Give some chapter outlines

book/src/02-concepts/00-index.md

@@ -1 +1,26 @@
 # Broad Concepts
+
+The GameBoy Advance sits in a middle place between the chthonic game consoles of
+the ancient past and the "small PC in a funny case" consoles of the modern age.
+
+On the one hand, yeah, you're gonna find a few strange conventions as you learn
+all the ropes.
+
+On the other, at least we're writing in Rust at all, and not having to do all
+the assembly by hand.
+
+This chapter for "concepts" has a section for each part of the GBA's hardware
+memory map, going by increasing order of base address value. The sections try to
+explain as much as possible while sticking to just the concerns you might have
+regarding that part of the memory map.
+
+For an assessment of how to wrangle all three parts of the video system (PALRAM,
+VRAM, and OAM), along with the correct IO registers, into something that shows a
+picture, you'll want the Video chapter.
+
+Similarly, the "IO Registers" part of the GBA actually controls how you interact
+with every single bit of hardware connected to the GBA. A full description of
+everything is obviously too much for just one section of the book. Instead you
+get an overview of general IO register rules and advice. Each particular
+register is described in the appropriate sections of either the Video or
+Non-Video chapters.

book/src/03-video/00-index.md

@@ -1 +1,9 @@
 # Video
+
+GBA Video starts with an IO register called the "Display Control Register", and
+then spirals out from there. You generally have to use Palette RAM (PALRAM),
+Video RAM (VRAM), Object Attribute Memory (OAM), as well as any number of other
+IO registers.
+
+They all have to work together just right, and there's a lot going on when you
+first try doing it, so try to take it very slowly as you're learning each step.

book/src/04-non-video/00-index.md

@@ -1 +1,21 @@
 # Non-Video
+
+Besides video effects the GBA still has an okay amount of stuff going on.
+
+Obviously you'll want to know how to read the user's button inputs. That can
+almost go without saying, except that I said it.
+
+Each other part can be handled in about any order you like.
+
+Using interrupts is perhaps one of the hardest things for us as Rust programmers
+due to quirks in our compilation process. Our code all gets compiled to 16-bit
+THUMB instructions, and we don't have a way to mark a function to be compiled
+using 32-bit ASM instructions instead. However, an interrupt handler _must_ be
+written in 32-bit ASM instructions for it to work. That means that we have to
+write our interrupt handler in 32-bit ASM by hand. We'll do it, but I don't
+think we'll be too happy about it.
+
+The Link Cable related stuff is also probably a little harder to test than
+anything else. Just because link cable emulation isn't always the best, and or
+you need two GBAs with two flash carts and the cable for hardware testing.
+Still, we'll try to go over it eventually.