diff --git a/kernel/arch/x86_64/architecture/cpu.d b/kernel/arch/x86_64/architecture/cpu.d
index 9d90a47..fdf56a2 100644
--- a/kernel/arch/x86_64/architecture/cpu.d
+++ b/kernel/arch/x86_64/architecture/cpu.d
@@ -109,6 +109,32 @@ public:
 		}`;
 	}
 
+	void ioOut(T)(int port, int data) {
+		asm {
+			mov EAX, data;
+			mov EDX, port;
+		}
+
+		static if (is(T == ubyte) || is(T == byte)) {
+			asm {
+				out DX, AL;
+			}
+		}
+		else static if (is(T == ushort) || is(T == short)) {
+			asm {
+				out DX, AX;
+			}
+		}
+		else static if (is(T == uint) || is(T == int)) {
+			asm {
+				out DX, EAX;
+			}
+		}
+		else {
+			static assert (false, "Cannot determine data type.");
+		}
+	}
+
 	void ioOut(T, char[] port)(int data) {
 		//static assert (port[$-1] == 'h', "Cannot reduce port number");
 
diff --git a/kernel/arch/x86_64/architecture/pci.d b/kernel/arch/x86_64/architecture/pci.d
index c604092..7941535 100644
--- a/kernel/arch/x86_64/architecture/pci.d
+++ b/kernel/arch/x86_64/architecture/pci.d
@@ -13,6 +13,7 @@ class PCIImplementation {
 static:
 
 	// Description: Will read a uint from PCI.
+	synchronized
 	uint read32(uint address) {
 		_setAddress(address);
 
@@ -24,6 +25,7 @@ static:
 	}
 
 	// Description: Will read a ushort from PCI.
+	synchronized
 	ushort read16(uint address) {
 		_setAddress(address);
 
@@ -35,6 +37,7 @@ static:
 	}
 
 	// Description: Will read a ubyte from PCI.
+	synchronized
 	ubyte read8(uint address) {
 		_setAddress(address);
 
@@ -46,18 +49,43 @@ static:
 	}
 
 	// Description: Will write to PCI.
-	void write8(uint address, ubyte value) {
+	synchronized
+	void write32(uint address, uint value) {
+		_setAddress(address);
+
+		// get offset
+		ushort offset = cast(ushort)(address & 0xff);
+
+		// write in data
+		Cpu.ioOut!(uint)(0xcfc + offset, value);
 	}
 
 	// Description: Will write to PCI.
+	synchronized
 	void write16(uint address, ushort value) {
+		_setAddress(address);
+
+		// get offset
+		ushort offset = cast(ushort)(address & 0xff);
+
+		// write in data
+		Cpu.ioOut!(ushort)(0xcfc + offset, value);
 	}
 
 	// Description: Will write to PCI.
-	void write32(uint address, uint value) {
+	synchronized
+	void write8(uint address, ubyte value) {
+		_setAddress(address);
+
+		// get offset
+		ushort offset = cast(ushort)(address & 0xff);
+
+		// write in data
+		Cpu.ioOut!(ubyte)(0xcfc + offset, value);
 	}
 
 private:
+
 	void _setAddress(uint address) {
 		// write out address
 		Cpu.ioOut!(uint, "0xcf8")(address);