diff --git a/Core/debugger.c b/Core/debugger.c
index 7a7fd87..b560011 100644
--- a/Core/debugger.c
+++ b/Core/debugger.c
@@ -1546,16 +1546,20 @@ static bool mbc(GB_gameboy_t *gb, char *arguments, char *modifiers, const debugg
         }
         else {
             static const char *const mapper_names[] = {
-                [GB_MBC1] = "MBC1",
-                [GB_MBC2] = "MBC2",
-                [GB_MBC3] = "MBC3",
-                [GB_MBC5] = "MBC5",
-                [GB_MBC7] = "MBC7",
-                [GB_HUC1] = "HUC-1",
-                [GB_HUC3] = "HUC-3",
+                [GB_MBC1]  = "MBC1",
+                [GB_MBC2]  = "MBC2",
+                [GB_MBC3]  = "MBC3",
+                [GB_MBC5]  = "MBC5",
+                [GB_MBC7]  = "MBC7",
+                [GB_MMM01] = "MMM01",
+                [GB_HUC1]  = "HUC-1",
+                [GB_HUC3]  = "HUC-3",
             };
             GB_log(gb, "%s\n", mapper_names[cartridge->mbc_type]);
         }
+        if (cartridge->mbc_type == GB_MMM01 || cartridge->mbc_type == GB_MBC1) {
+            GB_log(gb, "Current mapped ROM0 bank: %x\n", gb->mbc_rom0_bank);
+        }
         GB_log(gb, "Current mapped ROM bank: %x\n", gb->mbc_rom_bank);
         if (cartridge->has_ram) {
             GB_log(gb, "Current mapped RAM bank: %x\n", gb->mbc_ram_bank);
diff --git a/Core/gb.c b/Core/gb.c
index 0b5081a..3c230bd 100644
--- a/Core/gb.c
+++ b/Core/gb.c
@@ -1609,7 +1609,8 @@ void GB_reset(GB_gameboy_t *gb)
     gb->model = model;
     gb->version = GB_STRUCT_VERSION;
     
-    gb->mbc_rom_bank = 1;
+    GB_reset_mbc(gb);
+    
     gb->last_rtc_second = time(NULL);
     gb->cgb_ram_bank = 1;
     gb->io_registers[GB_IO_JOYP] = 0xCF;
diff --git a/Core/gb.h b/Core/gb.h
index 0405c4a..2937032 100644
--- a/Core/gb.h
+++ b/Core/gb.h
@@ -440,6 +440,7 @@ struct GB_gameboy_internal_s {
     /* MBC */
     GB_SECTION(mbc,
         uint16_t mbc_rom_bank;
+        uint16_t mbc_rom0_bank; /* For multicart mappings . */
         uint8_t mbc_ram_bank;
         uint32_t mbc_ram_size;
         bool mbc_ram_enable;
@@ -466,21 +467,38 @@ struct GB_gameboy_internal_s {
                 uint8_t ram_bank:4;
             } mbc5;
                
-           struct {
-               uint8_t rom_bank;
-               uint16_t x_latch;
-               uint16_t y_latch;
-               bool latch_ready:1;
-               bool eeprom_do:1;
-               bool eeprom_di:1;
-               bool eeprom_clk:1;
-               bool eeprom_cs:1;
-               uint16_t eeprom_command:11;
-               uint16_t read_bits;
-               uint8_t bits_countdown:5;
-               bool secondary_ram_enable:1;
-               bool eeprom_write_enabled:1;
-           } mbc7;
+            struct {
+                uint8_t rom_bank;
+                uint16_t x_latch;
+                uint16_t y_latch;
+                bool latch_ready:1;
+                bool eeprom_do:1;
+                bool eeprom_di:1;
+                bool eeprom_clk:1;
+                bool eeprom_cs:1;
+                uint16_t eeprom_command:11;
+                uint16_t read_bits;
+                uint8_t bits_countdown:5;
+                bool secondary_ram_enable:1;
+                bool eeprom_write_enabled:1;
+            } mbc7;
+               
+            struct {
+                uint8_t rom_bank_low:5;
+                uint8_t rom_bank_mid:2;
+                bool mbc1_mode:1;
+               
+                uint8_t rom_bank_mask:4;
+                uint8_t rom_bank_high:2;
+                uint8_t ram_bank_low:2;
+               
+                uint8_t ram_bank_high:2;
+                uint8_t ram_bank_mask:2;
+
+                bool locked:1;
+                bool mbc1_mode_disable:1;
+                bool multiplex_mode:1;
+            } mmm01;
             
             struct {
                 uint8_t bank_low:6;
@@ -508,7 +526,6 @@ struct GB_gameboy_internal_s {
                uint8_t mode;
            } tpp1;
         };
-        uint16_t mbc_rom0_bank; /* For some MBC1 wirings. */
         bool camera_registers_mapped;
         uint8_t camera_registers[0x36];
         uint8_t rumble_strength;
diff --git a/Core/mbc.c b/Core/mbc.c
index d330d8e..da798b1 100644
--- a/Core/mbc.c
+++ b/Core/mbc.c
@@ -18,9 +18,9 @@ const GB_cartridge_t GB_cart_defs[256] = {
     {  GB_NO_MBC, GB_STANDARD_MBC, true , true , false, false}, // 09h  ROM+RAM+BATTERY
     [0xB] =
     /* Todo: Not supported yet */
-    {  GB_NO_MBC, GB_STANDARD_MBC, false, false, false, false}, // 0Bh  MMM01
-    {  GB_NO_MBC, GB_STANDARD_MBC, false, false, false, false}, // 0Ch  MMM01+RAM
-    {  GB_NO_MBC, GB_STANDARD_MBC, false, false, false, false}, // 0Dh  MMM01+RAM+BATTERY
+    {  GB_MMM01 , GB_STANDARD_MBC, false, false, false, false}, // 0Bh  MMM01
+    {  GB_MMM01 , GB_STANDARD_MBC, true , false, false, false}, // 0Ch  MMM01+RAM
+    {  GB_MMM01 , GB_STANDARD_MBC, true , true , false, false}, // 0Dh  MMM01+RAM+BATTERY
     [0xF] =
     {  GB_MBC3  , GB_STANDARD_MBC, false, true,  true , false}, // 0Fh  MBC3+TIMER+BATTERY
     {  GB_MBC3  , GB_STANDARD_MBC, true , true,  true , false}, // 10h  MBC3+TIMER+RAM+BATTERY
@@ -103,6 +103,40 @@ void GB_update_mbc_mappings(GB_gameboy_t *gb)
         case GB_MBC7:
             gb->mbc_rom_bank = gb->mbc7.rom_bank;
             break;
+        case GB_MMM01:
+            if (gb->mmm01.locked) {
+                if (gb->mmm01.multiplex_mode) {
+                    gb->mbc_rom0_bank = (gb->mmm01.rom_bank_low & (gb->mmm01.rom_bank_mask << 1)) |
+                        ((gb->mmm01.rom_bank_low & (gb->mmm01.mbc1_mode? -1 : gb->mmm01.ram_bank_mask)) << 5) |
+                        (gb->mmm01.rom_bank_high << 7);
+                    gb->mbc_rom_bank = gb->mmm01.rom_bank_low |
+                        (gb->mmm01.rom_bank_low << 5) |
+                        (gb->mmm01.rom_bank_high << 7);
+                    gb->mbc_ram_bank = gb->mmm01.rom_bank_mid | (gb->mmm01.ram_bank_high << 2);
+                }
+                else {
+                    gb->mbc_rom0_bank = (gb->mmm01.rom_bank_low & (gb->mmm01.rom_bank_mask << 1)) |
+                        (gb->mmm01.rom_bank_mid << 5) |
+                        (gb->mmm01.rom_bank_high << 7);
+                    gb->mbc_rom_bank = gb->mmm01.rom_bank_low |
+                        (gb->mmm01.rom_bank_mid << 5) |
+                        (gb->mmm01.rom_bank_high << 7);
+                    if (gb->mmm01.mbc1_mode) {
+                        gb->mbc_ram_bank = gb->mmm01.ram_bank_low | (gb->mmm01.ram_bank_high << 2);
+                    }
+                    else {
+                        gb->mbc_ram_bank = (gb->mmm01.ram_bank_low & gb->mmm01.ram_bank_mask) | (gb->mmm01.ram_bank_high << 2);
+                    }
+                }
+                if (gb->mbc_rom_bank == gb->mbc_rom0_bank) {
+                    gb->mbc_rom_bank++;
+                }
+            }
+            else {
+                gb->mbc_rom_bank = -1;
+                gb->mbc_rom0_bank = -2;
+            }
+            break;
         case GB_HUC1:
             if (gb->huc1.mode == 0) {
                 gb->mbc_rom_bank = gb->huc1.bank_low | (gb->mbc1.bank_high << 6);
@@ -129,6 +163,20 @@ void GB_update_mbc_mappings(GB_gameboy_t *gb)
 void GB_configure_cart(GB_gameboy_t *gb)
 {
     gb->cartridge_type = &GB_cart_defs[gb->rom[0x147]];
+    if (gb->cartridge_type->mbc_type == GB_MMM01) {
+        uint8_t *temp = malloc(0x8000);
+        memcpy(temp, gb->rom, 0x8000);
+        memmove(gb->rom, gb->rom + 0x8000, gb->rom_size - 0x8000);
+        memcpy(gb->rom + gb->rom_size - 0x8000, temp, 0x8000);
+        free(temp);
+    }
+    else {
+        const GB_cartridge_t *maybe_mmm01_type = &GB_cart_defs[gb->rom[gb->rom_size - 0x8000 + 0x147]];
+        if (maybe_mmm01_type->mbc_type == GB_MMM01 && memcmp(gb->rom + 0x104, gb->rom + gb->rom_size - 0x8000 + 0x104, 0x30) == 0) {
+            gb->cartridge_type = maybe_mmm01_type;
+        }
+    }
+
     if (gb->rom[0x147] == 0xBC &&
         gb->rom[0x149] == 0xC1 &&
         gb->rom[0x14A] == 0x65) {
@@ -193,16 +241,25 @@ void GB_configure_cart(GB_gameboy_t *gb)
         }
     }
     
-    /* Set MBC5's bank to 1 correctly */
-    if (gb->cartridge_type->mbc_type == GB_MBC5) {
+    GB_reset_mbc(gb);
+}
+
+void GB_reset_mbc(GB_gameboy_t *gb)
+{
+    if (gb->cartridge_type->mbc_type == GB_MMM01) {
+        gb->mbc_rom_bank = -1;
+        gb->mbc_rom0_bank = -2;
+    }
+    else if (gb->cartridge_type->mbc_type == GB_MBC5) {
         gb->mbc5.rom_bank_low = 1;
     }
-    
-    /* Initial MBC7 state */
-    if (gb->cartridge_type->mbc_type == GB_MBC7) {
+    else if (gb->cartridge_type->mbc_type == GB_MBC7) {
         gb->mbc7.x_latch = gb->mbc7.y_latch = 0x8000;
         gb->mbc7.latch_ready = true;
         gb->mbc7.read_bits = -1;
         gb->mbc7.eeprom_do = true;
     }
+    else {
+        gb->mbc_rom_bank = 1;
+    }
 }
diff --git a/Core/mbc.h b/Core/mbc.h
index 7e6cc82..c3f6190 100644
--- a/Core/mbc.h
+++ b/Core/mbc.h
@@ -11,6 +11,7 @@ typedef struct {
         GB_MBC3,
         GB_MBC5,
         GB_MBC7,
+        GB_MMM01,
         GB_HUC1,
         GB_HUC3,
         GB_TPP1,
@@ -26,9 +27,10 @@ typedef struct {
 } GB_cartridge_t;
 
 #ifdef GB_INTERNAL
-extern const GB_cartridge_t GB_cart_defs[256];
+internal extern const GB_cartridge_t GB_cart_defs[256];
 internal void GB_update_mbc_mappings(GB_gameboy_t *gb);
 internal void GB_configure_cart(GB_gameboy_t *gb);
+internal void GB_reset_mbc(GB_gameboy_t *gb);
 #endif
 
 #endif /* MBC_h */
diff --git a/Core/memory.c b/Core/memory.c
index b6a1857..2644f12 100644
--- a/Core/memory.c
+++ b/Core/memory.c
@@ -838,6 +838,42 @@ static void write_mbc(GB_gameboy_t *gb, uint16_t addr, uint8_t value)
                 case 0x4000: case 0x5000: gb->mbc7.secondary_ram_enable  = value == 0x40; break;
             }
             break;
+        case GB_MMM01:
+            switch (addr & 0xF000) {
+                case 0x0000: case 0x1000:
+                    gb->mbc_ram_enable = (value & 0xF) == 0xA;
+                    if (!gb->mmm01.locked) {
+                        gb->mmm01.ram_bank_mask = value >> 4;
+                        gb->mmm01.locked = value & 0x40;
+                    }
+                    break;
+                case 0x2000: case 0x3000:
+                    if (!gb->mmm01.locked) {
+                        gb->mmm01.rom_bank_mid = value >> 5;
+                        gb->mmm01.rom_bank_low = value;
+                    }
+                    else {
+                        gb->mmm01.rom_bank_low &= (gb->mmm01.rom_bank_mask << 1);
+                        gb->mmm01.rom_bank_low |= ~(gb->mmm01.rom_bank_mask << 1) & value;
+                    }
+                    break;
+                case 0x4000: case 0x5000:
+                    gb->mmm01.ram_bank_low = value;
+                    if (!gb->mmm01.locked) {
+                        gb->mmm01.ram_bank_high = value >> 2;
+                        gb->mmm01.rom_bank_high = value >> 4;
+                        gb->mmm01.mbc1_mode_disable = value & 0x40;
+                    }
+                    break;
+                case 0x6000: case 0x7000:
+                    gb->mmm01.mbc1_mode = (value & 1) && !gb->mmm01.mbc1_mode_disable;
+                    if (!gb->mmm01.locked) {
+                        gb->mmm01.rom_bank_mask = value >> 2;
+                        gb->mmm01.multiplex_mode = value & 0x40;
+                    }
+                    break;
+            }
+            break;
         case GB_HUC1:
             switch (addr & 0xF000) {
                 case 0x0000: case 0x1000: gb->huc1.ir_mode = (value & 0xF) == 0xE; break;
diff --git a/Core/save_state.c b/Core/save_state.c
index 3b8dad5..f22df13 100644
--- a/Core/save_state.c
+++ b/Core/save_state.c
@@ -232,6 +232,8 @@ static size_t bess_size_for_cartridge(const GB_cartridge_t *cart)
             return sizeof(BESS_block_t) + 3 * sizeof(BESS_MBC_pair_t) + (cart->has_rtc? sizeof(BESS_RTC_t) : 0);
         case GB_MBC5:
             return sizeof(BESS_block_t) + 4 * sizeof(BESS_MBC_pair_t);
+        case GB_MMM01:
+            return sizeof(BESS_block_t) + 4 * sizeof(BESS_MBC_pair_t);
         case GB_HUC1:
             return sizeof(BESS_block_t) + 4 * sizeof(BESS_MBC_pair_t);
         case GB_HUC3:
@@ -435,20 +437,25 @@ static int save_bess_mbc_block(GB_gameboy_t *gb, virtual_file_t *file)
             pairs[3] = (BESS_MBC_pair_t){LE16(0x4000), gb->mbc5.ram_bank};
             mbc_block.size = 4 * sizeof(pairs[0]);
             break;
+        case GB_MMM01:
+            pairs[0] = (BESS_MBC_pair_t){LE16(0x2000), gb->mmm01.rom_bank_low | (gb->mmm01.rom_bank_mid << 5)};
+            pairs[1] = (BESS_MBC_pair_t){LE16(0x6000), gb->mmm01.mbc1_mode | (gb->mmm01.rom_bank_mask << 2) | (gb->mmm01.multiplex_mode << 6)};
+            pairs[2] = (BESS_MBC_pair_t){LE16(0x4000), gb->mmm01.ram_bank_low | (gb->mmm01.ram_bank_high << 2) | (gb->mmm01.rom_bank_high << 4) | (gb->mmm01.mbc1_mode_disable << 6)};
+            pairs[3] = (BESS_MBC_pair_t){LE16(0x0000), (gb->mbc_ram_enable? 0xA : 0x0) | (gb->mmm01.ram_bank_mask << 4) | (gb->mmm01.locked << 6)};
+            mbc_block.size = 4 * sizeof(pairs[0]);
+            break;
         case GB_HUC1:
             pairs[0] = (BESS_MBC_pair_t){LE16(0x0000), gb->huc1.ir_mode? 0xE : 0x0};
             pairs[1] = (BESS_MBC_pair_t){LE16(0x2000), gb->huc1.bank_low};
             pairs[2] = (BESS_MBC_pair_t){LE16(0x4000), gb->huc1.bank_high};
             pairs[3] = (BESS_MBC_pair_t){LE16(0x6000), gb->huc1.mode};
             mbc_block.size = 4 * sizeof(pairs[0]);
-            
         case GB_HUC3:
             pairs[0] = (BESS_MBC_pair_t){LE16(0x0000), gb->huc3.mode};
             pairs[1] = (BESS_MBC_pair_t){LE16(0x2000), gb->huc3.rom_bank};
             pairs[2] = (BESS_MBC_pair_t){LE16(0x4000), gb->huc3.ram_bank};
             mbc_block.size = 3 * sizeof(pairs[0]);
             break;
-        
         case GB_TPP1:
             pairs[0] = (BESS_MBC_pair_t){LE16(0x0000), gb->tpp1.rom_bank};
             pairs[1] = (BESS_MBC_pair_t){LE16(0x0001), gb->tpp1.rom_bank >> 8};