diff --git a/HISTORY.txt b/HISTORY.txt
index 9cea7fb..f30a2cf 100644
--- a/HISTORY.txt
+++ b/HISTORY.txt
@@ -56,6 +56,7 @@ Genesis Plus GX 1.7.5 (xx/xx/xxxx) (Eke-Eke)
 * added support for Everdrive extended SSF mapper
 * added (very basic) emulation of Flashkit MD hardware
 * added emulation of Micro Machines USA on-board TMSS bypass logic hardware
+* added SRAM support for games larger than 8MB
 * improved console region auto-detection for a few PAL-only games (The Smurfs Travel the World & Williams Arcade's Greatest Hits)
 * improved I2C EEPROM boards emulation accuracy
 * improved SVP memory handlers accuracy (fixes Virtua Racing debug mode)
diff --git a/core/cart_hw/areplay.c b/core/cart_hw/areplay.c
index 73b16a4..b066716 100644
--- a/core/cart_hw/areplay.c
+++ b/core/cart_hw/areplay.c
@@ -2,7 +2,7 @@
  *  Genesis Plus
  *  Action Replay / Pro Action Replay emulation
  *
- *  Copyright (C) 2009-2014  Eke-Eke (Genesis Plus GX)
+ *  Copyright (C) 2009-2021  Eke-Eke (Genesis Plus GX)
  *
  *  Redistribution and use of this code or any derivative works are permitted
  *  provided that the following conditions are met:
@@ -63,10 +63,10 @@ void areplay_init(void)
   
   memset(&action_replay,0,sizeof(action_replay));
 
-  /* store Action replay ROM (max. 128k) & RAM (64k) above cartridge ROM + SRAM area */
-  if (cart.romsize > 0x810000) return;
-  action_replay.rom = cart.rom + 0x810000;
-  action_replay.ram = cart.rom + 0x830000;
+  /* store Action replay ROM (max. 128KB) & RAM (64KB) above cartridge ROM (max. 8MB) */
+  if (cart.romsize > 0x800000) return;
+  action_replay.rom = cart.rom + 0x800000;
+  action_replay.ram = cart.rom + 0x820000;
 
   /* try to load Action Replay ROM file */
   size = load_archive(AR_ROM, action_replay.rom, 0x20000, NULL);
diff --git a/core/cart_hw/areplay.h b/core/cart_hw/areplay.h
index d4e8f26..3b4f2a9 100644
--- a/core/cart_hw/areplay.h
+++ b/core/cart_hw/areplay.h
@@ -2,7 +2,7 @@
  *  Genesis Plus
  *  DATEL Action Replay / Pro Action Replay emulation
  *
- *  Copyright (C) 2009-2014  Eke-Eke (Genesis Plus GX)
+ *  Copyright (C) 2009-2021  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/cart_hw/ggenie.c b/core/cart_hw/ggenie.c
index 8fc3b23..f9fdbf7 100644
--- a/core/cart_hw/ggenie.c
+++ b/core/cart_hw/ggenie.c
@@ -2,7 +2,7 @@
  *  Genesis Plus
  *  Game Genie Hardware emulation
  *
- *  Copyright (C) 2009-2014  Eke-Eke (Genesis Plus GX)
+ *  Copyright (C) 2009-2021  Eke-Eke (Genesis Plus GX)
  *
  *  Based on documentation from Charles McDonald
  *  (http://cgfm2.emuviews.com/txt/genie.txt)
@@ -61,9 +61,9 @@ void ggenie_init(void)
 {  
   memset(&ggenie,0,sizeof(ggenie));
 
-  /* Store Game Genie ROM (32k) above cartridge ROM + SRAM area */
-  if (cart.romsize > 0x810000) return;
-  ggenie.rom = cart.rom + 0x810000;
+  /* Store Game Genie ROM (32KB) above cartridge ROM (max. 8MB) */
+  if (cart.romsize > 0x800000) return;
+  ggenie.rom = cart.rom + 0x800000;
 
   /* Try to load Game Genie ROM file */
   if (load_archive(GG_ROM, ggenie.rom, 0x8000, NULL) > 0)
diff --git a/core/cart_hw/ggenie.h b/core/cart_hw/ggenie.h
index a67f007..b61f611 100644
--- a/core/cart_hw/ggenie.h
+++ b/core/cart_hw/ggenie.h
@@ -2,7 +2,7 @@
  *  Genesis Plus
  *  Game Genie Hardware emulation
  *
- *  Copyright (C) 2009-2014  Eke-Eke (Genesis Plus GX)
+ *  Copyright (C) 2009-2021  Eke-Eke (Genesis Plus GX)
  *
  *  Based on documentation from Charles McDonald
  *  (http://cgfm2.emuviews.com/txt/genie.txt)
diff --git a/core/cart_hw/md_cart.c b/core/cart_hw/md_cart.c
index cc5a445..5c7602b 100644
--- a/core/cart_hw/md_cart.c
+++ b/core/cart_hw/md_cart.c
@@ -478,39 +478,39 @@ void md_cart_init(void)
 
     case TYPE_SK:
     {
-      /* store S&K ROM above cartridge ROM (and before backup memory) */
-      if (cart.romsize > 0x600000) break;
+      /* store Sonic & Knuckles ROM files after cartridge ROM area */
+      if (cart.romsize > 0x400000) break;
 
-      /* try to load Sonic & Knuckles ROM file (2 MB) */
-      if (load_archive(SK_ROM, cart.rom + 0x600000, 0x200000, NULL) == 0x200000)
+      /* try to load Sonic & Knuckles ROM file (2MB) */
+      if (load_archive(SK_ROM, cart.rom + 0x400000, 0x200000, NULL) == 0x200000)
       {
         /* check ROM header */
-        if (!memcmp(cart.rom + 0x600000 + 0x120, "SONIC & KNUCKLES",16))
+        if (!memcmp(cart.rom + 0x400000 + 0x120, "SONIC & KNUCKLES",16))
         {
-          /* try to load Sonic 2 & Knuckles UPMEM ROM (256 KB) */
-          if (load_archive(SK_UPMEM, cart.rom + 0x900000, 0x40000, NULL) == 0x40000)
+          /* try to load Sonic 2 & Knuckles upmem ROM file (256KB) */
+          if (load_archive(SK_UPMEM, cart.rom + 0x600000, 0x40000, NULL) == 0x40000)
           {
             /* $000000-$1FFFFF is mapped to S&K ROM */
             for (i=0x00; i<0x20; i++)
             {
-              m68k.memory_map[i].base = cart.rom + 0x600000 + (i << 16);
+              m68k.memory_map[i].base = cart.rom + 0x400000 + (i << 16);
             }
 
 #ifdef LSB_FIRST
             for (i=0; i<0x200000; i+=2)
             {
               /* Byteswap ROM */
-              uint8 temp = cart.rom[i + 0x600000];
-              cart.rom[i + 0x600000] = cart.rom[i + 0x600000 + 1];
-              cart.rom[i + 0x600000 + 1] = temp;
+              uint8 temp = cart.rom[i + 0x400000];
+              cart.rom[i + 0x400000] = cart.rom[i + 0x400000 + 1];
+              cart.rom[i + 0x400000 + 1] = temp;
             }
 
             for (i=0; i<0x40000; i+=2)
             {
               /* Byteswap ROM */
-              uint8 temp = cart.rom[i + 0x900000];
-              cart.rom[i + 0x900000] = cart.rom[i + 0x900000 + 1];
-              cart.rom[i + 0x900000 + 1] = temp;
+              uint8 temp = cart.rom[i + 0x600000];
+              cart.rom[i + 0x600000] = cart.rom[i + 0x600000 + 1];
+              cart.rom[i + 0x600000 + 1] = temp;
             }
 #endif
             cart.special |= HW_LOCK_ON;
@@ -569,16 +569,16 @@ void md_cart_init(void)
   /* Realtec mapper */
   if (cart.hw.realtec)
   {
-    /* 8k BOOT ROM */
+    /* copy 8KB Boot ROM after cartridge ROM area */
     for (i=0; i<8; i++)
     {
-      memcpy(cart.rom + 0x900000 + i*0x2000, cart.rom + 0x7e000, 0x2000);
+      memcpy(cart.rom + 0x400000 + i*0x2000, cart.rom + 0x7e000, 0x2000);
     }
 
-    /* BOOT ROM is mapped to $000000-$3FFFFF */
+    /* Boot ROM (8KB mirrored) is mapped to $000000-$3FFFFF */
     for (i=0x00; i<0x40; i++)
     {
-      m68k.memory_map[i].base = cart.rom + 0x900000;
+      m68k.memory_map[i].base = cart.rom + 0x400000;
     }
   }
 
@@ -953,12 +953,12 @@ static void mapper_sega_w(uint32 data)
     }
 
     /* S&K lock-on chip */
-    if ((cart.special & HW_LOCK_ON) && (config.lock_on == TYPE_SK))
+    if (cart.special & HW_LOCK_ON)
     {
-      /* S2K upmem chip mapped to $300000-$3fffff (256K mirrored) */
+      /* S2K upmem chip mapped to $300000-$3fffff (256KB mirrored) */
       for (i=0x30; i<0x40; i++)
       {
-        m68k.memory_map[i].base = (cart.rom + 0x900000) + ((i & 3) << 16);
+        m68k.memory_map[i].base = (cart.rom + 0x600000) + ((i & 3) << 16);
       }
     }
   }
diff --git a/core/cart_hw/sram.c b/core/cart_hw/sram.c
index 58ef404..4abc91e 100644
--- a/core/cart_hw/sram.c
+++ b/core/cart_hw/sram.c
@@ -2,7 +2,7 @@
  *  Genesis Plus
  *  Backup RAM support
  *
- *  Copyright (C) 2007-2020  Eke-Eke (Genesis Plus GX)
+ *  Copyright (C) 2007-2021  Eke-Eke (Genesis Plus GX)
  *
  *  Redistribution and use of this code or any derivative works are permitted
  *  provided that the following conditions are met:
@@ -61,11 +61,8 @@ T_SRAM sram;
  ****************************************************************************/
 void sram_init()
 {
-  memset(&sram, 0, sizeof (T_SRAM));
-
-  /* backup RAM data is stored above cartridge ROM area, at $800000-$80FFFF (max. 64K) */
-  if (cart.romsize > 0x800000) return;
-  sram.sram = cart.rom + 0x800000;
+  /* disable Backup RAM by default */
+  sram.detected = sram.on = sram.custom = sram.start = sram.end = 0;
 
   /* initialize Backup RAM */
   if (strstr(rominfo.international,"Sonic 1 Remastered"))
diff --git a/core/cart_hw/sram.h b/core/cart_hw/sram.h
index 3b505c5..e33f6e4 100644
--- a/core/cart_hw/sram.h
+++ b/core/cart_hw/sram.h
@@ -2,7 +2,7 @@
  *  Genesis Plus
  *  Backup RAM support
  *
- *  Copyright (C) 2007-2020  Eke-Eke (Genesis Plus GX)
+ *  Copyright (C) 2007-2021  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 +47,7 @@ typedef struct
   uint32 start;
   uint32 end;
   uint32 crc;
-  uint8 *sram;
+  uint8 sram[0x10000];
 } T_SRAM;
 
 /* Function prototypes */
diff --git a/core/cd_hw/cd_cart.c b/core/cd_hw/cd_cart.c
index 09e84df..a380bd2 100644
--- a/core/cd_hw/cd_cart.c
+++ b/core/cd_hw/cd_cart.c
@@ -2,7 +2,7 @@
  *  Genesis Plus
  *  CD compatible ROM/RAM cartridge support
  *
- *  Copyright (C) 2012-2016 Eke-Eke (Genesis Plus GX)
+ *  Copyright (C) 2012-2021 Eke-Eke (Genesis Plus GX)
  *
  *  Redistribution and use of this code or any derivative works are permitted
  *  provided that the following conditions are met:
@@ -38,7 +38,6 @@
 
 #include "shared.h"
 
-
 /*--------------------------------------------------------------------------*/
 /* backup RAM cartridge (max. 512KB)                                        */
 /*--------------------------------------------------------------------------*/
diff --git a/core/cd_hw/cd_cart.h b/core/cd_hw/cd_cart.h
index 6ee7cad..a0e7482 100644
--- a/core/cd_hw/cd_cart.h
+++ b/core/cd_hw/cd_cart.h
@@ -2,7 +2,7 @@
  *  Genesis Plus
  *  CD compatible ROM/RAM cartridge support
  *
- *  Copyright (C) 2012-2016 Eke-Eke (Genesis Plus GX)
+ *  Copyright (C) 2012-2021 Eke-Eke (Genesis Plus GX)
  *
  *  Redistribution and use of this code or any derivative works are permitted
  *  provided that the following conditions are met:
@@ -41,7 +41,7 @@
 typedef struct 
 {
   uint8 reserved[0x80];  /* reserved for ROM cartridge infos (see md_cart.h) */
-  uint8 area[0x840000];  /* cartridge ROM/RAM area (max. 8MB ROM + 64KB backup memory + Pro Action Replay 128KB ROM / 64KB RAM) */
+  uint8 area[0x830000];  /* cartridge ROM/RAM area (max. 8MB ROM + Pro Action Replay 128KB ROM / 64KB RAM) */
   uint8 boot;            /* cartridge boot mode (0x00: boot from CD with ROM/RAM cartridge enabled, 0x40: boot from ROM cartridge with CD enabled) */
   uint8 id;              /* RAM cartridge ID (related to RAM size, 0 if disabled) */
   uint8 prot;            /* RAM cartridge write protection */