diff --git a/HISTORY.txt b/HISTORY.txt
index d6392f0..d688c9a 100644
--- a/HISTORY.txt
+++ b/HISTORY.txt
@@ -96,6 +96,7 @@ Genesis Plus GX 1.7.5 (xx/xx/xxxx) (Eke-Eke)
 ---------------
 * added support for new SMS Power Korean dumps (Star Soldier & Pippols)
 * added support for SG-1000 II clone hardware (2KB RAM + integrated VDP/PSG chip 315-5066)
+* added support for SG-1000 II hardware with 8KB RAM extension adapter
 * fixed SG-1000 internal RAM size (1KB instead of 2KB)
 * fixed savestates for games using external RAM
 * restored SG-1000 Pause button support
diff --git a/builds/genesis_plus_gx_libretro.dll b/builds/genesis_plus_gx_libretro.dll
index 5a2ee12..7b36337 100644
Binary files a/builds/genesis_plus_gx_libretro.dll and b/builds/genesis_plus_gx_libretro.dll differ
diff --git a/builds/genplus_cube.dol b/builds/genplus_cube.dol
index 2841d34..464fe29 100644
Binary files a/builds/genplus_cube.dol and b/builds/genplus_cube.dol differ
diff --git a/builds/genplus_wii.dol b/builds/genplus_wii.dol
index 49f5d06..c680350 100644
Binary files a/builds/genplus_wii.dol and b/builds/genplus_wii.dol differ
diff --git a/core/cart_hw/sms_cart.c b/core/cart_hw/sms_cart.c
index 3d4f932..6b3dd43 100644
--- a/core/cart_hw/sms_cart.c
+++ b/core/cart_hw/sms_cart.c
@@ -45,7 +45,6 @@
 #define MAPPER_RAM_2K      (0x02)
 #define MAPPER_RAM_8K      (0x03)
 #define MAPPER_RAM_8K_EXT1 (0x04)
-#define MAPPER_RAM_8K_EXT2 (0x05)
 #define MAPPER_SEGA        (0x10)
 #define MAPPER_SEGA_X      (0x11)
 #define MAPPER_93C46       (0x12)
@@ -160,7 +159,7 @@ static const rominfo_t game_list[] =
   /* games using 8KB external RAM (volatile) */
   {0x092F29D6, 0, 0, 0,  MAPPER_RAM_8K, SYSTEM_SG,   REGION_JAPAN_NTSC}, /* The Castle (J) */
 
-  /* games requiring SG-1000 II 8K RAM extension adapters */
+  /* games requiring SG-1000 II 8K RAM extension adapter (type A) */
   {0xCE5648C3, 0, 0, 0,  MAPPER_RAM_8K_EXT1, SYSTEM_SGII, REGION_JAPAN_NTSC}, /* Bomberman Special [DahJee] (TW) */
   {0x223397A1, 0, 0, 0,  MAPPER_RAM_8K_EXT1, SYSTEM_SGII, REGION_JAPAN_NTSC}, /* King's Valley (TW) */
   {0x281D2888, 0, 0, 0,  MAPPER_RAM_8K_EXT1, SYSTEM_SGII, REGION_JAPAN_NTSC}, /* Knightmare (TW) */
@@ -172,11 +171,13 @@ static const rominfo_t game_list[] =
   {0xFC87463C, 0, 0, 0,  MAPPER_RAM_8K_EXT1, SYSTEM_SGII, REGION_JAPAN_NTSC}, /* Yie Ar Kung-Fu II (TW) */
   {0xDF7CBFA5, 0, 0, 0,  MAPPER_RAM_8K_EXT1, SYSTEM_SGII, REGION_JAPAN_NTSC}, /* Pippols (TW) */
   {0xE0816BB7, 0, 0, 0,  MAPPER_RAM_8K_EXT1, SYSTEM_SGII, REGION_JAPAN_NTSC}, /* Star Soldier (TW) */
-  {0x69FC1494, 0, 0, 0,  MAPPER_RAM_8K_EXT2, SYSTEM_SGII, REGION_JAPAN_NTSC}, /* Bomberman Special (TW) */
-  {0xFFC4EE3F, 0, 0, 0,  MAPPER_RAM_8K_EXT2, SYSTEM_SGII, REGION_JAPAN_NTSC}, /* Magical Kid Wiz (TW) */
-  {0x2E366CCF, 0, 0, 0,  MAPPER_RAM_8K_EXT2, SYSTEM_SGII, REGION_JAPAN_NTSC}, /* The Castle (TW) */
-  {0xAAAC12CF, 0, 0, 0,  MAPPER_RAM_8K_EXT2, SYSTEM_SGII, REGION_JAPAN_NTSC}, /* Rally-X (TW) */
-  {0xD2EDD329, 0, 0, 0,  MAPPER_RAM_8K_EXT2, SYSTEM_SGII, REGION_JAPAN_NTSC}, /* Road Fighter (TW) */
+
+  /* games requiring SG-1000 II 8K RAM extension adapter (type B) */
+  {0x69FC1494, 0, 0, 0,  MAPPER_NONE, SYSTEM_SGII_RAM_EXT, REGION_JAPAN_NTSC}, /* Bomberman Special (TW) */
+  {0xFFC4EE3F, 0, 0, 0,  MAPPER_NONE, SYSTEM_SGII_RAM_EXT, REGION_JAPAN_NTSC}, /* Magical Kid Wiz (TW) */
+  {0x2E366CCF, 0, 0, 0,  MAPPER_NONE, SYSTEM_SGII_RAM_EXT, REGION_JAPAN_NTSC}, /* The Castle (TW) */
+  {0xAAAC12CF, 0, 0, 0,  MAPPER_NONE, SYSTEM_SGII_RAM_EXT, REGION_JAPAN_NTSC}, /* Rally-X (TW) */
+  {0xD2EDD329, 0, 0, 0,  MAPPER_NONE, SYSTEM_SGII_RAM_EXT, REGION_JAPAN_NTSC}, /* Road Fighter (TW) */
 
   /* games requiring 2KB internal RAM (SG-1000 II clone hardware) */
   {0x7F7F009D, 0, 0, 0,  MAPPER_NONE, SYSTEM_SGII, REGION_JAPAN_NTSC}, /* Circus Charlie (KR) */
@@ -883,13 +884,13 @@ static void mapper_reset(void)
   int i;
 
   /* reset $C000-$FFFF mapping */
-  if (cart_rom.mapper == MAPPER_RAM_8K_EXT2)
+  if (system_hw == SYSTEM_SG)
   {
-    /* 8KB RAM extension adapter (type B) */
+    /* original SG-1000 hardware has only 1KB internal RAM */
     for (i = 0x30; i < 0x40; i++)
     {
-      /* $C000-$FFFF mapped to 8KB external RAM (mirrored) */
-      z80_readmap[i] = z80_writemap[i] = &work_ram[(i & 0x07) << 10];
+      /* $C000-$FFFF mapped to 1KB internal RAM (mirrored) */
+      z80_readmap[i] = z80_writemap[i] = &work_ram[0];
     }
   }
   else if (system_hw == SYSTEM_SGII)
@@ -901,18 +902,9 @@ static void mapper_reset(void)
       z80_readmap[i] = z80_writemap[i] = &work_ram[(i & 0x01) << 10];
     }
   }
-  else if (system_hw == SYSTEM_SG)
-  {
-    /* default SG-1000 hardware has only 1KB internal RAM */
-    for (i = 0x30; i < 0x40; i++)
-    {
-      /* $C000-$FFFF mapped to 1KB internal RAM (mirrored) */
-      z80_readmap[i] = z80_writemap[i] = &work_ram[0];
-    }
-  }
   else
   {
-    /* Mark III / Master System / Game Gear hardware */
+    /* Mark III / Master System / Game Gear hardware or SG-1000 II hardware with 8KB RAM extension adapter (type B) */
     for (i = 0x30; i < 0x40; i++)
     {
       /* $C000-$FFFF mapped to 8KB internal RAM (mirrored) */
diff --git a/core/genesis.c b/core/genesis.c
index 11a06d4..a76881f 100644
--- a/core/genesis.c
+++ b/core/genesis.c
@@ -5,7 +5,7 @@
  *  Support for SG-1000, Mark-III, Master System, Game Gear, Mega Drive & Mega CD hardware
  *
  *  Copyright (C) 1998-2003  Charles Mac Donald (original code)
- *  Copyright (C) 2007-2021  Eke-Eke (Genesis Plus GX)
+ *  Copyright (C) 2007-2022  Eke-Eke (Genesis Plus GX)
  *
  *  Redistribution and use of this code or any derivative works are permitted
  *  provided that the following conditions are met:
@@ -221,6 +221,7 @@ void gen_init(void)
       /* SG-1000 hardware */
       case SYSTEM_SG:
       case SYSTEM_SGII:
+      case SYSTEM_SGII_RAM_EXT:
       {
         z80_writeport = z80_sg_port_w;
         z80_readport  = z80_sg_port_r;
diff --git a/core/genesis.h b/core/genesis.h
index 7e1162a..04e0052 100644
--- a/core/genesis.h
+++ b/core/genesis.h
@@ -5,7 +5,7 @@
  *  Support for SG-1000, Mark-III, Master System, Game Gear, Mega Drive & Mega CD hardware
  *
  *  Copyright (C) 1998-2003  Charles Mac Donald (original code)
- *  Copyright (C) 2007-2021  Eke-Eke (Genesis Plus GX)
+ *  Copyright (C) 2007-2022  Eke-Eke (Genesis Plus GX)
  *
  *  Redistribution and use of this code or any derivative works are permitted
  *  provided that the following conditions are met:
diff --git a/core/system.h b/core/system.h
index d7ca95f..a9c0945 100644
--- a/core/system.h
+++ b/core/system.h
@@ -5,7 +5,7 @@
  *  Support for 16-bit & 8-bit hardware modes
  *
  *  Copyright (C) 1998-2003  Charles Mac Donald (original code)
- *  Copyright (C) 2007-2021  Eke-Eke (Genesis Plus GX)
+ *  Copyright (C) 2007-2022  Eke-Eke (Genesis Plus GX)
  *
  *  Redistribution and use of this code or any derivative works are permitted
  *  provided that the following conditions are met:
@@ -45,17 +45,18 @@
 #include "blip_buf.h"
 
 /* Supported hardware models */
-#define SYSTEM_SG         0x10
-#define SYSTEM_SGII       0x11
-#define SYSTEM_MARKIII    0x12
-#define SYSTEM_SMS        0x20
-#define SYSTEM_SMS2       0x21
-#define SYSTEM_GG         0x40
-#define SYSTEM_GGMS       0x41
-#define SYSTEM_MD         0x80
-#define SYSTEM_PBC        0x81
-#define SYSTEM_PICO       0x82
-#define SYSTEM_MCD        0x84
+#define SYSTEM_SG           0x01
+#define SYSTEM_SGII         0x02
+#define SYSTEM_SGII_RAM_EXT 0x03
+#define SYSTEM_MARKIII      0x10
+#define SYSTEM_SMS          0x20
+#define SYSTEM_SMS2         0x21
+#define SYSTEM_GG           0x40
+#define SYSTEM_GGMS         0x41
+#define SYSTEM_MD           0x80
+#define SYSTEM_PBC          0x81
+#define SYSTEM_PICO         0x82
+#define SYSTEM_MCD          0x84
 
 /* NTSC & PAL Master Clock frequencies */
 #define MCLOCK_NTSC 53693175
diff --git a/core/vdp_ctrl.c b/core/vdp_ctrl.c
index a91757e..be7957c 100644
--- a/core/vdp_ctrl.c
+++ b/core/vdp_ctrl.c
@@ -362,6 +362,7 @@ void vdp_reset(void)
   {
     case SYSTEM_SG:
     case SYSTEM_SGII:
+    case SYSTEM_SGII_RAM_EXT:
     {
       /* SG-1000 (TMS99xx) or SG-1000 II (315-5066) VDP */
       vdp_z80_data_w = vdp_z80_data_w_sg;
diff --git a/core/vdp_render.c b/core/vdp_render.c
index 070ac18..7aee11e 100644
--- a/core/vdp_render.c
+++ b/core/vdp_render.c
@@ -1036,6 +1036,7 @@ void color_update_m4(int index, unsigned int data)
 
     case SYSTEM_SG:
     case SYSTEM_SGII:
+    case SYSTEM_SGII_RAM_EXT:
     {
       /* Fixed TMS99xx palette */
       if (index & 0x0F)
@@ -4748,7 +4749,7 @@ void render_line(int line)
     /* Left-most column blanking */
     if (reg[0] & 0x20)
     {
-      if (system_hw > SYSTEM_SGII)
+      if (system_hw >= SYSTEM_MARKIII)
       {
         memset(&linebuf[0][0x20], 0x40, 8);
       }
diff --git a/gcw0/config.c b/gcw0/config.c
index c92e6ba..c5a10d1 100644
--- a/gcw0/config.c
+++ b/gcw0/config.c
@@ -57,7 +57,7 @@ void set_config_defaults(void)
     config.mono           = 0;
 
     /* system options */
-    config.system         = 0; /* = AUTO (or SYSTEM_SG, SYSTEM_MARKIII, SYSTEM_SMS, SYSTEM_SMS2, SYSTEM_GG, SYSTEM_MD) */
+    config.system         = 0; /* = AUTO (or SYSTEM_SG, SYSTEM_SGII, SYSTEM_SGII_RAM_EXT, SYSTEM_MARKIII, SYSTEM_SMS, SYSTEM_SMS2, SYSTEM_GG, SYSTEM_MD) */
     config.region_detect  = 0; /* = AUTO (1 = USA, 2 = EUROPE, 3 = JAPAN/NTSC, 4 = JAPAN/PAL) */
     config.vdp_mode       = 0; /* = AUTO (1 = NTSC, 2 = PAL) */
     config.master_clock   = 0; /* = AUTO (1 = NTSC, 2 = PAL) */
diff --git a/gcw0/main.c b/gcw0/main.c
index 06ebe10..3ffe435 100644
--- a/gcw0/main.c
+++ b/gcw0/main.c
@@ -960,7 +960,7 @@ static int gcw0menu(void)
             SDL_FreeSurface(tempbgSurface);
             SDL_FreeSurface(bgSurface);
         }
-        else if ( (system_hw == SYSTEM_SG)      || (system_hw == SYSTEM_SGII) ) //SG-1000 I&II
+        else if ( (system_hw == SYSTEM_SG)|| (system_hw == SYSTEM_SGII) || (system_hw == SYSTEM_SGII_RAM_EXT) ) //SG-1000 I&II
         {
             SDL_Surface *tempbgSurface;
             SDL_Surface *bgSurface;
diff --git a/gcw0/utils.c b/gcw0/utils.c
index 67ac55a..a350aef 100644
--- a/gcw0/utils.c
+++ b/gcw0/utils.c
@@ -119,9 +119,9 @@ char* get_save_directory(void) {
    
     char pathname[MAXPATHLEN];
     
-	if(system_hw <= SYSTEM_MARKIII){
+	if(system_hw < SYSTEM_MARKIII){
 		system_dir = "/saves/sg";
-	} else if (system_hw > SYSTEM_MARKIII && system_hw <= SYSTEM_SMS2) {
+	} else if (system_hw >= SYSTEM_MARKIII && system_hw <= SYSTEM_SMS2) {
 		system_dir = "/saves/ms";
 	} else if (system_hw > SYSTEM_SMS2 && system_hw <= SYSTEM_GGMS) {
 		system_dir = "/saves/gg";
diff --git a/gx/docs/README.doc b/gx/docs/README.doc
index 3c7df87..7242fd4 100644
Binary files a/gx/docs/README.doc and b/gx/docs/README.doc differ
diff --git a/gx/docs/README.pdf b/gx/docs/README.pdf
index 4379dfb..e0105e9 100644
Binary files a/gx/docs/README.pdf and b/gx/docs/README.pdf differ
diff --git a/gx/gui/menu.c b/gx/gui/menu.c
index 8118735..0271a27 100644
--- a/gx/gui/menu.c
+++ b/gx/gui/menu.c
@@ -1300,6 +1300,8 @@ static void systemmenu ()
     sprintf (items[0].text, "System: SG-1000");
   else if (config.system == SYSTEM_SGII)
     sprintf (items[0].text, "System: SG-1000 II");
+  else if (config.system == SYSTEM_SGII_RAM_EXT)
+    sprintf (items[0].text, "System: SG-1000 + RAM EXT.");
   else if (config.system == SYSTEM_MARKIII)
     sprintf (items[0].text, "System: MARK-III");
   else if (config.system == SYSTEM_SMS)
@@ -1416,6 +1418,12 @@ static void systemmenu ()
           if (system_hw) system_hw = SYSTEM_SGII;
         }
         else if (config.system == SYSTEM_SGII)
+        {
+          config.system = SYSTEM_SGII_RAM_EXT;
+          sprintf (items[0].text, "System: SG-1000 + RAM EXT.");
+          if (system_hw) system_hw = SYSTEM_SGII_RAM_EXT;
+        }
+        else if (config.system == SYSTEM_SGII_RAM_EXT)
         {
           config.system = SYSTEM_MARKIII;
           sprintf (items[0].text, "System: MARK-III");
diff --git a/libretro/libretro.c b/libretro/libretro.c
index 653ebb9..6c62e4f 100644
--- a/libretro/libretro.c
+++ b/libretro/libretro.c
@@ -1292,6 +1292,8 @@ static void check_variables(bool first_run)
       config.system = SYSTEM_SG;
     else if (var.value && !strcmp(var.value, "sg-1000 II"))
       config.system = SYSTEM_SGII;
+    else if (var.value && !strcmp(var.value, "sg-1000 II + ram ext."))
+      config.system = SYSTEM_SGII_RAM_EXT;
     else if (var.value && !strcmp(var.value, "mark-III"))
       config.system = SYSTEM_MARKIII;
     else if (var.value && !strcmp(var.value, "master system"))
@@ -3423,7 +3425,11 @@ size_t retro_get_memory_size(unsigned id)
         }
       }
       case RETRO_MEMORY_SYSTEM_RAM:
-         if (system_hw == SYSTEM_SMS || system_hw == SYSTEM_SMS2 || system_hw == SYSTEM_GG || system_hw == SYSTEM_GGMS)
+         if (system_hw == SYSTEM_SG)
+            return 0x00400;
+         else if (system_hw == SYSTEM_SGII)
+            return 0x00800;
+         else if (system_hw == SYSTEM_SGII_RAM_EXT || system_hw == SYSTEM_SMS || system_hw == SYSTEM_SMS2 || system_hw == SYSTEM_GG || system_hw == SYSTEM_GGMS || system_hw == SYSTEM_PBC)
             return 0x02000;
          else
             return 0x10000;
diff --git a/libretro/libretro_core_options.h b/libretro/libretro_core_options.h
index 882fef0..c843955 100644
--- a/libretro/libretro_core_options.h
+++ b/libretro/libretro_core_options.h
@@ -102,14 +102,15 @@ struct retro_core_option_v2_definition option_defs_us[] = {
       NULL,
       "system",
       {
-         { "auto",                 "Auto"               },
-         { "sg-1000",              "SG-1000"            },
-         { "sg-1000 II",           "SG-1000 II"         },
-         { "mark-III",             "Mark III"           },
-         { "master system",        "Master System"      },
-         { "master system II",     "Master System II"   },
-         { "game gear",            "Game Gear"          },
-         { "mega drive / genesis", "Mega Drive/Genesis" },
+         { "auto",                 "Auto"                 },
+         { "sg-1000",              "SG-1000"              },
+         { "sg-1000 II",           "SG-1000 II"           },
+         { "sg-1000 II + ram ext.","SG-1000 II + RAM Ext."},
+         { "mark-III",             "Mark III"             },
+         { "master system",        "Master System"        },
+         { "master system II",     "Master System II"     },
+         { "game gear",            "Game Gear"            },
+         { "mega drive / genesis", "Mega Drive/Genesis"   },
          { NULL, NULL },
       },
       "auto"
diff --git a/psp2/config.c b/psp2/config.c
index f80c2c3..f1b74d3 100644
--- a/psp2/config.c
+++ b/psp2/config.c
@@ -26,7 +26,7 @@ void set_config_defaults(void)
   config.mono           = 0;
 
   /* system options */
-  config.system         = 0; /* = AUTO (or SYSTEM_SG, SYSTEM_MARKIII, SYSTEM_SMS, SYSTEM_SMS2, SYSTEM_GG, SYSTEM_MD) */
+  config.system         = 0; /* = AUTO (or SYSTEM_SG, SYSTEM_SGII, SYSTEM_SGII_RAM_EXT, SYSTEM_MARKIII, SYSTEM_SMS, SYSTEM_SMS2, SYSTEM_GG, SYSTEM_MD) */
   config.region_detect  = 0; /* = AUTO (1 = USA, 2 = EUROPE, 3 = JAPAN/NTSC, 4 = JAPAN/PAL) */
   config.vdp_mode       = 0; /* = AUTO (1 = NTSC, 2 = PAL) */
   config.master_clock   = 0; /* = AUTO (1 = NTSC, 2 = PAL) */
diff --git a/sdl/config.c b/sdl/config.c
index 5e2cf72..223d720 100644
--- a/sdl/config.c
+++ b/sdl/config.c
@@ -29,7 +29,7 @@ void set_config_defaults(void)
   config.mono           = 0;
 
   /* system options */
-  config.system         = 0; /* = AUTO (or SYSTEM_SG, SYSTEM_MARKIII, SYSTEM_SMS, SYSTEM_SMS2, SYSTEM_GG, SYSTEM_MD) */
+  config.system         = 0; /* = AUTO (or SYSTEM_SG, SYSTEM_SGII, SYSTEM_SGII_RAM_EXT, SYSTEM_MARKIII, SYSTEM_SMS, SYSTEM_SMS2, SYSTEM_GG, SYSTEM_MD) */
   config.region_detect  = 0; /* = AUTO (1 = USA, 2 = EUROPE, 3 = JAPAN/NTSC, 4 = JAPAN/PAL) */
   config.vdp_mode       = 0; /* = AUTO (1 = NTSC, 2 = PAL) */
   config.master_clock   = 0; /* = AUTO (1 = NTSC, 2 = PAL) */