While just the first episode has been released, The iBook Guy is creating a series of videos that explains the limitations of “oldschool” graphics. When you have just a handful of kilobytes of RAM, it is impossible to even store a full-quality frame buffer that the TV requires, which means that something will need to be thrown away.
The first video talks about adding color to frames with tiling and sprites. Using just ~1K of RAM, software developers were able to define background colors on a tile-by-tile basis. This allowed “black and white” to be an arbitrary “foreground and background” combination, which could even vary from one tile to the next as long as each tile only used two colors. This concept is expanded on to allow four colors per tile at a slight reduction in resolution. The video then goes into sprites, and how they are used for movable actors atop the tiles.
Image Credit: The iBook Guy
I don't know when Part 2 will be published, but it seems like they release about once per week.