diff --git a/src/processor/memory/mmio/apu.rs b/src/processor/memory/mmio/apu.rs
index f3c1a7a..1a06cc5 100644
--- a/src/processor/memory/mmio/apu.rs
+++ b/src/processor/memory/mmio/apu.rs
@@ -3,6 +3,10 @@ use crate::{
     util::{get_bit, set_or_clear_bit},
 };
 
+use self::channels::{EnvelopeMode, NoiseChannel, PwmChannel, WaveChannel};
+
+mod channels;
+
 const MEM_START: usize = 0xFF10;
 const MEM_SIZE: usize = 0xFF40 - MEM_START;
 
@@ -10,36 +14,20 @@ const fn reg(a: Address) -> usize {
     (a as usize) - MEM_START
 }
 
-struct Channel {
-    enabled: bool,
-    pan_left: bool,
-    pan_right: bool,
-}
-
-impl Channel {
-    fn new(enabled: bool, pan_left: bool, pan_right: bool) -> Self {
-        Self {
-            enabled,
-            pan_left,
-            pan_right,
-        }
-    }
-}
-
 struct Channels {
-    one: Channel,
-    two: Channel,
-    three: Channel,
-    four: Channel,
+    one: PwmChannel,
+    two: PwmChannel,
+    three: WaveChannel,
+    four: NoiseChannel,
 }
 
 impl Default for Channels {
     fn default() -> Self {
         Self {
-            one: Channel::new(true, true, true),
-            two: Channel::new(false, true, true),
-            three: Channel::new(false, true, false),
-            four: Channel::new(false, true, false),
+            one: PwmChannel::new(true, true, true),
+            two: PwmChannel::new(false, true, true),
+            three: WaveChannel::new(false, true, false),
+            four: NoiseChannel::new(false, true, false),
         }
     }
 }
@@ -89,6 +77,13 @@ impl Apu {
 
     fn make_register(&self, addr: Address) -> u8 {
         match addr {
+            0xFF10 => self.channels.one.get_sweep_register(),
+            0xFF11 => self.channels.one.get_length_timer_and_duty_cycle(),
+            0xFF12 => self.channels.one.get_volume_and_envelope(),
+            0xFF14 => self.channels.one.get_control(),
+            0xFF16 => self.channels.two.get_length_timer_and_duty_cycle(),
+            0xFF17 => self.channels.two.get_volume_and_envelope(),
+            0xFF19 => self.channels.two.get_control(),
             0xFF24 => {
                 // NR50 - Master volume + VIN panning
                 let mut v = ((self.vol_left << 4) & 0b1110000) | (self.vol_right & 0b111);
@@ -129,7 +124,24 @@ impl Apu {
 
     pub fn mmio_write(&mut self, addr: Address, data: u8) {
         match addr {
-            0xFF10 => self.masked_io(reg(addr), data, 0b01111111),
+            0xFF10 => {
+                let pace = (data & 0b1110000) >> 4;
+                let mode = if get_bit(data, 3) {
+                    EnvelopeMode::Decrease
+                } else {
+                    EnvelopeMode::Increase
+                };
+                let slope = data & 0b111;
+                self.channels.one.update_sweep(pace, mode, slope);
+            }
+            0xFF11 => self.channels.one.update_length_timer_and_duty_cycle(data),
+            0xFF12 => self.channels.one.update_volume_and_envelope(data),
+            0xFF13 => self.channels.one.update_wavelength_low(data),
+            0xFF14 => self.channels.one.update_wavelength_high_and_control(data),
+            0xFF16 => self.channels.two.update_length_timer_and_duty_cycle(data),
+            0xFF17 => self.channels.two.update_volume_and_envelope(data),
+            0xFF18 => self.channels.two.update_wavelength_low(data),
+            0xFF19 => self.channels.two.update_wavelength_high_and_control(data),
             0xFF1A => self.masked_io(reg(addr), data, 0b10000000),
             0xFF1C => self.masked_io(reg(addr), data, 0b1100000),
             0xFF20 => self.masked_io(reg(addr), data, 0b111111),
diff --git a/src/processor/memory/mmio/apu/channels.rs b/src/processor/memory/mmio/apu/channels.rs
new file mode 100644
index 0000000..ae5848c
--- /dev/null
+++ b/src/processor/memory/mmio/apu/channels.rs
@@ -0,0 +1,167 @@
+use crate::util::{get_bit, set_or_clear_bit};
+
+#[derive(Clone, Copy, PartialEq)]
+pub(super) enum EnvelopeMode {
+    Increase,
+    Decrease,
+}
+
+struct Sweep {
+    pace: u8,
+    mode: EnvelopeMode,
+    slope: u8,
+}
+
+impl Default for Sweep {
+    fn default() -> Self {
+        Self {
+            pace: 0,
+            mode: EnvelopeMode::Increase,
+            slope: 0,
+        }
+    }
+}
+
+#[derive(Clone, Copy, PartialEq)]
+struct Envelope {
+    initial_volume: u8,
+    mode: EnvelopeMode,
+    rate: u8,
+}
+
+impl Default for Envelope {
+    fn default() -> Self {
+        Self {
+            initial_volume: 0xF,
+            mode: EnvelopeMode::Decrease,
+            rate: 0x3,
+        }
+    }
+}
+
+pub(super) struct PwmChannel {
+    pub(super) enabled: bool,
+    pub(super) pan_left: bool,
+    pub(super) pan_right: bool,
+    sweep: Sweep,
+    duty_cycle: u8,
+    length_enable: bool,
+    length_timer: u8,
+    envelope: Envelope,
+    queued_envelope: Envelope,
+    wavelength: u16,
+}
+
+impl PwmChannel {
+    pub(super) fn new(enabled: bool, pan_left: bool, pan_right: bool) -> Self {
+        Self {
+            enabled,
+            pan_left,
+            pan_right,
+            sweep: Sweep::default(),
+            duty_cycle: 2,
+            length_enable: false,
+            length_timer: 63,
+            envelope: Envelope::default(),
+            queued_envelope: Envelope::default(),
+            wavelength: 0x700,
+        }
+    }
+
+    fn trigger(&mut self) {
+        self.enabled = true;
+        self.envelope = self.queued_envelope;
+    }
+
+    pub(super) fn update_sweep(&mut self, pace: u8, mode: EnvelopeMode, slope: u8) {
+        self.sweep.pace = pace;
+        self.sweep.mode = mode;
+        self.sweep.slope = slope;
+    }
+
+    pub(super) fn get_sweep_register(&self) -> u8 {
+        set_or_clear_bit(
+            ((self.sweep.pace & 0b1110000) << 4) | (self.sweep.slope & 0b111),
+            3,
+            self.sweep.mode == EnvelopeMode::Decrease,
+        )
+    }
+
+    pub(super) fn update_length_timer_and_duty_cycle(&mut self, data: u8) {
+        self.length_timer = (data & 0b11000000) >> 6;
+        self.duty_cycle = data & 0b11111;
+    }
+
+    pub(super) fn get_length_timer_and_duty_cycle(&self) -> u8 {
+        ((self.duty_cycle & 0b11) << 6) | 0b11111
+    }
+
+    pub(super) fn update_volume_and_envelope(&mut self, data: u8) {
+        self.queued_envelope = Envelope {
+            initial_volume: (data & 0b11110000) >> 4,
+            mode: if (data & 0b1000) == 0b1000 {
+                EnvelopeMode::Increase
+            } else {
+                EnvelopeMode::Decrease
+            },
+            rate: data & 0b111,
+        };
+    }
+
+    pub(super) fn get_volume_and_envelope(&self) -> u8 {
+        set_or_clear_bit(
+            (self.queued_envelope.rate & 0b111)
+                | ((self.queued_envelope.initial_volume & 0b1111) << 4),
+            3,
+            self.queued_envelope.mode == EnvelopeMode::Decrease,
+        )
+    }
+
+    pub(super) fn update_wavelength_low(&mut self, data: u8) {
+        self.wavelength = (self.wavelength & 0xFF00) | (data as u16);
+    }
+
+    pub(super) fn update_wavelength_high_and_control(&mut self, data: u8) {
+        self.length_enable = get_bit(data, 6);
+        self.wavelength = (self.wavelength & 0xFF) | (((data & 0b111) as u16) << 8);
+        if get_bit(data, 7) {
+            self.trigger();
+        }
+    }
+
+    pub(super) fn get_control(&self) -> u8 {
+        set_or_clear_bit(0, 6, self.length_enable)
+    }
+}
+
+pub(super) struct WaveChannel {
+    pub(super) enabled: bool,
+    pub(super) pan_left: bool,
+    pub(super) pan_right: bool,
+}
+
+impl WaveChannel {
+    pub(super) fn new(enabled: bool, pan_left: bool, pan_right: bool) -> Self {
+        Self {
+            enabled,
+            pan_left,
+            pan_right,
+        }
+    }
+}
+
+pub(super) struct NoiseChannel {
+    pub(super) enabled: bool,
+    pub(super) pan_left: bool,
+    pub(super) pan_right: bool,
+}
+
+impl NoiseChannel {
+    pub(super) fn new(enabled: bool, pan_left: bool, pan_right: bool) -> Self {
+        Self {
+            enabled,
+            pan_left,
+            pan_right,
+        }
+    }
+}