diff --git a/retro-core/components/nofrendo/nes/mem.c b/retro-core/components/nofrendo/nes/mem.c
index 10ce5d9e8..dc2f29b9c 100644
--- a/retro-core/components/nofrendo/nes/mem.c
+++ b/retro-core/components/nofrendo/nes/mem.c
@@ -54,17 +54,23 @@ static const mem_write_handler_t write_handlers[] =
 /* Set 2KB memory page */
 void mem_setpage(uint32 page, uint8 *ptr)
 {
-   ASSERT(page < 32);
-   ASSERT(ptr);
+   if (page >= MEM_PAGECOUNT)
+   {
+      MESSAGE_ERROR("Invalid page #%d (max: %d) !\n", page, MEM_PAGECOUNT);
+      return;
+   }
 
-   mem.pages[page] = ptr - (page * MEM_PAGESIZE);
+   if (ptr)
+      mem.pages[page] = ptr - (page * MEM_PAGESIZE);
+   else
+      mem.pages[page] = NULL;
 
-   if (!MEM_PAGE_HAS_HANDLERS(mem.pages_read[page]))
+   if (mem.pages_read[page] != MEM_PAGE_HAS_HANDLERS)
    {
       mem.pages_read[page] = mem.pages[page];
    }
 
-   if (!MEM_PAGE_HAS_HANDLERS(mem.pages_write[page]))
+   if (mem.pages_write[page] != MEM_PAGE_HAS_HANDLERS)
    {
       mem.pages_write[page] = mem.pages[page];
    }
@@ -73,16 +79,16 @@ void mem_setpage(uint32 page, uint8 *ptr)
 /* Get 2KB memory page */
 uint8 *mem_getpage(uint32 page)
 {
-   ASSERT(page < 32);
-
-   uint8 *page_ptr = mem.pages[page];
-
-   if (MEM_PAGE_IS_VALID_PTR(page_ptr))
+   if (page >= MEM_PAGECOUNT)
    {
-      return page_ptr + (page * MEM_PAGESIZE);
+      MESSAGE_ERROR("Invalid page #%d (max: %d) !\n", page, MEM_PAGECOUNT);
+      return NULL;
    }
 
-   return page_ptr;
+   if (!mem.pages[page])
+      return NULL;
+
+   return mem.pages[page] + (page * MEM_PAGESIZE);
 }
 
 /* read a byte of 6502 memory space */
@@ -91,7 +97,7 @@ IRAM_ATTR uint8 mem_getbyte(uint32 address)
    uint8 *page = mem.pages_read[address >> MEM_PAGESHIFT];
 
    /* Special memory handlers */
-   if (MEM_PAGE_HAS_HANDLERS(page))
+   if (page == MEM_PAGE_HAS_HANDLERS)
    {
       for (mem_read_handler_t *mr = mem.read_handlers; mr->read_func != NULL; mr++)
       {
@@ -102,16 +108,13 @@ IRAM_ATTR uint8 mem_getbyte(uint32 address)
    }
 
    /* Unmapped region */
-   if (page == NULL)
+   if (page == MEM_PAGE_NOT_MAPPED)
    {
       MESSAGE_DEBUG("Read unmapped region: $%4X\n", address);
       return 0xFF;
    }
-   /* Paged memory */
-   else
-   {
-      return page[address];
-   }
+
+   return page[address];
 }
 
 /* write a byte of data to 6502 memory space */
@@ -120,7 +123,7 @@ IRAM_ATTR void mem_putbyte(uint32 address, uint8 value)
    uint8 *page = mem.pages_write[address >> MEM_PAGESHIFT];
 
    /* Special memory handlers */
-   if (MEM_PAGE_HAS_HANDLERS(page))
+   if (page == MEM_PAGE_HAS_HANDLERS)
    {
       for (mem_write_handler_t *mw = mem.write_handlers; mw->write_func != NULL; mw++)
       {
@@ -134,15 +137,13 @@ IRAM_ATTR void mem_putbyte(uint32 address, uint8 value)
    }
 
    /* Unmapped region */
-   if (page == NULL)
+   if (page == MEM_PAGE_NOT_MAPPED)
    {
       MESSAGE_DEBUG("Write to unmapped region: $%2X to $%4X\n", address, value);
+      return;
    }
-   /* Paged memory */
-   else
-   {
-      page[address] = value;
-   }
+
+   page[address] = value;
 }
 
 IRAM_ATTR uint32 mem_getword(uint32 address)
@@ -154,12 +155,17 @@ void mem_reset(void)
 {
    memset(&mem, 0, sizeof(mem));
 
-   mem_setpage(0, mem.ram);
+   mem_setpage(0, mem.ram); // $000 - $7FF
    mem_setpage(1, mem.ram); // $800 - $FFF mirror
    mem_setpage(2, mem.ram); // $1000 - $07FF mirror
    mem_setpage(3, mem.ram); // $1800 - $1FFF mirror
 
-   int num_read_handlers = 0, num_write_handlers = 0;
+   for (size_t i = 4; i < MEM_PAGECOUNT; ++i)
+   {
+      mem_setpage(i, MEM_PAGE_NOT_MAPPED);
+   }
+
+   size_t num_read_handlers = 0, num_write_handlers = 0;
    mapper_t *mapper = nes_getptr()->mapper;
 
    // NES cartridge handlers
@@ -189,13 +195,13 @@ void mem_reset(void)
    for (mem_read_handler_t *mr = mem.read_handlers; mr->read_func != NULL; mr++)
    {
       for (int i = mr->min_range; i < mr->max_range; i++)
-         mem.pages_read[i >> MEM_PAGESHIFT] = MEM_PAGE_USE_HANDLERS;
+         mem.pages_read[i >> MEM_PAGESHIFT] = MEM_PAGE_HAS_HANDLERS;
    }
 
    for (mem_write_handler_t *mw = mem.write_handlers; mw->write_func != NULL; mw++)
    {
       for (int i = mw->min_range; i < mw->max_range; i++)
-         mem.pages_write[i >> MEM_PAGESHIFT] = MEM_PAGE_USE_HANDLERS;
+         mem.pages_write[i >> MEM_PAGESHIFT] = MEM_PAGE_HAS_HANDLERS;
    }
 
    ASSERT(num_read_handlers <= MEM_HANDLERS_MAX);
diff --git a/retro-core/components/nofrendo/nes/mem.h b/retro-core/components/nofrendo/nes/mem.h
index 2229c9911..62413001e 100644
--- a/retro-core/components/nofrendo/nes/mem.h
+++ b/retro-core/components/nofrendo/nes/mem.h
@@ -32,12 +32,8 @@
 #define MEM_RAMSIZE   0x800
 
 // This is kind of a hack, but for speed...
-#define MEM_PAGE_USE_HANDLERS ((uint8*)1)
-#define MEM_PAGE_READ_ONLY    ((uint8*)2)
-#define MEM_PAGE_WRITE_ONLY   ((uint8*)3)
-
-#define MEM_PAGE_HAS_HANDLERS(page) ((page) == MEM_PAGE_USE_HANDLERS)
-#define MEM_PAGE_IS_VALID_PTR(page) ((page) > ((uint8*)100))
+#define MEM_PAGE_HAS_HANDLERS ((uint8*)1)
+#define MEM_PAGE_NOT_MAPPED   NULL
 
 #define MEM_HANDLERS_MAX     32
 
diff --git a/retro-core/components/nofrendo/nes/mmc.c b/retro-core/components/nofrendo/nes/mmc.c
index 31cc14ad8..90873cd78 100644
--- a/retro-core/components/nofrendo/nes/mmc.c
+++ b/retro-core/components/nofrendo/nes/mmc.c
@@ -30,6 +30,7 @@ static rom_t *cart;
 /* PRG-ROM/RAM bankswitching */
 void mmc_bankprg(unsigned size, unsigned address, int bank, uint8 *base)
 {
+   // ASSERT(size == 8 || size == 16 || size == 32);
    size_t banks = 16;
 
    // if (base == PRG_ANY)
@@ -46,40 +47,31 @@ void mmc_bankprg(unsigned size, unsigned address, int bank, uint8 *base)
       banks = cart->prg_ram_banks;
    }
 
-   if (base == NULL)
-   {
-      MESSAGE_ERROR("MMC: Invalid pointer! Addr: $%04X Bank: %d Size: %d\n", address, bank, size);
-      abort();
-   }
-
-   switch (size)
-   {
-   case 8:
-      base += ((bank >= 0 ? bank : (banks) + bank) % (banks)) << 13;
-      break;
-
-   case 16:
-      base += ((bank >= 0 ? bank : (banks / 2) + bank) % (banks / 2)) << 14;
-      break;
+   banks /= (size / 8);
 
-   case 32:
-      base += ((bank >= 0 ? bank : (banks / 4) + bank) % (banks / 4)) << 15;
-      break;
+   if (bank < 0)
+      bank += banks;
 
-   default:
-      MESSAGE_ERROR("MMC: Invalid bank size! Addr: $%04X Bank: %d Size: %d\n", address, bank, size);
-      abort();
+   if (base == NULL || banks == 0 || bank < 0) // || bank > banks)
+   {
+      MESSAGE_ERROR("MMC: Bogus PRG mapping! Address: $%04X, Size: %dKB, Bank: %d, Banks: %d, Base: %p\n",
+         address, size, bank, banks, base);
+      return;
    }
 
-   for (int i = 0; i < (size * 0x400 / MEM_PAGESIZE); i++)
+   bank %= banks;
+   base += bank * (size * 1024);
+
+   for (size_t i = 0, num = (size * 1024 / MEM_PAGESIZE); i < num; ++i)
    {
-      mem_setpage((address >> MEM_PAGESHIFT) + i, base + i * MEM_PAGESIZE);
+      mem_setpage((address >> MEM_PAGESHIFT) + i, &base[i * MEM_PAGESIZE]);
    }
 }
 
 /* CHR-ROM/RAM bankswitching */
 void mmc_bankchr(unsigned size, unsigned address, int bank, uint8 *base)
 {
+   // ASSERT(size == 1 || size == 2 || size == 4 || size == 8);
    size_t banks = 128;
 
    if (base == CHR_ANY)
@@ -96,32 +88,22 @@ void mmc_bankchr(unsigned size, unsigned address, int bank, uint8 *base)
       banks = cart->chr_ram_banks;
    }
 
-   switch (size)
+   banks *= (8 / size);
+
+   if (bank < 0)
+      bank += banks;
+
+   if (base == NULL || banks == 0 || bank < 0) // || bank > banks)
    {
-   case 1:
-      bank = (bank >= 0 ? bank : (banks * 8) + bank) % (banks * 8);
-      ppu_setpage(1, address >> 10, &base[bank << 10] - address);
-      break;
-
-   case 2:
-      bank = (bank >= 0 ? bank : (banks * 4) + bank) % (banks * 4);
-      ppu_setpage(2, address >> 10, &base[bank << 11] - address);
-      break;
-
-   case 4:
-      bank = (bank >= 0 ? bank : (banks * 2) + bank) % (banks * 2);
-      ppu_setpage(4, address >> 10, &base[bank << 12] - address);
-      break;
-
-   case 8:
-      bank = (bank >= 0 ? bank : (banks) + bank) % (banks);
-      ppu_setpage(8, 0, &base[bank << 13]);
-      break;
-
-   default:
-      MESSAGE_ERROR("MMC: Invalid CHR bank size %d\n", size);
-      abort();
+      MESSAGE_ERROR("MMC: Bogus CHR mapping! Address: $%04X, Size: %dKB, Bank: %d, Banks: %d, Base: %p\n",
+         address, size, bank, banks, base);
+      return;
    }
+
+   bank %= banks;
+   base += bank * (size * 1024);
+
+   ppu_setpage(size, address >> 10, base - address);
 }
 
 /* Mapper initialization routine */
diff --git a/retro-core/components/nofrendo/nes/ppu.c b/retro-core/components/nofrendo/nes/ppu.c
index 3d976cfb7..2db6ba862 100644
--- a/retro-core/components/nofrendo/nes/ppu.c
+++ b/retro-core/components/nofrendo/nes/ppu.c
@@ -337,7 +337,7 @@ IRAM_ATTR void ppu_write(uint32 address, uint8 value)
    }
 }
 
-void ppu_setopt(ppu_option_t n, uint8_t val)
+void ppu_setopt(ppu_option_t n, int val)
 {
    // Some options need special care
    switch (n)
@@ -349,7 +349,7 @@ void ppu_setopt(ppu_option_t n, uint8_t val)
    ppu.options[n] = val;
 }
 
-uint8_t ppu_getopt(ppu_option_t n)
+int ppu_getopt(ppu_option_t n)
 {
    return ppu.options[n];
 }
diff --git a/retro-core/components/nofrendo/nes/ppu.h b/retro-core/components/nofrendo/nes/ppu.h
index 655f30e4e..b58a24ce2 100644
--- a/retro-core/components/nofrendo/nes/ppu.h
+++ b/retro-core/components/nofrendo/nes/ppu.h
@@ -132,7 +132,7 @@ typedef struct
    bool vram_present;
 
    /* Misc runtime options */
-   uint8_t options[16];
+   int options[16];
 } ppu_t;
 
 /* Mirroring / Paging */
@@ -144,12 +144,11 @@ uint8 *ppu_getnametable(int nt);
 
 /* Control */
 ppu_t *ppu_init(void);
-void ppu_refresh(void);
 void ppu_reset(void);
 void ppu_shutdown(void);
 bool ppu_enabled(void);
-void ppu_setopt(ppu_option_t n, uint8_t val);
-uint8_t ppu_getopt(ppu_option_t n);
+void ppu_setopt(ppu_option_t n, int val);
+int ppu_getopt(ppu_option_t n);
 
 void ppu_setlatchfunc(ppu_latchfunc_t func);
 void ppu_setvreadfunc(ppu_vreadfunc_t func);
diff --git a/retro-core/components/nofrendo/nes/rom.c b/retro-core/components/nofrendo/nes/rom.c
index 65215f6a2..6d7122496 100644
--- a/retro-core/components/nofrendo/nes/rom.c
+++ b/retro-core/components/nofrendo/nes/rom.c
@@ -146,7 +146,7 @@ rom_t *rom_loadmem(uint8 *data, size_t size)
          if (entry->prg_ram != rom.prg_ram_banks)
          {
             MESSAGE_WARN("ROM: prg_ram_banks mismatch! (DB: %d, ROM: %d)\n", entry->prg_ram, rom.prg_ram_banks);
-            // rom.prg_rom_banks = entry->prg_ram;
+            // rom.prg_ram_banks = entry->prg_ram;
          }
 
          if (entry->chr_rom > -1 && entry->chr_rom != rom.chr_rom_banks)