diff --git a/notes/audio.txt b/notes/audio.txt
new file mode 100644
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--- /dev/null
+++ b/notes/audio.txt
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+Game Boy audio register descriptions
+
+
+       NR_0             NR_1             NR_2             NR_3             NR_4              addresses
+       7 6 5 4 3 2 1 0  7 6 5 4 3 2 1 0  7 6 5 4 3 2 1 0  7 6 5 4 3 2 1 0  7 6 5 4 3 2 1 0
+NR1_:  _ P P P D I I I  d d L L L L L L  V V V V E p p p  l l l l l l l l  T e _ _ _ h h h   0x10..0x15
+NR2_:  _ _ _ _ _ _ _ _  d d L L L L L L  V V V V E p p p  l l l l l l l l  T e _ _ _ h h h   0x15..0x1a
+NR3_:  A _ _ _ _ _ _ _  L L L L L L L L  _ V V _ _ _ _ _  l l l l l l l l  T e _ _ _ h h h   0x1a..0x20
+NR4_:  _ _ _ _ _ _ _ _  _ _ L L L L L L  V V V V E p p p  S S S S W c c c  T e _ _ _ _ _ _   0x20..0x25
+
+Comb:  A P P P D I I I  L L L L L L L L  V V V V E p p p  l l l l l l l l  T e _ _ _ h h h
+                        d d                               S S S S W c c c
+
+Key:
+
+A: DAC Enable
+P: Sweep Pace
+D: Sweep Direction
+I: Sweep Individual step
+
+d: Duty Cycle
+L: Length Timer Initialization Value
+
+V: Envelope Volume Initialization Value
+E: Envelope Direction
+p: Envelope Pace
+
+l: Period Low Byte
+S: Clock Shift
+W: LFSR Width
+c: Clock Divider
+
+T: Trigger
+e: Length Enable
+h: Period High Bits
+
+
+Analog Pipeline Control Registers:
+       NR_0             NR_1             NR_2             NR_3             NR_4
+       7 6 5 4 3 2 1 0  7 6 5 4 3 2 1 0  7 6 5 4 3 2 1 0  7 6 5 4 3 2 1 0  7 6 5 4 3 2 1 0
+NR5_:  Z L L L z R R R  V W X Y v w x y  P _ _ _ A B C D
+
+Key:
+
+Zz: Channel 5 (VIN) Left and right sound panning
+
+Vv: Channel 1 Left and right sound panning
+Ww: Channel 2 Left and right sound panning
+Xx: Channel 3 Left and right sound panning
+Yy: Channel 4 Left and right sound panning
+
+P: APU power
+A: Channel 1 status
+B: Channel 2 status
+C: Channel 3 status
+D: Channel 4 status
+
+Source:
+https://gbdev.io/pandocs/Audio_Registers.html