diff --git a/input.c b/input.c
index 44455d2..9aef248 100644
--- a/input.c
+++ b/input.c
@@ -24,6 +24,11 @@ bool libretro_supports_ff_override = false;
 bool libretro_ff_enabled           = false;
 bool libretro_ff_enabled_prev      = false;
 
+unsigned turbo_period      = TURBO_PERIOD_MIN;
+unsigned turbo_pulse_width = TURBO_PULSE_WIDTH_MIN;
+unsigned turbo_a_counter   = 0;
+unsigned turbo_b_counter   = 0;
+
 static u32 old_key = 0;
 static retro_input_state_t input_state_cb;
 
@@ -56,6 +61,8 @@ u32 update_input(void)
 {
    unsigned i;
    uint32_t new_key = 0;
+   bool turbo_a     = false;
+   bool turbo_b     = false;
 
    if (!input_state_cb)
       return 0;
@@ -69,6 +76,9 @@ u32 update_input(void)
 
       libretro_ff_enabled = libretro_supports_ff_override &&
             (ret & (1 << RETRO_DEVICE_ID_JOYPAD_R2));
+
+      turbo_a = (ret & (1 << RETRO_DEVICE_ID_JOYPAD_X));
+      turbo_b = (ret & (1 << RETRO_DEVICE_ID_JOYPAD_Y));
    }
    else
    {
@@ -77,8 +87,36 @@ u32 update_input(void)
 
        libretro_ff_enabled = libretro_supports_ff_override &&
             input_state_cb(0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_R2);
+
+      turbo_a = input_state_cb(0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_X);
+      turbo_b = input_state_cb(0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_Y);
    }
 
+   /* Handle turbo buttons */
+   if (turbo_a)
+   {
+      new_key |= (turbo_a_counter < turbo_pulse_width) ?
+            BUTTON_A : 0;
+
+      turbo_a_counter++;
+      if (turbo_a_counter >= turbo_period)
+         turbo_a_counter = 0;
+   }
+   else
+      turbo_a_counter = 0;
+
+   if (turbo_b)
+   {
+      new_key |= (turbo_b_counter < turbo_pulse_width) ?
+            BUTTON_B : 0;
+
+      turbo_b_counter++;
+      if (turbo_b_counter >= turbo_period)
+         turbo_b_counter = 0;
+   }
+   else
+      turbo_b_counter = 0;
+
    if ((new_key | old_key) != old_key)
       trigger_key(new_key);
 
diff --git a/input.h b/input.h
index 90fc930..72c7e1e 100644
--- a/input.h
+++ b/input.h
@@ -61,6 +61,18 @@ extern bool libretro_supports_ff_override;
 extern bool libretro_ff_enabled;
 extern bool libretro_ff_enabled_prev;
 
+/* Minimum (and default) turbo pulse train
+ * is 2 frames ON, 2 frames OFF */
+#define TURBO_PERIOD_MIN      4
+#define TURBO_PERIOD_MAX      120
+#define TURBO_PULSE_WIDTH_MIN 2
+#define TURBO_PULSE_WIDTH_MAX 15
+
+extern unsigned turbo_period;
+extern unsigned turbo_pulse_width;
+extern unsigned turbo_a_counter;
+extern unsigned turbo_b_counter;
+
 void init_input(void);
 u32 update_input(void);
 void input_write_savestate(void);
diff --git a/libretro.c b/libretro.c
index 28db9dd..5dfe0df 100644
--- a/libretro.c
+++ b/libretro.c
@@ -841,6 +841,28 @@ static void check_variables(int started_from_load)
             use_libretro_save_method = 0;
       }
    }
+
+   var.key           = "gpsp_turbo_period";
+   var.value         = NULL;
+   turbo_period      = TURBO_PERIOD_MIN;
+   turbo_pulse_width = TURBO_PULSE_WIDTH_MIN;
+   if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
+   {
+      turbo_period = atoi(var.value);
+      turbo_period = (turbo_period < TURBO_PERIOD_MIN) ?
+            TURBO_PERIOD_MIN : turbo_period;
+      turbo_period = (turbo_period > TURBO_PERIOD_MAX) ?
+            TURBO_PERIOD_MAX : turbo_period;
+
+      turbo_pulse_width = turbo_period >> 1;
+      turbo_pulse_width = (turbo_pulse_width < TURBO_PULSE_WIDTH_MIN) ?
+            TURBO_PULSE_WIDTH_MIN : turbo_pulse_width;
+      turbo_pulse_width = (turbo_pulse_width > TURBO_PULSE_WIDTH_MAX) ?
+            TURBO_PULSE_WIDTH_MAX : turbo_pulse_width;
+
+      turbo_a_counter = 0;
+      turbo_b_counter = 0;
+   }
 }
 
 static void set_input_descriptors()
@@ -852,6 +874,8 @@ static void set_input_descriptors()
       { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_RIGHT,  "D-Pad Right" },
       { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_B,      "B" },
       { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_A,      "A" },
+      { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_Y,      "Turbo B" },
+      { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_X,      "Turbo A" },
       { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_SELECT, "Select" },
       { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_START,  "Start" },
       { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_L,      "L" },
@@ -866,6 +890,8 @@ static void set_input_descriptors()
       { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_RIGHT,  "D-Pad Right" },
       { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_B,      "B" },
       { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_A,      "A" },
+      { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_Y,      "Turbo B" },
+      { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_X,      "Turbo A" },
       { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_SELECT, "Select" },
       { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_START,  "Start" },
       { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_L,      "L" },
@@ -980,6 +1006,11 @@ void retro_unload_game(void)
    libretro_supports_ff_override = false;
    libretro_ff_enabled           = false;
    libretro_ff_enabled_prev      = false;
+
+   turbo_period      = TURBO_PERIOD_MIN;
+   turbo_pulse_width = TURBO_PULSE_WIDTH_MIN;
+   turbo_a_counter   = 0;
+   turbo_b_counter   = 0;
 }
 
 unsigned retro_get_region(void)
@@ -1052,9 +1083,8 @@ void retro_run(void)
 {
    bool updated = false;
 
-   update_input();
-
    input_poll_cb();
+   update_input();
 
    /* Check whether current frame should
     * be skipped */
diff --git a/libretro_core_options.h b/libretro_core_options.h
index d2b95fa..c23a2c3 100644
--- a/libretro_core_options.h
+++ b/libretro_core_options.h
@@ -180,6 +180,132 @@ struct retro_core_option_definition option_defs_us[] = {
       "enabled"
    },
 #endif
+   {
+      "gpsp_turbo_period",
+      "Turbo Button Period",
+      "Specify the repeat interval (in frames) when holding down the Turbo A/B buttons.",
+      {
+         { "4",   NULL },
+         { "5",   NULL },
+         { "6",   NULL },
+         { "7",   NULL },
+         { "8",   NULL },
+         { "9",   NULL },
+         { "10",  NULL },
+         { "11",  NULL },
+         { "12",  NULL },
+         { "13",  NULL },
+         { "14",  NULL },
+         { "15",  NULL },
+         { "16",  NULL },
+         { "17",  NULL },
+         { "18",  NULL },
+         { "19",  NULL },
+         { "20",  NULL },
+         { "21",  NULL },
+         { "22",  NULL },
+         { "23",  NULL },
+         { "24",  NULL },
+         { "25",  NULL },
+         { "26",  NULL },
+         { "27",  NULL },
+         { "28",  NULL },
+         { "29",  NULL },
+         { "30",  NULL },
+         { "31",  NULL },
+         { "32",  NULL },
+         { "33",  NULL },
+         { "34",  NULL },
+         { "35",  NULL },
+         { "36",  NULL },
+         { "37",  NULL },
+         { "38",  NULL },
+         { "39",  NULL },
+         { "40",  NULL },
+         { "41",  NULL },
+         { "42",  NULL },
+         { "43",  NULL },
+         { "44",  NULL },
+         { "45",  NULL },
+         { "46",  NULL },
+         { "47",  NULL },
+         { "48",  NULL },
+         { "49",  NULL },
+         { "50",  NULL },
+         { "51",  NULL },
+         { "52",  NULL },
+         { "53",  NULL },
+         { "54",  NULL },
+         { "55",  NULL },
+         { "56",  NULL },
+         { "57",  NULL },
+         { "58",  NULL },
+         { "59",  NULL },
+         { "60",  NULL },
+         { "61",  NULL },
+         { "62",  NULL },
+         { "63",  NULL },
+         { "64",  NULL },
+         { "65",  NULL },
+         { "66",  NULL },
+         { "67",  NULL },
+         { "68",  NULL },
+         { "69",  NULL },
+         { "70",  NULL },
+         { "71",  NULL },
+         { "72",  NULL },
+         { "73",  NULL },
+         { "74",  NULL },
+         { "75",  NULL },
+         { "76",  NULL },
+         { "77",  NULL },
+         { "78",  NULL },
+         { "79",  NULL },
+         { "80",  NULL },
+         { "81",  NULL },
+         { "82",  NULL },
+         { "83",  NULL },
+         { "84",  NULL },
+         { "85",  NULL },
+         { "86",  NULL },
+         { "87",  NULL },
+         { "88",  NULL },
+         { "89",  NULL },
+         { "90",  NULL },
+         { "91",  NULL },
+         { "92",  NULL },
+         { "93",  NULL },
+         { "94",  NULL },
+         { "95",  NULL },
+         { "96",  NULL },
+         { "97",  NULL },
+         { "98",  NULL },
+         { "99",  NULL },
+         { "100", NULL },
+         { "101", NULL },
+         { "102", NULL },
+         { "103", NULL },
+         { "104", NULL },
+         { "105", NULL },
+         { "106", NULL },
+         { "107", NULL },
+         { "108", NULL },
+         { "109", NULL },
+         { "110", NULL },
+         { "111", NULL },
+         { "112", NULL },
+         { "113", NULL },
+         { "114", NULL },
+         { "115", NULL },
+         { "116", NULL },
+         { "117", NULL },
+         { "118", NULL },
+         { "119", NULL },
+         { "120", NULL },
+         { NULL, NULL },
+      },
+      "4"
+   },
    { NULL, NULL, NULL, {{0}}, NULL },
 };