Add basic hardware IO.

Emulator passes bios! hooray

doc/memory_map

@@ -6,7 +6,7 @@ E000 FCFF Copy of the work RAM
 FE00 FE9F OAM (Sprite Attribute Table)
 FEA0 FEFF Unused
 FF00 FF7F Hardware IO 
-FE80 FFFE High RAM
+FF80 FFFE High RAM
 FFFF FFFF Interrupt switch
 
 Hardware IO:

src/cpu.rs

@@ -32,6 +32,8 @@ fn to_u16(bytes: Box<[u8]>) -> u16 {
 
 impl CPU {
     pub fn new(interconnect: interconnect::Interconnect) -> CPU {
+        // Ugly patch ^.^
+        // interconnect.write_byte(0xFF44 as u16, 0x90);
         CPU {
             flags: 0,
             regs: [0, 0, 0, 0, 0, 0, 0],
@@ -59,7 +61,8 @@ impl CPU {
         if reg_id == 7 {
             self.regs[REG_A] = value;
         } else if reg_id == 6 {
-            panic!("(HL) not supported yet.");
+            let addr: u16 = self.get_pair_value(REG_H, REG_L);
+            self.interconnect.write_byte(addr, value);
         } else {
             self.regs[reg_id] = value;
         }
@@ -70,7 +73,8 @@ impl CPU {
         if reg_id == 7 {
             self.regs[REG_A]
         } else if reg_id == 6 {
-            panic!("(HL) not supported yet.");
+            let addr: u16 = self.get_pair_value(REG_H, REG_L);
+            self.interconnect.read_byte(addr)
         } else {
             self.regs[reg_id]
         }
@@ -83,10 +87,75 @@ impl CPU {
         match instruction {
             0x10 ... 0x17 => {
                 let reg_id = (instruction - 0x10) as usize;
-                let args = self.load_args(1);
+                let val = self.get_8bit_reg(reg_id);
-                let mut val = self.get_8bit_reg(reg_id);
+                println!("RL {}", REG_NAMES[reg_id]);
-                println!("RL {}, {}", REG_NAMES[reg_id], args[0]);
+                self.regs[REG_A].rotate_left(val as u32);
-                self.set_8bit_reg(reg_id, val.rotate_left(args[0] as u32));
+            }
+            0x40 ... 0x47 => {
+                // Test 0th bit
+                let reg_id = (instruction - 0x40) as usize;
+                let reg_content = self.get_8bit_reg(reg_id);
+                println!("BIT 0, {}", REG_NAMES[reg_id]);
+                if reg_content & (1 << 0) == 0 {
+                    self.flags |= FLAG_Z;
+                } else {
+                    self.flags &= !FLAG_Z;
+                }
+            }
+            0x48 ... 0x4F => {
+                // Test 1th bit
+                let reg_id = (instruction - 0x48) as usize;
+                let reg_content = self.get_8bit_reg(reg_id);
+                println!("BIT 1, {}", REG_NAMES[reg_id]);
+                if reg_content & (1 << 1) == 0 {
+                    self.flags |= FLAG_Z;
+                } else {
+                    self.flags &= !FLAG_Z;
+                }
+            }
+            0x50 ... 0x57 => {
+                // Test 2th bit
+                let reg_id = (instruction - 0x50) as usize;
+                let reg_content = self.get_8bit_reg(reg_id);
+                println!("BIT 2, {}", REG_NAMES[reg_id]);
+                if reg_content & (1 << 2) == 0 {
+                    self.flags |= FLAG_Z;
+                } else {
+                    self.flags &= !FLAG_Z;
+                }
+            }
+            0x58 ... 0x5F => {
+                // Test 3th bit
+                let reg_id = (instruction - 0x58) as usize;
+                let reg_content = self.get_8bit_reg(reg_id);
+                println!("BIT 3, {}", REG_NAMES[reg_id]);
+                if reg_content & (1 << 3) == 0 {
+                    self.flags |= FLAG_Z;
+                } else {
+                    self.flags &= !FLAG_Z;
+                }
+            }
+            0x60 ... 0x67 => {
+                // Test 4th bit
+                let reg_id = (instruction - 0x60) as usize;
+                let reg_content = self.get_8bit_reg(reg_id);
+                println!("BIT 4, {}", REG_NAMES[reg_id]);
+                if reg_content & (1 << 4) == 0 {
+                    self.flags |= FLAG_Z;
+                } else {
+                    self.flags &= !FLAG_Z;
+                }
+            }
+            0x68 ... 0x6F => {
+                // Test 5th bit
+                let reg_id = (instruction - 0x68) as usize;
+                let reg_content = self.get_8bit_reg(reg_id);
+                println!("BIT 5, {}", REG_NAMES[reg_id]);
+                if reg_content & (1 << 5) == 0 {
+                    self.flags |= FLAG_Z;
+                } else {
+                    self.flags &= !FLAG_Z;
+                }
             }
             0x70 ... 0x77 => {
                 // Test 6th bit
@@ -117,51 +186,151 @@ impl CPU {
     }
 
     fn get_pair_value(&self, a: usize, b: usize) -> u16 {
-        (self.regs[a] as u16) | (self.regs[b] as u16) << 8
+        (self.regs[a] as u16) << 8 | (self.regs[b] as u16)
     }
 
     fn set_pair_value(&mut self, a: usize, b: usize, value: u16) {
-        self.regs[a] = value as u8;
+        self.regs[a] = (value >> 8) as u8;
-        self.regs[b] = (value >> 8) as u8;
+        self.regs[b] = value as u8;
+    }
+
+    fn dump_stack(&self) {
+        for i in self.sp .. 0xFFFE {
+            println!("[{:#04X}]: {:#02X}", i, self.interconnect.read_byte(i));
+        }
+    }
+
+    fn reg_inc(&mut self, reg_id: usize) {
+        self.regs[reg_id] = self.regs[reg_id].wrapping_add(1);
+        if self.regs[reg_id] == 0 {
+            self.flags |= FLAG_Z;
+        }
+        self.flags &= !FLAG_N;
+    }
+
+    fn reg_dec(&mut self, reg_id: usize) {
+        self.regs[reg_id] = self.regs[reg_id].wrapping_sub(1);
+        if self.regs[reg_id] == 0 {
+            self.flags |= FLAG_Z;
+        } else {
+            self.flags &= !FLAG_Z;
+        }
+        self.flags |= FLAG_N;
     }
 
     pub fn run_instruction(&mut self) {
         let instruction = self.read_byte(self.ip);
-        print!("{:#04x}: {:#04x}: ", &self.ip, &instruction);
+        print!("{:#04x}: [SP: {:#04X}] i={:02X}. ", &self.ip, &self.sp, &instruction);
+        for i in 0 .. 6 {
+            print!("{}: {:02X} ", REG_NAMES[i], self.get_8bit_reg(i));
+        }
+        print!("A: {:02X}  ", self.regs[REG_A]);
+        print!("I: {:02X}  ", self.interconnect.read_byte(0xFFFF));
+
+        // Flags
+        print!("Z={} ", self.flags & FLAG_Z != 0);
+        print!("N={} ", self.flags & FLAG_N != 0);
+        print!("H={} ", self.flags & FLAG_H != 0);
+        print!("C={}  ", self.flags & FLAG_C != 0);
         self.ip += 1;
 
         match instruction {
+            0x04 => {
+                println!("INC B");
+                self.reg_inc(REG_B);
+            },
             0x05 => {
                 println!("DEC B");
-                self.regs[REG_B].wrapping_sub(1);
+                self.reg_dec(REG_B);
-            }
+            },
             0x06 => {
                 let args = self.load_args(1);
                 println!("LD B, {:02x}", args[0]);
                 self.regs[REG_B] = args[0];
-            }
+            },
             0x0C => {
                 println!("INC C");
-                self.regs[REG_C] += 1;
+                self.reg_inc(REG_C);
-            }
+            },
+            0x0D => {
+                println!("DEC C");
+                self.reg_dec(REG_C);
+            },
             0x0E => {
                 let args = self.load_args(1);
                 println!("LD C, {:02x}", args[0]);
                 self.regs[REG_C] = args[0];
-            }
+            },
             0x11 => {
                 let args = self.load_args(2);
-                println!("LD DE, {:02x}{:02x}", args[1], args[0]);
+                let val = to_u16(args);
+                println!("LD DE, {:04x}", val);
+                self.set_pair_value(REG_D, REG_E, val);
+            },
+            0x13 => {
+                println!("INC DE");
+                let old_value = self.get_pair_value(REG_D, REG_E);
+                self.set_pair_value(REG_D, REG_E, old_value + 1);
+            },
+            0x14 => {
+                println!("INC D");
+                self.reg_inc(REG_D);
+            },
+            0x15 => {
+                println!("DEC D");
+                self.reg_dec(REG_D);
+            },
+            0x16 => {
+                let args = self.load_args(1);
+                println!("LD D, {:02x}", args[0]);
                 self.regs[REG_D] = args[0];
-                self.regs[REG_E] = args[1];
+            },
+            0x17 => {
+                println!("RLA");
+                let carry = self.flags & FLAG_C == FLAG_C;
+                if !carry {
+                    // No carry before, now we got a carry => set it
+                    if self.regs[REG_A] & 0x80 == 0x80 {
+                        self.flags |= FLAG_C
+                    }
+                    self.regs[REG_A] = self.regs[REG_A] << 1;
+                } else {
+                    if self.regs[REG_A] & 0x80 == 0 {
+                        self.flags &= !FLAG_C;
+                    }
+                    self.regs[REG_A] = self.regs[REG_A] << 1 | 1;
+                }
+            },
+            0x18 => {
+                let args = self.load_args(1);
+                println!("JR {:02X}", args[0] as i8);
+                let off: i8 = args[0] as i8;
+                if off < 0 {
+                    self.ip -= (-off) as u16;
+                } else {
+                    self.ip += off as u16;
+                }
             },
             0x1A => {
                 println!("LD A, (DE)");
                 self.regs[REG_A] = self.interconnect.read_byte(self.get_pair_value(REG_D, REG_E));
-            }
+            },
+            0x1C => {
+                println!("INC E");
+                self.reg_inc(REG_E);
+            },
+            0x1D => {
+                println!("DEC E");
+                self.reg_dec(REG_E);
+            },
+            0x1E => {
+                let args = self.load_args(1);
+                println!("LD E, {:02x}", args[0]);
+                self.regs[REG_E] = args[0];
+            },
             0x20 => {
                 let args = self.load_args(1);
-                println!("JR NZ {:02x}", args[0]);
+                println!("JR NZ {:02x}", args[0] as i8);
                 if self.flags & FLAG_Z == 0 {
                     let offset = args[0] as i8;
                     if offset < 0 {
@@ -172,16 +341,58 @@ impl CPU {
                 }
             }
             0x21 => {
-                let args = self.load_args(2);
+                let value = to_u16(self.load_args(2));
-                println!("LD HL, {:02x}{:02x}", args[1], args[0]);
+                println!("LD HL, {:04x}", value);
-                self.regs[REG_H] = args[0];
+                self.set_pair_value(REG_H, REG_L, value);
-                self.regs[REG_L] = args[1];
+            },
+            0x22 => {
+                println!("LD (HL+), A");
+                let addr: u16 = self.get_pair_value(REG_H, REG_L);
+                self.interconnect.write_byte(addr, self.regs[REG_A]);
+                self.set_pair_value(REG_H, REG_L, addr + 1);
+            },
+            0x23 => {
+                println!("INC HL");
+                let old_value = self.get_pair_value(REG_H, REG_L);
+                self.set_pair_value(REG_H, REG_L, old_value + 1);
+            },
+            0x24 => {
+                println!("INC H");
+                self.reg_inc(REG_H);
+            },
+            0x25 => {
+                println!("DEC H");
+                self.reg_dec(REG_H);
             },
             0x26 => {
                 let args = self.load_args(1);
                 println!("LD H, {:02x}", args[0]);
                 self.regs[REG_H] = args[0];
             },
+            0x28 => {
+                let args = self.load_args(1);
+                let mut target;
+                if args[0] < 0 {
+                    target = self.ip - (-(args[0] as i8)) as u16;
+                } else {
+                    target = self.ip + args[0] as u16;
+                }
+                println!("LR Z, {:04X}", target);
+                self.ip = target;
+            },
+            0x2C => {
+                println!("INC L");
+                self.reg_inc(REG_L);
+            },
+            0x2D => {
+                println!("DEC L");
+                self.reg_dec(REG_L);
+            },
+            0x2E => {
+                let args = self.load_args(1);
+                println!("LD L, {:02x}", args[0]);
+                self.regs[REG_L] = args[0];
+            },
             0x31 => {
                 let args = self.load_args(2);
                 self.sp = to_u16(args);
@@ -189,18 +400,33 @@ impl CPU {
             },
             0x32 => {
                 println!("LD (HL-), A");
-                let mut addr: u16 = (self.regs[REG_H] as u16) | ((self.regs[REG_L] as u16) << 8);
+                let mut addr = self.get_pair_value(REG_H, REG_L);
                 self.interconnect.write_byte(addr, self.regs[REG_A]);
 
                 addr -= 1;
-                self.regs[REG_H] = addr as u8;
+                self.set_pair_value(REG_H, REG_L, addr);
-                self.regs[REG_L] = (addr >> 8) as u8;
             },
+            0x36 => {
+                let args = self.load_args(1);
+                println!("LD (HL), {:02x}", args[0]);
+                let addr = self.get_pair_value(REG_H, REG_L);
+                self.interconnect.write_byte(addr, args[0]);
+            },
+            0x3C => {
+                println!("INC A");
+                self.reg_inc(REG_A);
+            }
+            0x3D => {
+                println!("DEC A");
+                self.reg_dec(REG_A);
+            }
             0x3E => {
                 let args = self.load_args(1);
                 println!("LD A, {:02x}", args[0]);
                 self.regs[REG_A] = args[0];
             },
+
+            // LDs
             0x40 ... 0x47 => {
                 let reg_id = (instruction - 0x40) as usize;
                 println!("LD B, {}", REG_NAMES[reg_id]);
@@ -235,7 +461,7 @@ impl CPU {
                 let reg_id = (instruction - 0x70) as usize;
                 println!("LD (HL), {}", REG_NAMES[reg_id]);
                 let reg_value: u8 = self.get_8bit_reg(reg_id);
-                let addr: u16 = (self.regs[REG_L] as u16) << 8 | (self.regs[REG_H] as u16);
+                let addr: u16 = self.get_pair_value(REG_H, REG_L);
  
                 self.interconnect.write_byte(addr, reg_value);
             },
@@ -244,10 +470,81 @@ impl CPU {
                 println!("LD A, {}", REG_NAMES[reg_id]);
                 self.regs[REG_A] = self.get_8bit_reg(reg_id);
             },
+
+            // ADD
+            0x80 ... 0x87 => {
+                let reg_id = (instruction - 0x80) as usize;
+                println!("ADD {}", REG_NAMES[reg_id]);
+                self.regs[REG_A] = self.regs[REG_A].wrapping_add(self.get_8bit_reg(reg_id));
+                self.flags &= !FLAG_N;
+            }
+
+            // ADC
+            0x88 ... 0x8F => {
+                let reg_id = (instruction - 0x88) as usize;
+                println!("ADC {}", REG_NAMES[reg_id]);
+                self.regs[REG_A] = self.regs[REG_A].wrapping_add(self.get_8bit_reg(reg_id));
+                if self.flags & FLAG_C == FLAG_C {
+                    self.regs[REG_A] = self.regs[REG_A].wrapping_add(1);
+                }
+                self.flags &= !FLAG_N;
+            }
+
+            // SUBs
+            0x90 ... 0x97 => {
+                let reg_id = (instruction - 0x90) as usize;
+                println!("SUB {}", REG_NAMES[reg_id]);
+                self.regs[REG_A] = self.regs[REG_A].wrapping_sub(self.get_8bit_reg(reg_id));
+                self.flags |= FLAG_N;
+                if self.regs[REG_A] == 0 {
+                    self.flags |= FLAG_Z;
+                } else {
+                    self.flags &= !FLAG_Z;
+                }
+                // TODO: H, C
+            }
+
+            // SBC
+            0x98 ... 0x9F => {
+                let reg_id = (instruction - 0x98) as usize;
+                println!("SBC {}", REG_NAMES[reg_id]);
+                self.regs[REG_A] = self.regs[REG_A].wrapping_sub(self.get_8bit_reg(reg_id));
+                if self.flags & FLAG_C == FLAG_C {
+                    self.regs[REG_A] = self.regs[REG_A].wrapping_sub(1);
+                }
+                self.flags |= FLAG_N;
+            }
+
+            // XOR
             0xA8 ... 0xAF => {
                 let reg_id = (instruction - 0xA8) as usize;
                 println!("XOR {}", REG_NAMES[reg_id]);
                 self.regs[REG_A] ^= self.get_8bit_reg(reg_id);
+                if self.regs[REG_A] == 0 {
+                    self.flags |= FLAG_Z;
+                } else {
+                    self.flags &= !FLAG_Z;
+                }
+                self.flags &= !FLAG_C;
+                self.flags &= !FLAG_N;
+                self.flags &= !FLAG_H;
+            },
+
+            // CP
+            0xB8 ... 0xBF => {
+                let reg_id = (instruction - 0xB8) as usize;
+                println!("CP {}", REG_NAMES[reg_id]);
+                let val = self.get_8bit_reg(reg_id);
+                if self.regs[REG_A] < self.get_8bit_reg(reg_id) {
+                    self.flags |= FLAG_C;
+                    self.flags &= !FLAG_Z;
+                } else if self.regs[REG_A] == self.get_8bit_reg(reg_id) {
+                    self.flags |= FLAG_Z;
+                    self.flags &= !FLAG_C;
+                } else {
+                    self.flags &= !FLAG_Z;
+                    self.flags &= !FLAG_C;
+                }
             },
             0xC1 => {
                 println!("POP BC");
@@ -258,9 +555,15 @@ impl CPU {
             0xC5 => {
                 println!("PUSH BC");
                 let val: u16 = self.get_pair_value(REG_B, REG_C);
-                self.interconnect.write_word(self.sp, val);
+                self.interconnect.write_word(self.sp - 2, val);
                 self.sp -= 2;
             },
+            0xC9 => {
+                println!("RET");
+                self.dump_stack();
+                self.ip = self.interconnect.read_word(self.sp+1);
+                self.sp += 2;
+            },
             0xCB => {
                 // Prefix CB. This is annoying.
                 self.run_prefix_instruction();
@@ -273,23 +576,56 @@ impl CPU {
                 // self.interconnect.write_byte(self.sp - 1, (self.ip >> 8) as u8);
                 self.interconnect.write_word(self.sp - 1, self.ip);
                 self.sp -= 2;
+                self.dump_stack();
 
                 self.ip = target;
-            }
+            },
             0xE0 => {
                 let args = self.load_args(1);
                 println!("LDH {:02X}, A", args[0]);
                 self.interconnect.write_byte(0xFF00 + args[0] as u16, self.regs[REG_A]);
-            }
+            },
             0xE2 => {
                 println!("LD (C), A");
+                println!("[{:04X}] = {:02X}", 0xFF00 + self.regs[REG_C] as u16, self.regs[REG_A]);
                 self.interconnect.write_byte(0xFF00 + self.regs[REG_C] as u16, self.regs[REG_A])
+            },
+            0xEA => {
+                let addr = to_u16(self.load_args(2));
+                println!("LD ({:04X}), A", addr);
+                self.interconnect.write_byte(addr, self.regs[REG_A]);
             }
+            0xF0 => {
+                let args = self.load_args(1);
+                println!("LDH A, {:02X}", args[0]);
+                self.regs[REG_A] = self.interconnect.read_byte(0xFF00 + args[0] as u16);
+            },
             0xFB => {
                 // Enable interrupts - TODO
                 println!("EI");
+                self.interconnect.write_byte(0xFFFF, 0x01);
+                panic!("Uh uh");
+            },
+            0xFE => {
+                let args = self.load_args(1);
+                println!("CP {:02X}", args[0]);
+                self.flags |= FLAG_N;
+                if args[0] > self.regs[REG_A] {
+                    self.flags |= FLAG_C;
+                } else {
+                    self.flags &= !FLAG_C;
+                }
+                if args[0] == self.regs[REG_A] {
+                    self.flags |= FLAG_Z;
+                } else {
+                    self.flags &= !FLAG_Z;
+                }
+
+                // TODO H
             }
             _ => panic!("Unknown instruction: {:02x}", instruction)
         }
+        // self.dump_stack();
+        self.interconnect.tick();
     }
 }

src/display.rs

@@ -0,0 +1,51 @@
+#[derive(Debug, Default)]
+pub struct Display {
+    control: u8,
+    status: u8,
+    background_palette: u8,
+    scrollx: u8,
+    scrolly: u8,
+    curline: u8,
+    // TODO
+}
+
+impl Display {
+    pub fn new() -> Display {
+        Display::default()
+    }
+
+    pub fn write_byte(&mut self, addr: u16, val: u8) {
+        match addr {
+            0xFF40 => self.control = val,
+            0xFF41 => self.status = val,
+            0xFF42 => self.scrolly = val,
+            0xFF43 => self.scrollx = val,
+            0xFF44 => self.curline = 0,
+            0xFF47 => self.background_palette = val,
+            _ => panic!("Display: Write {:02X} to {:04X} unsupported", val, addr),
+        }
+    }
+
+    pub fn read_byte(&self, addr: u16) -> u8 {
+        match addr {
+            0xFF40 => self.control,
+            0xFF41 => self.status,
+            0xFF42 => self.scrolly,
+            0xFF43 => self.scrollx,
+            0xFF44 => self.curline,
+            0xFF47 => self.background_palette,
+            _ => panic!("Display: Read from {:04X} unsupported", addr),
+        }
+    }
+
+    pub fn vblank_interrupt(&mut self) {
+        self.curline += 1;
+        if self.curline > 153 {
+            self.curline = 0;
+        }
+    }
+
+    pub fn controller_interrupt(&self) {
+        
+    }
+}

src/interconnect.rs

@@ -1,13 +1,24 @@
 const RAM_SIZE: usize = 0x2000;
 const VRAM_SIZE: usize = 0x2000;
-const HIRAM_SIZE: usize = (0xFFFE - 0xFE80) + 1;
+const HIRAM_SIZE: usize = (0xFFFE - 0xFF80) + 1;
+
+const INTERRUPT_DISPLAY: u8 = 1 << 1;
+const INTERRUPT_DISPLAY_VBLANK: u8 = 1 << 0;
+
+use super::display;
+use super::sound;
 
 pub struct Interconnect {
     bios: Box<[u8]>,
     rom: Box<[u8]>,
     ram: Box<[u8]>,
     vram: Box<[u8]>,
-    hiram: Box<[u8]>
+    hiram: Box<[u8]>,
+    sound: sound::Sound,
+    display: display::Display,
+    interrupt: u8,
+    timer: u8,
+    disable_bootrom: u8,
 }
 
 impl Interconnect {
@@ -18,6 +29,32 @@ impl Interconnect {
             ram: vec![0; RAM_SIZE].into_boxed_slice(),
             vram: vec![0; VRAM_SIZE].into_boxed_slice(),
             hiram: vec![0; HIRAM_SIZE].into_boxed_slice(),
+            sound: sound::Sound::new(),
+            display: display::Display::new(),
+            interrupt: 0,
+            timer: 0,
+            disable_bootrom: 0,
+        }
+    }
+
+    // Somehow we need different timers for this.
+    pub fn tick(&mut self) {
+        self.timer += 1;
+        if self.timer == 5 {
+            self.display_blank_interrupt();
+            self.timer = 0;
+        }
+    }
+
+    pub fn display_blank_interrupt(&mut self) {
+        if self.interrupt & INTERRUPT_DISPLAY_VBLANK >= 0 {
+            self.display.vblank_interrupt();
+        }
+    }
+
+    pub fn display_interrupt(&mut self) {
+        if self.interrupt & INTERRUPT_DISPLAY > 0 {
+            self.display.controller_interrupt();
         }
     }
 
@@ -28,7 +65,7 @@ impl Interconnect {
         match addr {
             0x0000 ... 0x7FFF => {
                 // TODO: Check if bios or cartridge (additional condition: isEnabled)
-                if addr < 0x100 {
+                if addr < 0x100 && self.disable_bootrom == 0 {
                     self.bios[addr as usize]
                 } else {
                     self.rom[addr as usize]
@@ -40,8 +77,20 @@ impl Interconnect {
             0xC000 ... 0xDFFF => {
                 self.ram[(addr - 0xC000) as usize]
             },
-            0xFE80 ... 0xFFFE => {
+            0xFF10 ... 0xFF26 => {
-                self.hiram[(addr - 0xFE80) as usize]
+                self.sound.read_byte(addr)
+            },
+            0xFF40 ... 0xFF4B => {
+                self.display.read_byte(addr)
+            },
+            0xFF50 => {
+                self.disable_bootrom
+            },
+            0xFF80 ... 0xFFFE => {
+                self.hiram[(addr - 0xFF80) as usize]
+            },
+            0xFFFF => {
+                self.interrupt
             }
             _ => {
                 panic!("Read from {:04X} not supported.", addr);
@@ -61,7 +110,7 @@ impl Interconnect {
         FE00 FE9F OAM (Sprite Attribute Table)
         FEA0 FEFF Unused
         FF00 FF7F Hardware IO 
-        FE80 FFFE High RAM
+        FF80 FFFE High RAM
         FFFF FFFF Interrupt switch
         */
 
@@ -72,9 +121,21 @@ impl Interconnect {
             0xC000 ... 0xDFFF => {
                 self.ram[(addr - 0xC000) as usize] = val;
             },
-            0xFE80 ... 0xFFFE => {
+            0xFF10 ... 0xFF26 => {
-                self.hiram[(addr - 0xFE80) as usize] = val;
+                self.sound.write_byte(addr, val);
+            },
+            0xFF40 ... 0xFF4B => {
+                self.display.write_byte(addr, val);
+            },
+            0xFF50 => {
+                self.disable_bootrom = val;
             }
+            0xFF80 ... 0xFFFE => {
+                self.hiram[(addr - 0xFF80) as usize] = val;
+            },
+            0xFFFF => {
+                self.interrupt = val;
+            },
             _ => {
                 panic!("Write {:02X} to {:04X} not supported.", val, addr);
             }

src/main.rs

@@ -7,7 +7,10 @@ use std::fs;
 use std::env;
 
 mod cpu;
+mod display;
 mod interconnect;
+mod sound;
+
 
 fn main() {
     let bios_path = env::args().nth(1).unwrap();
@@ -16,11 +19,11 @@ fn main() {
     let rom = read_rom(&rom_path);
 
     // Now we need to execute commands
-    let mut interconnect = interconnect::Interconnect::new(bios, rom);
+    let interconnect = interconnect::Interconnect::new(bios, rom);
-    let mut CPU = cpu::CPU::new(interconnect);
+    let mut cpu = cpu::CPU::new(interconnect);
 
     loop {
-        CPU.run_instruction();
+        cpu.run_instruction();
     }
 }
 

src/sound.rs

@@ -0,0 +1,42 @@
+#[derive(Debug, Default)]
+pub struct Sound {
+    enabled: u8,
+    sound_length_1: u8,
+    sound_control_1: u8,
+    sound_channel_volume_control: u8,
+    sound_output_terminal_selector: u8,
+    sound_freq_low: u8,
+    sound_freq_high: u8,
+}
+
+impl Sound {
+    pub fn new() -> Sound {
+        Sound::default()
+    }
+
+    pub fn write_byte(&mut self, addr: u16, val: u8) {
+        match addr {
+            0xFF11 => self.sound_length_1 = val,
+            0xFF12 => self.sound_control_1 = val,
+            0xFF13 => self.sound_freq_low = val,
+            0xFF14 => self.sound_freq_high = val,
+            0xFF24 => self.sound_channel_volume_control = val,
+            0xFF25 => self.sound_output_terminal_selector = val,
+            0xFF26 => self.enabled = val,
+            _ => panic!("Sound: Write {:02X} to {:04X} unsupported", val, addr),
+        }
+    }
+
+    pub fn read_byte(&self, addr: u16) -> u8 {
+        match addr {
+            0xFF11 => self.sound_length_1,
+            0xFF12 => self.sound_control_1,
+            0xFF13 => self.sound_freq_low,
+            0xFF14 => self.sound_freq_high,
+            0xFF24 => self.sound_channel_volume_control,
+            0xFF25 => self.sound_output_terminal_selector,
+            0xFF26 => self.enabled,
+            _ => panic!("Sound: Read from {:04X} unsupported", addr),
+        }
+    }
+}