blitting. They are doing everything with the CPU by meticulously planning every pixel and allocating every single available CPU cycle on every frame. Anytime you see a scan line not moving or changing color, you can safely assume there were no more CPU cycles left for that frame after endless hand-optimization.

They are showing unbelievable assembly language coding skills combined with down-to-the-metal arcane hardware knowledge to create something that shouldn't even be possible.

Linking to this Twitter thread because I am not one of those "people who even kinda understand," and some of the other tweets provide useful context.