diff --git a/src/boards/267.c b/src/boards/267.c
index 1b53e89..2780fd0 100644
--- a/src/boards/267.c
+++ b/src/boards/267.c
@@ -34,9 +34,11 @@ static void M267PW(uint32 A, uint8 V) {
 }
 
 static DECLFW(M267Write) {
-	EXPREGS[0] = V;
-	FixMMC3PRG(MMC3_cmd);
-	FixMMC3CHR(MMC3_cmd);
+	if (!(EXPREGS[0] & 0x80)) {
+		EXPREGS[0] = V;
+		FixMMC3PRG(MMC3_cmd);
+		FixMMC3CHR(MMC3_cmd);
+	}
 }
 
 static void M267Reset(void) {
@@ -47,14 +49,14 @@ static void M267Reset(void) {
 static void M267Power(void) {
 	EXPREGS[0] = 0;
 	GenMMC3Power();
-	SetWriteHandler(0x6000, 0x6FFF, M267Write);
+	SetWriteHandler(0x6000, 0x7FFF, M267Write);
 }
 
 void Mapper267_Init(CartInfo *info) {
-	GenMMC3_Init(info, 128, 128, 0, 0);
+	GenMMC3_Init(info, 256, 128, 0, 0);
 	cwrap = M267CW;
 	pwrap = M267PW;
 	info->Reset = M267Reset;
 	info->Power = M267Power;
-	AddExState(EXPREGS, 4, 0, "EXPR");
+	AddExState(EXPREGS, 1, 0, "EXPR");
 }
diff --git a/src/boards/377.c b/src/boards/377.c
new file mode 100644
index 0000000..bece1b2
--- /dev/null
+++ b/src/boards/377.c
@@ -0,0 +1,64 @@
+/* FCEUmm - NES/Famicom Emulator
+ *
+ * Copyright notice for this file:
+ * Copyright (C) 2022 negativeExponent
+ *
+ * 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.
+ */
+
+/* NES 2.0 Mapper 377 - NES 2.0 Mapper 377 is used for the
+ * 1998 Super Game 8-in-1 (JY-111) pirate multicart. It works similarly to Mapper 267 except it has an outer 256KiB PRG-ROM bank.
+ */
+
+#include "mapinc.h"
+#include "mmc3.h"
+
+#define OUTER_BANK (((EXPREGS[0] & 0x20) >> 2) | (EXPREGS[0] & 0x06))
+
+static void M377CW(uint32 A, uint8 V) {
+	setchr1(A, (V & 0x7F) | (OUTER_BANK << 6));
+}
+
+static void M377PW(uint32 A, uint8 V) {
+	setprg8(A, (V & 0x0F) | (OUTER_BANK << 3));
+}
+
+static DECLFW(M377Write) {
+    if (!(EXPREGS[0] & 0x80)) {
+		EXPREGS[0] = V;
+		FixMMC3PRG(MMC3_cmd);
+		FixMMC3CHR(MMC3_cmd);
+	}
+}
+
+static void M377Reset(void) {
+	EXPREGS[0] = 0;
+	MMC3RegReset();
+}
+
+static void M377Power(void) {
+	EXPREGS[0] = 0;
+	GenMMC3Power();
+	SetWriteHandler(0x6000, 0x7FFF, M377Write);
+}
+
+void Mapper377_Init(CartInfo *info) {
+	GenMMC3_Init(info, 128, 128, 0, 0);
+	cwrap = M377CW;
+	pwrap = M377PW;
+	info->Reset = M377Reset;
+	info->Power = M377Power;
+	AddExState(EXPREGS, 1, 0, "EXPR");
+}
diff --git a/src/ines.c b/src/ines.c
index 4d89bab..76d090f 100644
--- a/src/ines.c
+++ b/src/ines.c
@@ -788,6 +788,7 @@ INES_BOARD_BEGIN()
 	INES_BOARD( "3D-BLOCK",                 355, UNL3DBlock_Init        )
 	INES_BOARD( "YY860606C",                358, Mapper358_Init         )
 	INES_BOARD( "N49C-300",                 369, Mapper369_Init         )
+	INES_BOARD( "JY-111/JY-112",            377, Mapper377_Init         )
 	INES_BOARD( "YY860729C",                386, Mapper386_Init         )
 	INES_BOARD( "YY850735C",                387, Mapper387_Init         )
 	INES_BOARD( "YY850835C",                388, Mapper388_Init         )
diff --git a/src/ines.h b/src/ines.h
index 5874029..57c87e9 100644
--- a/src/ines.h
+++ b/src/ines.h
@@ -273,6 +273,7 @@ void Mapper370_Init(CartInfo *);
 void Mapper372_Init(CartInfo *);
 void Mapper374_Init(CartInfo *);
 void Mapper376_Init(CartInfo *);
+void Mapper377_Init(CartInfo *);
 void Mapper380_Init(CartInfo *);
 void Mapper381_Init(CartInfo *);
 void Mapper382_Init(CartInfo *);