diff --git a/TRICKS.txt b/TRICKS.txt
new file mode 100644
index 0000000..800b546
--- /dev/null
+++ b/TRICKS.txt
@@ -0,0 +1,15 @@
+This file describe tricks that are used throughout the code and might need
+explanation.
+
+or a: Equivalent to "cp 0", but results in a shorter opcode.
+
+xor a: sets A to 0 more efficiently than ld a, 0
+
+and 0xbf: Given a letter in the a-z range, changes it to its uppercase value
+if it's already uppercased, then it stays that way.
+
+Z if almost always used as a success indicator for routines. Set for success,
+Reset for failure. "xor a" (destroys A) and "cp a" (preserves A) are used to
+ensure Z is set. To ensure that it is reset, it's a bit more complicated and
+"unsetZ" routine exists for that, although that in certain circumstances,
+"inc a \ dec a" or "or a" can work.