diff --git a/src/addressSpace.hpp b/src/addressSpace.hpp
index f4f9ba0..d7e2c8f 100644
--- a/src/addressSpace.hpp
+++ b/src/addressSpace.hpp
@@ -43,7 +43,6 @@ public:
     Byte TAC = 0xF8;
     // interrupt flag and enable
     Byte IF = 0xE1;
-    ;
     // Sound registers
     Byte NR10;
     Byte NR11;
@@ -103,7 +102,7 @@ public:
   void loadRomBank();
   void createRamBank();
   void loadRamBank();
-  MBCType MBC = {};
+  MBCType_enum MBC = {};
   uint32_t romSize = 0;
   uint32_t romBanks = 0;
   uint32_t externalRamSize = 0;
@@ -116,7 +115,8 @@ public:
   // Selected ROM Bank in MBC1 = (Secondary Bank << 5) + ROM Bank
   Byte selectedRomBank = 0;
   Byte romBankRegister = 0x00;
-  // 2 bit register acts as secondary rom bank register or ram bank number in MBC1
+  // 2 bit register acts as secondary rom bank register or ram bank number in
+  // MBC1
   Byte twoBitBankRegister = 0x0;
   Byte selectedExternalRamBank = 0;
   Byte romRamSelect = 0x00;
@@ -128,6 +128,13 @@ public:
   // MBC3
   Byte latchClockData = 0x00;
   Byte ramBankRTCRegister = 0x00;
+  // RTC registers
+  enabledRTCRegister_enum enabledRTCRegister = NONE;
+  Byte RTCSeconds = 0x0;
+  Byte RTCMinutes = 0x0;
+  Byte RTCHours = 0x0;
+  Byte RTCDayLower = 0x0;
+  Byte RTCDayHigher = 0x0;
 
   void setTesting(bool state);
 
@@ -144,6 +151,20 @@ public:
     else if (address < 0xA000)
       return memoryLayout.vram[address - 0x8000];
     else if (address < 0xC000) {
+      if (enabledRTCRegister != NONE) {
+        switch (enabledRTCRegister) {
+        case RTCS:
+          return RTCSeconds;
+        case RTCM:
+          return RTCMinutes;
+        case RTCH:
+          return RTCHours;
+        case RTCDL:
+          return RTCDayLower;
+        case RTCDH:
+          return RTCDayHigher;
+        }
+      }
       if (externalRamSize == 0)
         return 0xFF;
       // MBC2 echos 15 times and only stores lower 4 bits
diff --git a/src/defines.hpp b/src/defines.hpp
index f6eaca5..0a00d6a 100644
--- a/src/defines.hpp
+++ b/src/defines.hpp
@@ -79,7 +79,7 @@ struct Input {
   bool SELECT = false;
 };
 
-enum MBCType {
+enum MBCType_enum {
   romOnly = 0x00,
   MBC1 = 0x01,
   MBC1Ram = 0x02,
@@ -111,7 +111,7 @@ enum MBCType {
   HuC1RamBattery = 0xFF
 };
 
-enum PPUMode {
+enum PPUMode_enum {
   mode0, // Horizontal Blank (Mode 0): No access to video RAM, occurs during
          // horizontal blanking period.
   mode1, // Vertical Blank (Mode 1): No access to video RAM, occurs during
@@ -122,4 +122,12 @@ enum PPUMode {
          // pixel transfer to the screen.
 };
 
+enum enabledRTCRegister_enum {
+  NONE = 0x00,
+  RTCS = 0x08,
+  RTCM = 0x09,
+  RTCH = 0x0A,
+  RTCDL = 0x0B,
+  RTCDH = 0x0C
+};
 #endif
diff --git a/src/gameboy.hpp b/src/gameboy.hpp
index 2c81ab5..8b4003e 100644
--- a/src/gameboy.hpp
+++ b/src/gameboy.hpp
@@ -50,7 +50,7 @@ class GameBoy {
   AddressSpace addressSpace;
   const AddressSpace &readOnlyAddressSpace = addressSpace;
 
-  PPUMode currentMode = PPUMode::mode0;
+  PPUMode_enum currentMode = PPUMode_enum::mode0;
   Byte windowLineCounter = 0;
   int16_t cyclesUntilDMATransfer = 160;
 
@@ -86,7 +86,7 @@ class GameBoy {
   void SDL2present();
 
   void checkPPUMode();
-  void setPPUMode(PPUMode mode);
+  void setPPUMode(PPUMode_enum mode);
   uint64_t cyclesSinceLastScanline() const;
   uint64_t cyclesSinceLastRefresh() const;
 
diff --git a/src/mbc.cpp b/src/mbc.cpp
index 248466f..4b59c46 100644
--- a/src/mbc.cpp
+++ b/src/mbc.cpp
@@ -1,7 +1,8 @@
 #include "addressSpace.hpp"
+#include "defines.hpp"
 
 void AddressSpace::determineMBCInfo() {
-  MBC = static_cast<MBCType>(memoryLayout.romBank0[0x147]);
+  MBC = static_cast<MBCType_enum>(memoryLayout.romBank0[0x147]);
   romSize = 32768 * (1 << memoryLayout.romBank0[0x147]);
   romBanks = 1 << (memoryLayout.romBank0[0x147] + 1);
 
@@ -130,17 +131,33 @@ void AddressSpace::MBCUpdate() {
     loadRamBank();
   } else if (MBC == MBC2 || MBC == MBC2Battery) {
     selectedRomBank = romBankRegister & 0x0F;
+    selectedExternalRamBank = 0;
+
     loadRomBank();
     loadRamBank();
   } else if (MBC == MBC3 || MBC == MBC3TimerBattery) {
     selectedRomBank = romBankRegister & 0x7F;
+    selectedExternalRamBank = 0;
 
+    if (MBC == MBC3TimerBattery) {
+      if(ramBankRTCRegister >= 0x8 && ramBankRTCRegister <= 0xC)
+        enabledRTCRegister = static_cast<enabledRTCRegister_enum>(ramBankRTCRegister);
+      else
+        enabledRTCRegister = NONE;
+    }
     loadRomBank();
     loadRamBank();
   } else if (MBC == MBC3Ram || MBC == MBC3RamBattery ||
              MBC == MBC3TimerRamBattery) {
     selectedRomBank = romBankRegister & 0x7F;
+    selectedExternalRamBank = ramBankRTCRegister & 0b11;
 
+    if (MBC == MBC3TimerRamBattery) {
+      if(ramBankRTCRegister >= 0x8 && ramBankRTCRegister <= 0xC)
+        enabledRTCRegister = static_cast<enabledRTCRegister_enum>(ramBankRTCRegister);
+      else
+        enabledRTCRegister = NONE;
+    }
     loadRomBank();
     loadRamBank();
   }
diff --git a/src/ppu.cpp b/src/ppu.cpp
index db74d63..f84ae2e 100644
--- a/src/ppu.cpp
+++ b/src/ppu.cpp
@@ -46,9 +46,9 @@ void GameBoy::ppuUpdate() {
       readOnlyAddressSpace.memoryLayout.STAT & (1 << 5);
   const bool previousInterruptLine = statInteruptLine;
 
-  if (currentMode == PPUMode::mode0 && hBlankInterruptEnabled ||
-      currentMode == PPUMode::mode3 && drawingInterruptEnabled ||
-      currentMode == PPUMode::mode2 && oamInterruptEnabled) {
+  if (currentMode == PPUMode_enum::mode0 && hBlankInterruptEnabled ||
+      currentMode == PPUMode_enum::mode3 && drawingInterruptEnabled ||
+      currentMode == PPUMode_enum::mode2 && oamInterruptEnabled) {
     statInteruptLine = true;
   } else {
     statInteruptLine = false;
@@ -84,13 +84,13 @@ void GameBoy::checkPPUMode() {
     break;
   case 2:
     if (cyclesSinceScanline > MODE2_DURATION) {
-      setPPUMode(PPUMode::mode3);
+      setPPUMode(PPUMode_enum::mode3);
     }
     break;
   case 3:
     if (cyclesSinceScanline > MODE2_DURATION + MODE3_MIN_DURATION) {
       drawLine();
-      setPPUMode(PPUMode::mode0);
+      setPPUMode(PPUMode_enum::mode0);
     }
     break;
   }
@@ -98,14 +98,14 @@ void GameBoy::checkPPUMode() {
 
 void GameBoy::incLY() {
   addressSpace.memoryLayout.LY += 1;
-  setPPUMode(PPUMode::mode2);
+  setPPUMode(PPUMode_enum::mode2);
   if (addressSpace.memoryLayout.LY > SCANLINES_PER_FRAME - 1) {
     addressSpace.memoryLayout.LY = 0;
     windowLineCounter = 0;
   } else if (addressSpace.memoryLayout.LY == 144) {
     // VBlank Period
     SDL2present();
-    setPPUMode(PPUMode::mode1);
+    setPPUMode(PPUMode_enum::mode1);
     addressSpace.memoryLayout.IF |= 0x1;
   }
 }
@@ -120,7 +120,7 @@ uint64_t GameBoy::cyclesSinceLastRefresh() const {
   return difference;
 }
 
-void GameBoy::setPPUMode(const PPUMode mode) {
+void GameBoy::setPPUMode(const PPUMode_enum mode) {
   switch (mode) {
   case mode0:
     addressSpace.memoryLayout.STAT &= ~0x03;