diff --git a/Cart_Reader/SMS.ino b/Cart_Reader/SMS.ino
index a8b8b3c..7c093d8 100644
--- a/Cart_Reader/SMS.ino
+++ b/Cart_Reader/SMS.ino
@@ -11,20 +11,25 @@
  *****************************************/
 // MD menu items
 static const char SMSMenuItem1[] PROGMEM = "Read Rom";
-static const char SMSMenuItem2[] PROGMEM = "Reset";
-static const char* const menuOptionsSMS[] PROGMEM = {SMSMenuItem1, SMSMenuItem2};
+static const char SMSMenuItem2[] PROGMEM = "Read Rom Retrode";
+static const char SMSMenuItem3[] PROGMEM = "Reset";
+static const char* const menuOptionsSMS[] PROGMEM = {SMSMenuItem1, SMSMenuItem2, SMSMenuItem3};
+
+// Set retrode_mode to true when using a retrode SMS/GG adapter
+static bool retrode_mode = false;
 
 void smsMenu() {
   // create menu with title and 2 options to choose from
   unsigned char mainMenu;
   // Copy menuOptions out of progmem
-  convertPgm(menuOptionsSMS, 2);
-  mainMenu = question_box(F("Sega Master System"), menuOptions, 2, 0);
+  convertPgm(menuOptionsSMS, 3);
+  mainMenu = question_box(F("Sega Master System"), menuOptions, 3, 0);
 
   // wait for user choice to come back from the question box menu
   switch (mainMenu)
   {
     case 0:
+      retrode_mode = false;
       display_Clear();
       mode = mode_SMS;
       setup_SMS();
@@ -34,10 +39,21 @@ void smsMenu() {
       break;
 
     case 1:
+      retrode_mode = true;
+      display_Clear();
+      mode = mode_SMS;
+      setup_SMS();
+      // Change working dir to root
+      sd.chdir("/");
+      readROM_SMS();
+      break;
+
+    case 2:
       // Reset
       resetArduino();
       break;
   }
+  println_Msg(retrode_mode ? F("Retrode Mode On") : F("Retrode Mode Off"));
   println_Msg(F(""));
   println_Msg(F("Press Button..."));
   display_Update();
@@ -56,15 +72,30 @@ void setup_SMS() {
   //A15
   DDRH |= (1 << 3);
 
-  // Set Control Pins to Output RST(PH0) WR(PH5) OE(PH6)
-  DDRH |= (1 << 0) | (1 << 5) | (1 << 6);
-  // CE(PL1)
-  DDRL |= (1 << 1);
+  if (retrode_mode) {
+    // Set Control Pins to Output OE(PH6)
+    DDRH |= (1 << 6);
+    // WR(PL5) and RD(PL6)
+    DDRL |= (1 << 5) | (1 << 6);
 
-  // Setting RST(PH0) WR(PH5) OE(PH6) HIGH
-  PORTH |= (1 << 0) | (1 << 5) | (1 << 6);
-  // CE(PL1)
-  PORTL |= (1 << 1);
+    // Setting OE(PH6) HIGH
+    PORTH |= (1 << 6);
+    //PORTH &= ~(1 << 6); // set OE LOW
+    // Setting WR(PL5) and RD(PL6) HIGH
+    PORTL |= (1 << 5) | (1 << 6);
+    // RD(PL6)
+    //PORTL &= ~(1 << 6); // set RE LOW
+  } else {
+    // Set Control Pins to Output RST(PH0) WR(PH5) OE(PH6)
+    DDRH |= (1 << 0) | (1 << 5) | (1 << 6);
+    // CE(PL1)
+    DDRL |= (1 << 1);
+
+    // Setting RST(PH0) WR(PH5) OE(PH6) HIGH
+    PORTH |= (1 << 0) | (1 << 5) | (1 << 6);
+    // CE(PL1)
+    PORTL |= (1 << 1);
+  }
 
   // ROM has 16KB banks which can be mapped to one of three slots via register writes
   // Register Slot Address space
@@ -88,61 +119,111 @@ void setup_SMS() {
   Low level functions
 *****************************************/
 void writeByte_SMS(word myAddress, byte myData) {
-  // Set Data Pins (D0-D7) to Output
-  DDRC = 0xFF;
+  if (retrode_mode) {
+    // Set Data Pins (D8-D15) to Output
+    DDRA = 0xFF;
+  } else {
+    // Set Data Pins (D0-D7) to Output
+    DDRC = 0xFF;
+  }
 
   // Set address
   PORTF = myAddress & 0xFF;
   PORTK = (myAddress >> 8) & 0xFF;
-  PORTH = (PORTH & 0b11110111) | ((myAddress >> 12) & 0b00001000);
+  if (!retrode_mode) {
+    // CE(PH3) and OE(PH6) are connected
+    PORTH = (PORTH & 0b11110111) | ((myAddress >> 12) & 0b00001000);
+  }
+
   // Output data
-  PORTC = myData;
+  if (retrode_mode) {
+    PORTA = myData;
+  } else {
+    PORTC = myData;
+  }
 
   // Arduino running at 16Mhz -> one nop = 62.5ns
   // Wait till output is stable
   __asm__("nop\n\t""nop\n\t""nop\n\t""nop\n\t");
 
-  // Switch CE(PL1) and WR(PH5) to LOW
-  PORTL &= ~(1 << 1);
-  PORTH &= ~(1 << 5);
+  if (retrode_mode) {
+    // Switch WR(PL5) and OE/CE(PH6) to LOW
+    PORTL &= ~(1 << 5);
+    PORTH &= ~(1 << 6);
+  } else {
+    // Switch CE(PL1) and WR(PH5) to LOW
+    PORTL &= ~(1 << 1);
+    PORTH &= ~(1 << 5);
+  }
 
-  // Leave WE low for at least 60ns
+  // Leave WR low for at least 60ns
   __asm__("nop\n\t""nop\n\t""nop\n\t""nop\n\t");
 
-  // Switch CE(PL1) and WR(PH5) to HIGH
-  PORTH |= (1 << 5);
-  PORTL |= (1 << 1);
+  if (retrode_mode) {
+    // Switch WR(PL5) and OE/CE(PH6) to HIGH
+    PORTH |= (1 << 6);
+    PORTL |= (1 << 5);
+  } else {
+    // Switch CE(PL1) and WR(PH5) to HIGH
+    PORTH |= (1 << 5);
+    PORTL |= (1 << 1);
+  }
 
-  // Leave WE high for at least 50ns
+  // Leave WR high for at least 50ns
   __asm__("nop\n\t""nop\n\t""nop\n\t""nop\n\t");
 
-  // Set Data Pins (D0-D7) to Input
-  DDRC = 0x00;
+  if (retrode_mode) {
+    // Set Data Pins (D8-D15) to Input
+    DDRA = 0x00;
+  } else {
+    // Set Data Pins (D0-D7) to Input
+    DDRC = 0x00;
+  }
 }
 
 byte readByte_SMS(word myAddress) {
-  // Set Data Pins (D0-D7) to Input
-  DDRC = 0x00;
+  if (retrode_mode) {
+    // Set Data Pins (D8-D15) to Input
+    DDRA = 0x00;
+  } else {
+    // Set Data Pins (D0-D7) to Input
+    DDRC = 0x00;
+  }
 
   // Set Address
   PORTF = myAddress & 0xFF;
   PORTK = (myAddress >> 8) & 0xFF;
-  PORTH = (PORTH & 0b11110111) | ((myAddress >> 12) & 0b00001000);
+  if (!retrode_mode) {
+    // CE(PH3) and OE(PH6) are connected
+    PORTH = (PORTH & 0b11110111) | ((myAddress >> 12) & 0b00001000);
+  }
 
   __asm__("nop\n\t""nop\n\t""nop\n\t""nop\n\t");
 
-  // Switch CE(PL1) and OE(PH6) to LOW
-  PORTL &= ~(1 << 1);
-  PORTH &= ~(1 << 6);
+  if (retrode_mode) {
+    // Switch RD(PL6) and OE(PH6) to LOW
+    PORTL &= ~(1 << 6);
+    PORTH &= ~(1 << 6);
+  } else {
+    // Switch CE(PL1) and OE(PH6) to LOW
+    PORTL &= ~(1 << 1);
+    PORTH &= ~(1 << 6);
+  }
 
   __asm__("nop\n\t""nop\n\t""nop\n\t""nop\n\t");
 
   // Read
-  byte tempByte = PINC;
+  byte tempByte = retrode_mode ? PINA : PINC;
 
-  // Switch CE(PL1) and OE(PH6) to HIGH
-  PORTH |= (1 << 6);
-  PORTL |= (1 << 1);
+  if (retrode_mode) {
+    // Switch RD(PL6) and OE(PH6) to HIGH
+    PORTH |= (1 << 6);
+    PORTL |= (1 << 6);
+  } else {
+    // Switch CE(PL1) and OE(PH6) to HIGH
+    PORTH |= (1 << 6);
+    PORTL |= (1 << 1);
+  }
 
   __asm__("nop\n\t""nop\n\t""nop\n\t""nop\n\t");
 
@@ -186,7 +267,11 @@ void getCartInfo_SMS() {
       cartSize =  128 * 1024UL;
       break;
     case 0x0:
-      cartSize =  256 * 1024UL;
+      if (retrode_mode) {
+        cartSize =  512 * 1024UL;
+      } else {
+        cartSize =  256 * 1024UL;
+      }
       break;
     case 0x1:
       cartSize =  512 * 1024UL;