diff --git a/core/cart_hw/sms_cart.c b/core/cart_hw/sms_cart.c
index cee3905..c4aba91 100644
--- a/core/cart_hw/sms_cart.c
+++ b/core/cart_hw/sms_cart.c
@@ -254,6 +254,9 @@ static const rominfo_t game_list[] =
   {0xE42E4998, 0, 0, SYSTEM_SPORTSPAD,   MAPPER_SEGA,   SYSTEM_SMS2,        REGION_USA}, /* Sports Pad Football */
   {0x41C948BF, 0, 0, SYSTEM_SPORTSPAD,   MAPPER_SEGA,   SYSTEM_SMS2,        REGION_USA}, /* Sports Pad Soccer */
 
+  /* games requiring homemade multitap */
+  {0xFAB6F52F, 0, 0, SYSTEM_MS4PLAY,     MAPPER_NONE,   SYSTEM_SMS2,        REGION_USA}, /* BOom */
+
   /* games supporting YM2413 FM */
   {0x1C951F8E, 0, 1, SYSTEM_GAMEPAD,  MAPPER_SEGA,   SYSTEM_SMS2,        REGION_USA}, /* After Burner */
   {0xC13896D5, 0, 1, SYSTEM_GAMEPAD,  MAPPER_SEGA,   SYSTEM_SMS2,        REGION_USA}, /* Alex Kidd: The Lost Stars */
diff --git a/core/input_hw/gamepad.c b/core/input_hw/gamepad.c
index a523b30..7e6ec58 100644
--- a/core/input_hw/gamepad.c
+++ b/core/input_hw/gamepad.c
@@ -1,9 +1,9 @@
 /***************************************************************************************
  *  Genesis Plus
- *  3-Buttons & 6-Buttons pad support
- *  Support for J-CART & 4-Way Play adapters
+ *  2-Buttons, 3-Buttons & 6-Buttons controller support
+ *  Additional support for J-Cart, 4-Way Play & homemade Master System multitap
  *
- *  Copyright (C) 2007-2011  Eke-Eke (Genesis Plus GX)
+ *  Copyright (C) 2007-2014  Eke-Eke (Genesis Plus GX)
  *
  *  Redistribution and use of this code or any derivative works are permitted
  *  provided that the following conditions are met:
@@ -47,7 +47,13 @@ static struct
   uint8 Timeout;
 } gamepad[MAX_DEVICES];
 
-static uint8 pad_index;
+static struct
+{
+  uint8 Latch;
+  uint8 Counter;
+} flipflop[2];
+
+static uint8 latch;
 
 
 void gamepad_reset(int port)
@@ -57,8 +63,12 @@ void gamepad_reset(int port)
   gamepad[port].Counter = 0;
   gamepad[port].Timeout = 0;
 
-  /* reset pad index (4-WayPlay) */
-  pad_index = 0;
+  /* reset 4-WayPlay latch */
+  latch = 0;
+
+  /* reset Master System multitap flip-flop */
+  flipflop[port>>2].Latch = 0;
+  flipflop[port>>2].Counter = 0;
 }
 
 void gamepad_refresh(int port)
@@ -192,13 +202,15 @@ void gamepad_2_write(unsigned char data, unsigned char mask)
 
 unsigned char wayplay_1_read(void)
 {
-  if (pad_index < 4)
+  /* check if TH on port B is HIGH */
+  if (latch & 0x04)
   {
-    return gamepad_read(pad_index);
+    /* 4-WayPlay detection : xxxxx00 */
+    return 0x7c;
   }
 
-  /* multitap detection */
-  return 0x70;
+  /* TR & TL on port B select controller # (0-3) */
+  return gamepad_read(latch);
 }
 
 unsigned char wayplay_2_read(void)
@@ -208,18 +220,14 @@ unsigned char wayplay_2_read(void)
 
 void wayplay_1_write(unsigned char data, unsigned char mask)
 {
-  if (pad_index < 4)
-  {
-    gamepad_write(pad_index, data, mask);
-  }
+  /* TR & TL on port B select controller # (0-3) */
+  gamepad_write(latch & 0x03, data, mask);
 }
 
 void wayplay_2_write(unsigned char data, unsigned char mask)
 {
-  if ((mask & 0x70) == 0x70)
-  {
-    pad_index = (data & 0x70) >> 4;
-  }
+  /* latch TH, TR & TL state on port B */
+  latch = ((data & mask) >> 4) & 0x07;
 }
 
 
@@ -239,3 +247,48 @@ void jcart_write(unsigned int address, unsigned int data)
   gamepad_write(6, (data & 1) << 6, 0x40);
   return;
 }
+
+
+/*--------------------------------------------------------------------------*/
+/*  Master System multitap ports handler (original design by Furrtek)       */
+/*  cf. http://www.smspower.org/uploads/Homebrew/BOoM-SMS-sms4p_2.png       */
+/*--------------------------------------------------------------------------*/
+unsigned char ms4play_1_read(void)
+{
+  return gamepad_read(flipflop[0].Counter);
+}
+
+unsigned char ms4play_2_read(void)
+{
+  return gamepad_read(flipflop[1].Counter + 4);
+}
+
+void ms4play_1_write(unsigned char data, unsigned char mask)
+{
+  /* update bits set as output only */
+  data = (flipflop[0].Latch & ~mask) | (data & mask);
+  
+  /* check TH 1->0 transitions */
+  if ((flipflop[0].Latch & 0x40) && !(data & 0x40))
+  {
+    flipflop[0].Counter = (flipflop[0].Counter + 1) & 0x03;
+  }
+
+  /* update internal state */
+  flipflop[0].Latch = data;
+}
+
+void ms4play_2_write(unsigned char data, unsigned char mask)
+{
+  /* update bits set as output only */
+  data = (flipflop[1].Latch & ~mask) | (data & mask);
+  
+  /* check TH=1 to TH=0 transition */
+  if ((flipflop[1].Latch & 0x40) && !(data & 0x40))
+  {
+    flipflop[1].Counter = (flipflop[1].Counter + 1) & 0x03;
+  }
+
+  /* update internal state */
+  flipflop[1].Latch = data;
+}
diff --git a/core/input_hw/gamepad.h b/core/input_hw/gamepad.h
index 5100e01..9c75bde 100644
--- a/core/input_hw/gamepad.h
+++ b/core/input_hw/gamepad.h
@@ -1,9 +1,9 @@
 /***************************************************************************************
  *  Genesis Plus
- *  3-Buttons & 6-Buttons pad support
- *  Support for J-CART & 4-Way Play adapters
+ *  2-Buttons, 3-Buttons & 6-Buttons controller support
+ *  Additional support for J-Cart, 4-Way Play & homemade Master System multitap
  *
- *  Copyright (C) 2007-2011  Eke-Eke (Genesis Plus GX)
+ *  Copyright (C) 2007-2014  Eke-Eke (Genesis Plus GX)
  *
  *  Redistribution and use of this code or any derivative works are permitted
  *  provided that the following conditions are met:
@@ -53,5 +53,9 @@ extern void wayplay_1_write(unsigned char data, unsigned char mask);
 extern void wayplay_2_write(unsigned char data, unsigned char mask);
 extern unsigned int jcart_read(unsigned int address);
 extern void jcart_write(unsigned int address, unsigned int data);
+extern unsigned char ms4play_1_read(void);
+extern unsigned char ms4play_2_read(void);
+extern void ms4play_1_write(unsigned char data, unsigned char mask);
+extern void ms4play_2_write(unsigned char data, unsigned char mask);
 
 #endif
diff --git a/core/input_hw/input.c b/core/input_hw/input.c
index f318008..3ad7958 100644
--- a/core/input_hw/input.c
+++ b/core/input_hw/input.c
@@ -170,6 +170,19 @@ void input_init(void)
       break;
     }
 
+    case SYSTEM_MS4PLAY:
+    {
+      for (i=0; i<4; i++)
+      {
+        if (player < MAX_INPUTS)
+        {
+          input.dev[i] = DEVICE_PAD2B;
+          player++;
+        }
+      }
+      break;
+    }
+
     case SYSTEM_LIGHTPHASER:
     {
       input.dev[0] = DEVICE_LIGHTGUN;
@@ -276,6 +289,19 @@ void input_init(void)
       break;
     }
 
+    case SYSTEM_MS4PLAY:
+    {
+      for (i=4; i<8; i++)
+      {
+        if (player < MAX_INPUTS)
+        {
+          input.dev[i] = DEVICE_PAD2B;
+          player++;
+        }
+      }
+      break;
+    }
+
     case SYSTEM_LIGHTPHASER:
     {
       input.dev[4] = DEVICE_LIGHTGUN;
diff --git a/core/input_hw/input.h b/core/input_hw/input.h
index 23715e9..f6fdec0 100644
--- a/core/input_hw/input.h
+++ b/core/input_hw/input.h
@@ -51,12 +51,12 @@
 #define SYSTEM_JUSTIFIER    (4) /* Konami Justifiers (port B only) */
 #define SYSTEM_XE_A1P       (5) /* XE-A1P analog controller (port A only) */
 #define SYSTEM_ACTIVATOR    (6) /* Sega Activator */
-#define SYSTEM_MS_GAMEPAD   (7) /* single 2-buttons Control Pad (Master System) */
 #define SYSTEM_LIGHTPHASER  (7) /* Sega Light Phaser (Master System) */
 #define SYSTEM_PADDLE       (8) /* Sega Paddle Control (Master System) */
 #define SYSTEM_SPORTSPAD    (9) /* Sega Sports Pad (Master System) */
-#define SYSTEM_TEAMPLAYER  (10) /* Multi Tap -- Sega TeamPlayer */
-#define SYSTEM_WAYPLAY     (11) /* Multi Tap -- EA 4-Way Play (use both ports) */
+#define SYSTEM_MS4PLAY     (10) /* Multi Tap -- Master System homemade */
+#define SYSTEM_TEAMPLAYER  (11) /* Multi Tap -- Sega TeamPlayer */
+#define SYSTEM_WAYPLAY     (12) /* Multi Tap -- EA 4-Way Play (use both ports) */
 
 /* Device type */
 #define NO_DEVICE         (0xff) /* unconnected device (fixed ID for Team Player) */
diff --git a/core/io_ctrl.c b/core/io_ctrl.c
index 398b8f8..7dfcf3d 100644
--- a/core/io_ctrl.c
+++ b/core/io_ctrl.c
@@ -122,6 +122,13 @@ void io_init(void)
       break;
     }
 
+    case SYSTEM_MS4PLAY:
+    {
+      port[0].data_w = ms4play_1_write;
+      port[0].data_r = ms4play_1_read;
+      break;
+    }
+
     case SYSTEM_LIGHTPHASER:
     {
       port[0].data_w = dummy_write;
@@ -209,6 +216,13 @@ void io_init(void)
       break;
     }
 
+    case SYSTEM_MS4PLAY:
+    {
+      port[1].data_w = ms4play_2_write;
+      port[1].data_r = ms4play_2_read;
+      break;
+    }
+
     case SYSTEM_LIGHTPHASER:
     {
       port[1].data_w = dummy_write;
diff --git a/gx/gui/menu.c b/gx/gui/menu.c
index 2f88420..d170f01 100644
--- a/gx/gui/menu.c
+++ b/gx/gui/menu.c
@@ -108,6 +108,7 @@ extern const u8 Ctrl_paddle_png[];
 extern const u8 Ctrl_sportspad_png[];
 extern const u8 Ctrl_none_png[];
 extern const u8 Ctrl_teamplayer_png[];
+extern const u8 Ctrl_ms4play_png[];
 extern const u8 Ctrl_pad_auto_png[];
 extern const u8 Ctrl_pad2b_png[];
 extern const u8 Ctrl_pad3b_png[];
@@ -2028,7 +2029,7 @@ static void ctrlmenu(void)
   u32 exp, index = 0;
 
   /* System devices */
-  gui_item items_sys[2][12] =
+  gui_item items_sys[2][13] =
   {
     {
       {NULL,Ctrl_none_png       ,"","Select Port 1 device",110,130,48,72},
@@ -2041,6 +2042,7 @@ static void ctrlmenu(void)
       {NULL,Ctrl_lightphaser_png,"","Select Port 1 device", 89,109,88,92},
       {NULL,Ctrl_paddle_png     ,"","Select Port 1 device", 86,117,96,84},
       {NULL,Ctrl_sportspad_png  ,"","Select Port 1 device", 95,117,76,84},
+      {NULL,Ctrl_ms4play_png    ,"","Select Port 1 device", 94,100,80,100},
       {NULL,Ctrl_teamplayer_png ,"","Select Port 1 device", 94,109,80,92},
       {NULL,Ctrl_4wayplay_png   ,"","Select Port 1 device", 98,110,72,92}
     },
@@ -2055,6 +2057,7 @@ static void ctrlmenu(void)
       {NULL,Ctrl_lightphaser_png,"","Select Port 2 device", 89,279,88,92},
       {NULL,Ctrl_paddle_png     ,"","Select Port 2 device", 86,287,96,84},
       {NULL,Ctrl_sportspad_png  ,"","Select Port 2 device", 95,287,76,84},
+      {NULL,Ctrl_ms4play_png    ,"","Select Port 1 device", 94,270,80,100},
       {NULL,Ctrl_teamplayer_png ,"","Select Port 2 device", 94,279,80,92},
       {NULL,Ctrl_4wayplay_png   ,"","Select Port 2 device", 98,280,72,92}
     }
@@ -2121,7 +2124,7 @@ static void ctrlmenu(void)
   button_player_none_data.texture[0] = gxTextureOpenPNG(button_player_none_data.image[0],0);
 
   /* initialize custom images */
-  for (i=0; i<12; i++)
+  for (i=0; i<13; i++)
   {
     items_sys[1][i].texture = items_sys[0][i].texture = gxTextureOpenPNG(items_sys[0][i].data,0);
   }
@@ -2415,8 +2418,17 @@ static void ctrlmenu(void)
             case DEVICE_PAD3B:
             case DEVICE_PAD6B:
             {
-              items = items_special[0];
-              special = &config.input[player].padtype;
+              if (input.system[index/4] == SYSTEM_MS4PLAY)
+              {
+                /* force 2-buttons pad */
+                items = items_special[3];
+                special = NULL;
+              }
+              else
+              {
+                items = items_special[0];
+                special = &config.input[player].padtype;
+              }
               break;
             }
 
diff --git a/gx/images/Ctrl_ms4play.png b/gx/images/Ctrl_ms4play.png
new file mode 100644
index 0000000..3a05924
Binary files /dev/null and b/gx/images/Ctrl_ms4play.png differ