1 files changed, 24 insertions, 0 deletions
diff --git a/scroll/README.md b/scroll/README.md
new file mode 100644
index 0000000..553a497
--- /dev/null
+++ b/scroll/README.md
@@ -0,0 +1,24 @@
+## Scrolling
+
+Scrolling is a big topic and it's something that evolved with the NES hardware.
+This set of examples try to cover it as much as possible while being
+approachable as single files.
+
+First of all, you should take a look at `level.s`, which shows how games can
+scroll a level and continuously load/unload the next/previous sections of the
+level.
+
+The second example is `sprite0.s`, which covers the scrolling done by games such
+as Super Mario Bros. or Punch-out. That is, we use the "sprite 0 hit" detection
+to keep the top level part of the screen from moving (so to show relevant
+information), while allowing the rest of the screen to scroll as expected. In
+the end, it's the same example as `level.s` (same level to scroll), but the top
+part does not move and shows a "THIS DOES NOT MOVE" message.
+
+Last but not least, the `mmc3.s` example shows how to configure the MMC3 chip
+(e.g. Super Mario Bros. 3, Kirby's Adventure) to have better control on which
+parts of the screen to scroll or not. To showcase this the example implements a
+Pong game by scrolling the paddles instead of directly setting their positions.
+This is probably the most stupid way to use this hardware expansion (kind of
+like killing a fly with a cannon), but it at least shows a simple way to have
+two independent scrolls while having a static middle ground.