diff --git a/src/bus/io.zig b/src/bus/io.zig
index 0fdd28b..019c59d 100644
--- a/src/bus/io.zig
+++ b/src/bus/io.zig
@@ -172,14 +172,14 @@ pub fn write(bus: *Bus, comptime T: type, address: u32, value: T) void {
             0x0400_0014 => bus.ppu.setBgOffsets(1, value),
             0x0400_0018 => bus.ppu.setBgOffsets(2, value),
             0x0400_001C => bus.ppu.setBgOffsets(3, value),
-            0x0400_0020 => log.debug("Wrote 0x{X:0>8} to BG2PA and BG2PB", .{value}),
-            0x0400_0024 => log.debug("Wrote 0x{X:0>8} to BG2PC and BG2PD", .{value}),
-            0x0400_0028 => log.debug("Wrote 0x{X:0>8} to BG2X", .{value}),
-            0x0400_002C => log.debug("Wrote 0x{X:0>8} to BG2Y", .{value}),
-            0x0400_0030 => log.debug("Wrote 0x{X:0>8} to BG3PA and BG3PB", .{value}),
-            0x0400_0034 => log.debug("Wrote 0x{X:0>8} to BG3PC and BG3PD", .{value}),
-            0x0400_0038 => log.debug("Wrote 0x{X:0>8} to BG3X", .{value}),
-            0x0400_003C => log.debug("Wrote 0x{X:0>8} to BG3Y", .{value}),
+            0x0400_0020 => bus.ppu.aff.bg[0].writePaPb(value),
+            0x0400_0024 => bus.ppu.aff.bg[0].writePcPd(value),
+            0x0400_0028 => bus.ppu.aff.bg[0].x.raw = value,
+            0x0400_002C => bus.ppu.aff.bg[0].y.raw = value,
+            0x0400_0030 => bus.ppu.aff.bg[1].writePaPb(value),
+            0x0400_0034 => bus.ppu.aff.bg[1].writePcPd(value),
+            0x0400_0038 => bus.ppu.aff.bg[1].x.raw = value,
+            0x0400_003C => bus.ppu.aff.bg[1].y.raw = value,
             0x0400_0040 => log.debug("Wrote 0x{X:0>8} to WIN0H and WIN1H", .{value}),
             0x0400_0044 => log.debug("Wrote 0x{X:0>8} to WIN0V and WIN1V", .{value}),
             0x0400_0048 => log.debug("Wrote 0x{X:0>8} to WININ and WINOUT", .{value}),
@@ -260,22 +260,22 @@ pub fn write(bus: *Bus, comptime T: type, address: u32, value: T) void {
             0x0400_001A => bus.ppu.bg[2].vofs.raw = value,
             0x0400_001C => bus.ppu.bg[3].hofs.raw = value,
             0x0400_001E => bus.ppu.bg[3].vofs.raw = value,
-            0x0400_0020 => log.debug("Wrote 0x{X:0>4} to BG2PA", .{value}),
-            0x0400_0022 => log.debug("Wrote 0x{X:0>4} to BG2PB", .{value}),
-            0x0400_0024 => log.debug("Wrote 0x{X:0>4} to BG2PC", .{value}),
-            0x0400_0026 => log.debug("Wrote 0x{X:0>4} to BG2PD", .{value}),
-            0x0400_0028 => log.debug("Wrote 0x{X:0>4} to BG2X_L", .{value}),
-            0x0400_002A => log.debug("Wrote 0x{X:0>4} to BG2X_H", .{value}),
-            0x0400_002C => log.debug("Wrote 0x{X:0>4} to BG2Y_L", .{value}),
-            0x0400_002E => log.debug("Wrote 0x{X:0>4} to BG2Y_H", .{value}),
-            0x0400_0030 => log.debug("Wrote 0x{X:0>4} to BG3PA", .{value}),
-            0x0400_0032 => log.debug("Wrote 0x{X:0>4} to BG3PB", .{value}),
-            0x0400_0034 => log.debug("Wrote 0x{X:0>4} to BG3PC", .{value}),
-            0x0400_0036 => log.debug("Wrote 0x{X:0>4} to BG3PD", .{value}),
-            0x0400_0038 => log.debug("Wrote 0x{X:0>4} to BG3X_L", .{value}),
-            0x0400_003A => log.debug("Wrote 0x{X:0>4} to BG3X_H", .{value}),
-            0x0400_003C => log.debug("Wrote 0x{X:0>4} to BG3Y_L", .{value}),
-            0x0400_003E => log.debug("Wrote 0x{X:0>4} to BG3Y_H", .{value}),
+            0x0400_0020 => bus.ppu.aff.bg[0].pa.raw = value,
+            0x0400_0022 => bus.ppu.aff.bg[0].pb.raw = value,
+            0x0400_0024 => bus.ppu.aff.bg[0].pc.raw = value,
+            0x0400_0026 => bus.ppu.aff.bg[0].pd.raw = value,
+            0x0400_0028 => bus.ppu.aff.bg[0].x.raw = bus.ppu.aff.bg[0].x.raw & 0xFFFF_0000 | value,
+            0x0400_002A => bus.ppu.aff.bg[0].x.raw = bus.ppu.aff.bg[0].x.raw & 0x0000_FFFF | (@as(u32, value) << 16),
+            0x0400_002C => bus.ppu.aff.bg[0].y.raw = bus.ppu.aff.bg[0].y.raw & 0xFFFF_0000 | value,
+            0x0400_002E => bus.ppu.aff.bg[0].y.raw = bus.ppu.aff.bg[0].y.raw & 0x0000_FFFF | (@as(u32, value) << 16),
+            0x0400_0030 => bus.ppu.aff.bg[1].pa.raw = value,
+            0x0400_0032 => bus.ppu.aff.bg[1].pb.raw = value,
+            0x0400_0034 => bus.ppu.aff.bg[1].pc.raw = value,
+            0x0400_0036 => bus.ppu.aff.bg[1].pd.raw = value,
+            0x0400_0038 => bus.ppu.aff.bg[1].x.raw = bus.ppu.aff.bg[1].x.raw & 0xFFFF_0000 | value,
+            0x0400_003A => bus.ppu.aff.bg[1].x.raw = bus.ppu.aff.bg[1].x.raw & 0x0000_FFFF | (@as(u32, value) << 16),
+            0x0400_003C => bus.ppu.aff.bg[1].y.raw = bus.ppu.aff.bg[1].y.raw & 0xFFFF_0000 | value,
+            0x0400_003E => bus.ppu.aff.bg[1].y.raw = bus.ppu.aff.bg[1].y.raw & 0x0000_FFFF | (@as(u32, value) << 16),
             0x0400_0040 => log.debug("Wrote 0x{X:0>4} to WIN0H", .{value}),
             0x0400_0042 => log.debug("Wrote 0x{X:0>4} to WIN1H", .{value}),
             0x0400_0044 => log.debug("Wrote 0x{X:0>4} to WIN0V", .{value}),
@@ -551,6 +551,20 @@ pub const BackgroundOffset = extern union {
     raw: u16,
 };
 
+pub const BackgroundRefPoint = extern union {
+    fractional: Bitfield(u32, 0, 8),
+    integer: Bitfield(u32, 8, 19),
+    sign: Bit(u32, 27),
+    raw: u32,
+};
+
+pub const BackgroundRotScaleParam = extern union {
+    fractional: Bitfield(u16, 0, 8),
+    integer: Bitfield(u16, 8, 7),
+    sign: Bit(u32, 15),
+    raw: u16,
+};
+
 /// Read / Write
 const InterruptRequest = extern union {
     vblank: Bit(u16, 0),
diff --git a/src/ppu.zig b/src/ppu.zig
index 1238dd9..06a4d4f 100644
--- a/src/ppu.zig
+++ b/src/ppu.zig
@@ -26,6 +26,7 @@ pub const Ppu = struct {
     // Registers
 
     bg: [4]Background,
+    aff: AffineBackground,
 
     dispcnt: io.DisplayControl,
     dispstat: io.DisplayStatus,
@@ -58,6 +59,7 @@ pub const Ppu = struct {
 
             // Registers
             .bg = [_]Background{Background.init()} ** 4,
+            .aff = AffineBackground.init(),
             .dispcnt = .{ .raw = 0x0000 },
             .dispstat = .{ .raw = 0x0000 },
             .vcount = .{ .raw = 0x0000 },
@@ -679,6 +681,51 @@ const Background = struct {
     }
 };
 
+const AffineBackground = struct {
+    const Self = @This();
+
+    bg: [2]AffineBackgroundRegisters,
+
+    fn init() Self {
+        return .{
+            .bg = [_]AffineBackgroundRegisters{AffineBackgroundRegisters.init()} ** 2,
+        };
+    }
+};
+
+const AffineBackgroundRegisters = struct {
+    const Self = @This();
+
+    x: io.BackgroundRefPoint,
+    y: io.BackgroundRefPoint,
+
+    pa: io.BackgroundRotScaleParam,
+    pb: io.BackgroundRotScaleParam,
+    pc: io.BackgroundRotScaleParam,
+    pd: io.BackgroundRotScaleParam,
+
+    fn init() Self {
+        return .{
+            .x = .{ .raw = 0 },
+            .y = .{ .raw = 0 },
+            .pa = .{ .raw = 0 },
+            .pb = .{ .raw = 0 },
+            .pc = .{ .raw = 0 },
+            .pd = .{ .raw = 0 },
+        };
+    }
+
+    pub fn writePaPb(self: *Self, value: u32) void {
+        self.pa.raw = @truncate(u16, value);
+        self.pb.raw = @truncate(u16, value >> 16);
+    }
+
+    pub fn writePcPd(self: *Self, value: u32) void {
+        self.pc.raw = @truncate(u16, value);
+        self.pd.raw = @truncate(u16, value >> 16);
+    }
+};
+
 const ScreenEntry = extern union {
     tile_id: Bitfield(u16, 0, 10),
     h_flip: Bit(u16, 10),