diff --git a/src/boards/coolboy.c b/src/boards/coolboy.c
index 39e6f72..2e6d704 100644
--- a/src/boards/coolboy.c
+++ b/src/boards/coolboy.c
@@ -17,9 +17,14 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  *
- * CoolBoy 400-in-1 FK23C-mimic mapper 32Mb PROM + 128K CHR RAM, no wram, no CROM
+ * CoolBoy 400-in-1 FK23C-mimic mapper 16Mb/32Mb PROM + 128K/256K CHR RAM, optional SRAM, optional NTRAM
  * only MMC3 mode
  *
+ * 6000 (õõ76x210) | 0õÑ0
+ * 6001 (õõõ354õõ)
+ * 6002 = 0
+ * 6003 = 0
+ *
  */
 
 #include "mapinc.h"
@@ -28,50 +33,52 @@
 static void COOLBOYCW(uint32 A, uint8 V) {
 	if(EXPREGS[3] & 0x10)
 		setchr8(EXPREGS[2] & 0xF);
-	else
-		setchr1(A, V);
+	else {
+		uint32 mask = 0xFF;
+		switch(EXPREGS[0] & 0xC0) {
+		case 0xC0:
+			mask = 0x7F;
+			break;
+		}
+		setchr1(A, V & mask);
+	}
 }
 
 static void COOLBOYPW(uint32 A, uint8 V) {
 	uint32 mask, shift;
 	uint32 base = ((EXPREGS[0] & 0x07) >> 0) | ((EXPREGS[1] & 0x10) >> 1) | ((EXPREGS[1] & 0x0C) << 2) | ((EXPREGS[0] & 0x30) << 2);
-	switch(EXPREGS[0]&0xC0) {
+	switch(EXPREGS[0] & 0xC0) {
 	case 0x00:
-      base >>= 2;
 		mask = 0x3F;
-		shift = 6;
-      break;
-   case 0x80:
-      base >>= 1;
-      mask = 0x1F;
-      shift = 5;
+		break;
+	case 0x80:
+		mask = 0x1F;
 		break;
 	case 0xC0:
-		shift = 4;
 		if(EXPREGS[3] & 0x10) {
-         mask = 0x01 | (EXPREGS[1] & 2);
+			mask = 0x01 | (EXPREGS[1] & 2);
 		} else {
 			mask = 0x0F;
 		}
 		break;
 	}
 	if(EXPREGS[3] & 0x10)
-      setprg8(A, (base << shift) | (V & mask) | ((EXPREGS[3] & (0x0E ^ (EXPREGS[1] & 2))) ));
+		setprg8(A, (base << 4) | (V & mask) | ((EXPREGS[3] & (0x0E ^ (EXPREGS[1] & 2))) ));
 	else
-		setprg8(A, (base << shift) | (V & mask));
+		setprg8(A, (base << 4) | (V & mask));
 }
 
 static DECLFW(COOLBOYWrite) {
-	uint32_t base;
-
-	if((EXPREGS[3] & 0x80) == 0)
-   {
-		EXPREGS[A & 3] = V;
-		FixMMC3PRG(MMC3_cmd);
-		FixMMC3CHR(MMC3_cmd);
-		base = ((EXPREGS[0] & 0x07) >> 0) | ((EXPREGS[1] & 0x10) >> 1) | ((EXPREGS[1] & 0x0C) << 2) | ((EXPREGS[0] & 0x30) << 2);
-		FCEU_printf("exp %02x %02x (base %03d)\n",A,V,base);
-	}
+	if(A001B & 0x80)
+		CartBW(A,V);
+	else
+		if((EXPREGS[3] & 0x80) == 0) {
+			EXPREGS[A & 3] = V;
+			FixMMC3PRG(MMC3_cmd);
+			FixMMC3CHR(MMC3_cmd);
+			uint32 base = ((EXPREGS[0] & 0x07) >> 0) | ((EXPREGS[1] & 0x10) >> 1) | ((EXPREGS[1] & 0x0C) << 2) | ((EXPREGS[0] & 0x30) << 2);
+			FCEU_printf("exp %02x %02x (base %03d)\n",A,V,base);
+		}
 }
 
 static void COOLBOYReset(void) {
@@ -91,11 +98,10 @@ static void COOLBOYPower(void) {
 }
 
 void COOLBOY_Init(CartInfo *info) {
-	GenMMC3_Init(info, 512, 128, 0, 0);
+	GenMMC3_Init(info, 512, 128, 8, 0);
 	pwrap = COOLBOYPW;
 	cwrap = COOLBOYCW;
 	info->Power = COOLBOYPower;
 	info->Reset = COOLBOYReset;
 	AddExState(EXPREGS, 4, 0, "EXPR");
 }
-
diff --git a/src/unif.c b/src/unif.c
index 4e81292..693ae51 100644
--- a/src/unif.c
+++ b/src/unif.c
@@ -309,10 +309,11 @@ static int LoadCHR(FCEUFILE *fp) {
 	return(1);
 }
 
-#define BMCFLAG_FORCE4 1
-#define BMCFLAG_16KCHRR  2
-#define BMCFLAG_32KCHRR  4
-#define BMCFLAG_EXPCHRR  8
+#define BMCFLAG_FORCE4    0x01
+#define BMCFLAG_16KCHRR   0x02
+#define BMCFLAG_32KCHRR   0x04
+#define BMCFLAG_128KCHRR  0x08
+#define BMCFLAG_256KCHRR  0x10
 
 static BMAPPING bmap[] = {
 	{ "11160", BMC11160_Init, 0 },
@@ -352,8 +353,8 @@ static BMAPPING bmap[] = {
 	{ "ELROM", ELROM_Init, 0 },
 	{ "ETROM", ETROM_Init, 0 },
 	{ "EWROM", EWROM_Init, 0 },
-	{ "FK23C", BMCFK23C_Init, BMCFLAG_EXPCHRR },
-	{ "FK23CA", BMCFK23CA_Init, BMCFLAG_EXPCHRR },
+   { "FK23C", BMCFK23C_Init, BMCFLAG_256KCHRR },
+	{ "FK23CA", BMCFK23CA_Init, BMCFLAG_256KCHRR },
 	{ "FS304", UNLFS304_Init, 0 },
 	{ "G-146", BMCG146_Init, 0 },
 	{ "GK-192", BMCGK192_Init, 0 },
@@ -448,6 +449,7 @@ static BMAPPING bmap[] = {
 	{ "UOROM", UNROM_Init, 0 },
 	{ "VRC7", UNLVRC7_Init, 0 },
 	{ "YOKO", UNLYOKO_Init, 0 },
+   { "COOLBOY", COOLBOY_Init, BMCFLAG_256KCHRR },
 
 #ifdef COPYFAMI
 	{ "COPYFAMI_MMC3", MapperCopyFamiMMC3_Init, 0 },