diff --git a/src/boards/514.c b/src/boards/514.c
index fb8d823..a8b674d 100644
--- a/src/boards/514.c
+++ b/src/boards/514.c
@@ -22,7 +22,7 @@
 #include "asic_latch.h"
 #include "wram.h"
 
-uint8 chr;
+static uint8 chr;
 
 static void sync () {
 	setprg8r(0x10, 0x6000, 0);
diff --git a/src/boards/545.c b/src/boards/545.c
new file mode 100644
index 0000000..5a339e5
--- /dev/null
+++ b/src/boards/545.c
@@ -0,0 +1,70 @@
+/* FCEUmm - NES/Famicom Emulator
+ *
+ * Copyright notice for this file:
+ *  Copyright (C) 2020
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ *
+ */
+
+#include "mapinc.h"
+#include "asic_mmc3.h"
+#include "wram.h"
+
+static uint8 reg;
+
+static void sync () {
+	MMC3_syncWRAM(0);
+	MMC3_syncPRG(0x7F, 0x00);
+	MMC3_syncCHR(0x7F, reg <<7 | ~reg <<4 &0x40);
+	MMC3_syncMirror();
+}
+
+static int getPRGBank (uint8 bank) {
+	int result = MMC3_getPRGBank(bank);
+	if (reg &0x08 && ~result &0x10)
+		result =          0x40 | result &0x0F;
+	else
+		result = reg <<4 &0x30 | result &0x0F;
+	return result;
+}
+
+static DECLFW (writeReg) {
+	if (A &0x020 && A &0x100) {
+		reg = V;
+		sync();
+	} else
+		MMC3_writeReg(A, V);
+}
+
+static void reset () {
+	reg = 0;
+	MMC3_clear();
+}
+
+static void power () {
+	reg = 0;
+	MMC3_power();
+	SetWriteHandler(0xF000, 0xFFFF, writeReg);
+}
+
+void Mapper545_Init (CartInfo *info) {
+	MMC3_init(info, sync, MMC3_TYPE_AX5202P, getPRGBank, NULL, NULL, NULL);
+	WRAM_init(info, 8);
+	info->Power = power;
+	info->Reset = reset;
+	AddExState(&reg, 1, 0, "EXPR");
+}
diff --git a/src/ines.c b/src/ines.c
index 5969e5d..4fb2ea5 100644
--- a/src/ines.c
+++ b/src/ines.c
@@ -969,6 +969,7 @@ INES_BOARD_BEGIN()
 	INES_BOARD( "JYV610 830626C",           542, Mapper542_Init         )
 	INES_BOARD( "5-in-1 (CH-501)",          543, Mapper543_Init         )
 	INES_BOARD( "WAIXING FS306",            544, Mapper544_Init         )
+	INES_BOARD( "ST-80",                    545, Mapper545_Init         )
 	INES_BOARD( "Kaiser KS-7016B",          549, Mapper549_Init         )
 	INES_BOARD( "",                         550, Mapper550_Init         )
 	INES_BOARD( "",              		551, Mapper178_Init         )
diff --git a/src/ines.h b/src/ines.h
index b255d79..f6cb9d4 100644
--- a/src/ines.h
+++ b/src/ines.h
@@ -437,6 +437,7 @@ void Mapper541_Init(CartInfo *);
 void Mapper542_Init(CartInfo *);
 void Mapper543_Init(CartInfo *);
 void Mapper544_Init(CartInfo *);
+void Mapper545_Init(CartInfo *);
 void Mapper549_Init(CartInfo *);
 void Mapper550_Init(CartInfo *);
 void Mapper552_Init(CartInfo *);