diff --git a/src/apu.cpp b/src/apu.cpp
index 72027e0..ab6b181 100644
--- a/src/apu.cpp
+++ b/src/apu.cpp
@@ -7,7 +7,7 @@
 
 #include "apu.h"
 
-APU::APU()
+APU::APU(unsigned int frequency) : ProcessingUnit(frequency)
 {
 }
 
diff --git a/src/apu.h b/src/apu.h
index 20ab650..a9fc899 100644
--- a/src/apu.h
+++ b/src/apu.h
@@ -11,6 +11,6 @@
 
 class APU : public ProcessingUnit {
 public:
-	APU();
+	APU(unsigned int frequency);
 	virtual ~APU();
 };
diff --git a/src/cpu.cpp b/src/cpu.cpp
index 6ce2bc7..a8764d5 100644
--- a/src/cpu.cpp
+++ b/src/cpu.cpp
@@ -6,11 +6,16 @@
  */
 
 #include "cpu.h"
+#include <iostream>
 
-CPU::CPU()
+CPU::CPU(unsigned int frequency) : ProcessingUnit(frequency)
 {
 }
 
 CPU::~CPU()
 {
 }
+
+void CPU::update() {
+	printf("This is an update from the CPU\n");
+}
\ No newline at end of file
diff --git a/src/cpu.h b/src/cpu.h
index 5241a9a..2244324 100644
--- a/src/cpu.h
+++ b/src/cpu.h
@@ -11,6 +11,8 @@
 
 class CPU final : public ProcessingUnit {
 public:
-	CPU();
+	CPU(unsigned int frequency);
 	virtual ~CPU();
+
+	void update() override;
 };
diff --git a/src/emu.cpp b/src/emu.cpp
index 610b192..a15e155 100644
--- a/src/emu.cpp
+++ b/src/emu.cpp
@@ -1,14 +1,21 @@
 #include "emu.h"
+#include "cpu.h"
+#include <iostream>
+
+void Emu::init(unsigned int frequency) {
+	m_frequency = frequency;
+}
 
 void Emu::update() {
 	for (auto unit : m_processing_units) {
-		if (m_cycle % int(m_frequency / unit.frequency()) == 0) {
-			unit.update();
+		if (m_cycle % (m_frequency / unit->frequency()) == 0) {
+			unit->update();
 		}
 	}
+	m_cycle++;
 }
 
-void Emu::addProcessingUnit(ProcessingUnit processing_unit) {
+void Emu::addProcessingUnit(ProcessingUnit* processing_unit) {
 	m_processing_units.push_back(processing_unit);
 }
 
diff --git a/src/emu.h b/src/emu.h
index b20b0c8..551f381 100644
--- a/src/emu.h
+++ b/src/emu.h
@@ -11,9 +11,11 @@ class Emu final : public ruc::Singleton<Emu> {
 public:
 	Emu(s) {}
 
+	void init(unsigned int frequency);
+
 	void update();
 
-	void addProcessingUnit(ProcessingUnit processing_unit);
+	void addProcessingUnit(ProcessingUnit* processing_unit);
 	void addMemorySpace(const char* name, int size);
 
 	void writeRAM(const char* memory_space, int location);
@@ -25,9 +27,9 @@ public:
 	uint8_t readROM(const char* memory_space, int location);
 
 private:
-	float m_frequency;
-	int m_cycle = 0;
+	unsigned int m_frequency;
+	unsigned int m_cycle = 0;
 
-	std::vector<ProcessingUnit> m_processing_units;
+	std::vector<ProcessingUnit*> m_processing_units;
 	std::unordered_map<const char*, std::vector<uint8_t>> m_memory_spaces;
 };
diff --git a/src/main.cpp b/src/main.cpp
index 34c9cf2..c757ee4 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1,6 +1,8 @@
 #include <cstdio>
 
 #include "emu.h"
+#include "cpu.h"
+#include "ppu.h"
 #include "ruc/timer.h"
 
 int main(int argc, char* argv[])
@@ -9,7 +11,19 @@ int main(int argc, char* argv[])
 
 	printf("%fms\n", t.elapsedNanoseconds() / 1000000.0);
 
-	Emu::the().ReadRAM(0, 0);
+	Emu::the().init(4000000);
+
+	CPU cpu(1000000);
+	PPU ppu(2000000);
+
+	Emu::the().addProcessingUnit(&cpu);
+	Emu::the().addProcessingUnit(&ppu);
+
+	Emu::the().addMemorySpace("RAM", 1024);
+
+	for(int i = 0; i < 1000; i++) {
+		Emu::the().update();
+	}
 
 	return 0;
 }
diff --git a/src/ppu.cpp b/src/ppu.cpp
index 93b3398..4a87c94 100644
--- a/src/ppu.cpp
+++ b/src/ppu.cpp
@@ -6,11 +6,16 @@
  */
 
 #include "ppu.h"
+#include <iostream>
 
-PPU ::PPU()
+PPU ::PPU(unsigned int frequency) : ProcessingUnit(frequency)
 {
 }
 
 PPU ::~PPU()
 {
 }
+
+void PPU::update() {
+	printf("ppu update\n");
+}
\ No newline at end of file
diff --git a/src/ppu.h b/src/ppu.h
index b236e8e..e051717 100644
--- a/src/ppu.h
+++ b/src/ppu.h
@@ -11,6 +11,7 @@
 
 class PPU final : public ProcessingUnit {
 public:
-	PPU();
+	PPU(unsigned int frequency);
 	virtual ~PPU();
+	virtual void update() override;
 };
diff --git a/src/processing-unit.cpp b/src/processing-unit.cpp
index 4026a82..a8dcc55 100644
--- a/src/processing-unit.cpp
+++ b/src/processing-unit.cpp
@@ -6,8 +6,9 @@
  */
 
 #include "processing-unit.h"
+#include <iostream>
 
-ProcessingUnit::ProcessingUnit(float frequency) : m_frequency(frequency)
+ProcessingUnit::ProcessingUnit(unsigned int frequency) : m_frequency(frequency)
 {
 }
 
@@ -15,6 +16,6 @@ ProcessingUnit::~ProcessingUnit()
 {
 }
 
-float ProcessingUnit::frequency() {
+unsigned int ProcessingUnit::frequency() {
 	return m_frequency;
 }
\ No newline at end of file
diff --git a/src/processing-unit.h b/src/processing-unit.h
index 97d6c11..ff00cd8 100644
--- a/src/processing-unit.h
+++ b/src/processing-unit.h
@@ -9,13 +9,13 @@
 
 class ProcessingUnit {
 public:
-	ProcessingUnit(float frequency);
+	ProcessingUnit(unsigned int frequency);
 	virtual ~ProcessingUnit();
 
-	virtual void update();
+	virtual void update() = 0;
 
-	float frequency();
+	unsigned int frequency();
 
 private:
-float m_frequency;
+unsigned int m_frequency;
 };