@@ -13,6 +13,7 @@ #include "gb/renderers/software.h"
 #include "lr35902/debugger/debugger.h"
 #include "util/memory.h"
 #include "util/patch.h"
+#include "util/vfs.h"
 
 struct GBCore {
 	struct mCore d;
@@ -93,6 +94,16 @@ } else {
 		gb->audio.masterVolume = core->opts.volume;
 	}
 	gb->video.frameskip = core->opts.frameskip;
+
+#if !defined(MINIMAL_CORE) || MINIMAL_CORE < 2
+	struct VFile* bios = 0;
+	if (core->opts.useBios && core->opts.bios) {
+		bios = VFileOpen(core->opts.bios, O_RDONLY);
+	}
+	if (bios) {
+		GBLoadBIOS(gb, bios);
+	}
+#endif
 }
 
 static void _GBCoreDesiredVideoDimensions(struct mCore* core, unsigned* width, unsigned* height) {
@@ -148,11 +159,9 @@ return GBLoadROM(core->board, vf);
 }
 
 static bool _GBCoreLoadBIOS(struct mCore* core, struct VFile* vf, int type) {
-	UNUSED(core);
-	UNUSED(vf);
 	UNUSED(type);
-	// TODO
-	return false;
+	GBLoadBIOS(core->board, vf);
+	return true;
 }
 
 static bool _GBCoreLoadSave(struct mCore* core, struct VFile* vf) {

@@ -88,6 +88,7 @@ return false;
 	}
 	gb->yankedRomSize = 0;
 	gb->memory.rom = gb->pristineRom;
+	gb->memory.romBase = gb->memory.rom;
 	gb->memory.romSize = gb->pristineRomSize;
 	gb->romCrc32 = doCrc32(gb->memory.rom, gb->memory.romSize);
 
@@ -109,6 +110,9 @@ }
 
 void GBUnloadROM(struct GB* gb) {
 	// TODO: Share with GBAUnloadROM
+	if (gb->memory.rom && gb->memory.romBase != gb->memory.rom) {
+		free(gb->memory.romBase);
+	}
 	if (gb->memory.rom && gb->pristineRom != gb->memory.rom) {
 		if (gb->yankedRomSize) {
 			gb->yankedRomSize = 0;
@@ -135,6 +139,10 @@ }
 	gb->memory.sram = 0;
 }
 
+void GBLoadBIOS(struct GB* gb, struct VFile* vf) {
+	gb->biosVf = vf;
+}
+
 void GBApplyPatch(struct GB* gb, struct Patch* patch) {
 	size_t patchedSize = patch->outputSize(patch, gb->memory.romSize);
 	if (!patchedSize) {
@@ -171,31 +179,71 @@
 void GBReset(struct LR35902Core* cpu) {
 	struct GB* gb = (struct GB*) cpu->master;
 
-	const struct GBCartridge* cart = (const struct GBCartridge*) &gb->memory.rom[0x100];
-	if (cart->cgb & 0x80) {
-		gb->model = GB_MODEL_CGB;
-		gb->audio.style = GB_AUDIO_CGB;
-		cpu->a = 0x11;
-		cpu->f.packed = 0x80;
+	if (gb->biosVf) {
+		gb->biosVf->seek(gb->biosVf, 0, SEEK_SET);
+		gb->memory.romBase = malloc(GB_SIZE_CART_BANK0);
+		ssize_t size = gb->biosVf->read(gb->biosVf, gb->memory.romBase, GB_SIZE_CART_BANK0);
+		uint32_t biosCrc = doCrc32(gb->memory.romBase, size);
+		switch (biosCrc) {
+		case 0x59C8598E:
+			gb->model = GB_MODEL_DMG;
+			gb->audio.style = GB_AUDIO_DMG;
+			break;
+		case 0x41884E46:
+			gb->model = GB_MODEL_CGB;
+			gb->audio.style = GB_AUDIO_CGB;
+			break;
+		default:
+			free(gb->memory.romBase);
+			gb->memory.romBase = gb->memory.rom;
+			gb->biosVf = NULL;
+			break;
+		}
+
+		memcpy(&gb->memory.romBase[size], &gb->memory.rom[size], GB_SIZE_CART_BANK0 - size);
+		if (size > 0x100) {
+			memcpy(&gb->memory.romBase[0x100], &gb->memory.rom[0x100], sizeof(struct GBCartridge));
+		}
+
+		cpu->a = 0;
+		cpu->f.packed = 0;
 		cpu->c = 0;
-		cpu->e = 0x08;
+		cpu->e = 0;
 		cpu->h = 0;
-		cpu->l = 0x7C;
-	} else {
-		// TODO: SGB
-		gb->model = GB_MODEL_DMG;
-		gb->audio.style = GB_AUDIO_DMG;
-		cpu->a = 1;
-		cpu->f.packed = 0xB0;
-		cpu->c = 0x13;
-		cpu->e = 0xD8;
-		cpu->h = 1;
-		cpu->l = 0x4D;
+		cpu->l = 0;
+		cpu->sp = 0;
+		cpu->pc = 0;
 	}
+	if (!gb->biosVf) {
+		const struct GBCartridge* cart = (const struct GBCartridge*) &gb->memory.rom[0x100];
+		if (cart->cgb & 0x80) {
+			gb->model = GB_MODEL_CGB;
+			gb->audio.style = GB_AUDIO_CGB;
+			cpu->a = 0x11;
+			cpu->f.packed = 0x80;
+			cpu->c = 0;
+			cpu->e = 0x08;
+			cpu->h = 0;
+			cpu->l = 0x7C;
+		} else {
+			// TODO: SGB
+			gb->model = GB_MODEL_DMG;
+			gb->audio.style = GB_AUDIO_DMG;
+			cpu->a = 1;
+			cpu->f.packed = 0xB0;
+			cpu->c = 0x13;
+			cpu->e = 0xD8;
+			cpu->h = 1;
+			cpu->l = 0x4D;
+		}
+
+		cpu->sp = 0xFFFE;
+		cpu->pc = 0x100;
+	}
+
 	cpu->b = 0;
 	cpu->d = 0;
-	cpu->sp = 0xFFFE;
-	cpu->pc = 0x100;
+
 	cpu->memory.setActiveRegion(cpu, cpu->pc);
 
 	if (gb->yankedRomSize) {

@@ -62,6 +62,7 @@ size_t pristineRomSize;
 	size_t yankedRomSize;
 	uint32_t romCrc32;
 	struct VFile* romVf;
+	struct VFile* biosVf;
 	struct VFile* sramVf;
 
 	struct mAVStream* stream;
@@ -107,6 +108,8 @@ bool GBLoadROM(struct GB* gb, struct VFile* vf);
 bool GBLoadSave(struct GB* gb, struct VFile* vf);
 void GBYankROM(struct GB* gb);
 void GBUnloadROM(struct GB* gb);
+
+void GBLoadBIOS(struct GB* gb, struct VFile* vf);
 
 struct Patch;
 void GBApplyPatch(struct GB* gb, struct Patch* patch);

@@ -311,6 +311,12 @@ break;
 	case REG_STAT:
 		GBVideoWriteSTAT(&gb->video, value);
 		break;
+	case 0x50:
+		if (gb->memory.romBase != gb->memory.rom) {
+			free(gb->memory.romBase);
+			gb->memory.romBase = gb->memory.rom;
+		}
+		break;
 	case REG_IE:
 		gb->memory.ie = value;
 		GBUpdateIRQs(gb);

@@ -52,7 +52,7 @@ case GB_REGION_CART_BANK0 + 1:
 	case GB_REGION_CART_BANK0 + 2:
 	case GB_REGION_CART_BANK0 + 3:
 		cpu->memory.cpuLoad8 = GBFastLoad8;
-		cpu->memory.activeRegion = memory->rom;
+		cpu->memory.activeRegion = memory->romBase;
 		cpu->memory.activeRegionEnd = GB_BASE_CART_BANK1;
 		cpu->memory.activeMask = GB_SIZE_CART_BANK0 - 1;
 		break;
@@ -211,7 +211,7 @@ case GB_REGION_CART_BANK0:
 	case GB_REGION_CART_BANK0 + 1:
 	case GB_REGION_CART_BANK0 + 2:
 	case GB_REGION_CART_BANK0 + 3:
-		return memory->rom[address & (GB_SIZE_CART_BANK0 - 1)];
+		return memory->romBase[address & (GB_SIZE_CART_BANK0 - 1)];
 	case GB_REGION_CART_BANK1:
 	case GB_REGION_CART_BANK1 + 1:
 	case GB_REGION_CART_BANK1 + 2:

@@ -112,6 +112,7 @@
 struct mRotationSource;
 struct GBMemory {
 	uint8_t* rom;
+	uint8_t* romBase;
 	uint8_t* romBank;
 	enum GBMemoryBankControllerType mbcType;
 	GBMemoryBankController mbc;