diff --git a/src/boards/357.c b/src/boards/357.c
new file mode 100644
index 0000000..8d19ef4
--- /dev/null
+++ b/src/boards/357.c
@@ -0,0 +1,124 @@
+/* FCEUmm - NES/Famicom Emulator
+ *
+ * Copyright notice for this file:
+ *  Copyright (C) 2020 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 357 is used for a 4-in-1 multicart (cartridge ID 4602) from Bit Corp.
+ * The first game is Bit Corp's hack of the YUNG-08 conversion of Super Mario Brothers 2 (J) named Mr. Mary 2,
+ * the other three games are UNROM games.
+ *
+ * Implementation is modified so reset actually sets the correct dipswitch (or outer banks) for each of the 4 games
+ */
+
+#include "mapinc.h"
+
+static uint8 preg[4];
+static uint8 dipswitch;
+static uint32 IRQCount, IRQa;
+
+static uint8 banks[8] = { 4, 3, 5, 3, 6, 3, 7, 3 };
+static uint8 outer_bank[4] = { 0x00, 0x08, 0x10, 0x18 };
+
+static SFORMAT StateRegs[] =
+{
+	{ &IRQCount, 4 | FCEUSTATE_RLSB, "IRQC" },
+	{ &IRQa, 4 | FCEUSTATE_RLSB, "IRQA" },
+    { &dipswitch, 1, "DPSW" },
+	{ &preg, 4, "REG" },
+	{ 0 }
+};
+
+static void Sync(void) {
+    if (dipswitch == 0) {
+        /* SMB2J Mode */
+        setprg4(0x5000, 16);
+	    setprg8(0x6000, preg[1] ? 0 : 2);
+	    setprg8(0x8000, 1);
+	    setprg8(0xa000, 0);
+	    setprg8(0xc000, banks[preg[0]]);
+	    setprg8(0xe000, preg[1] ? 8 : 10);
+    } else {
+        /* UNROM Mode */
+        setprg16(0x8000, outer_bank[dipswitch] | preg[2]);
+        setprg16(0xc000, outer_bank[dipswitch] | 7);
+    }
+	setchr8(0);
+    setmirror(dipswitch == 3 ? MI_H : MI_V);
+}
+
+static DECLFW(M357WriteLo) {
+    switch (A & 0x71ff) {
+        case 0x4022: preg[0] = V & 7; Sync(); break;
+        case 0x4120: preg[1] = V & 1; Sync(); break;
+    }
+}
+
+static DECLFW(M357WriteIRQ) {
+    IRQa = V & 1;
+    if (!IRQa) {
+        IRQCount = 0;
+        X6502_IRQEnd(FCEU_IQEXT);
+    }
+}
+
+static DECLFW(M357WriteUNROM) {
+    preg[2] = V & 7;
+    Sync();
+}
+
+static void M357Power(void) {
+    preg[0] = 0;
+    preg[1] = 0;
+    IRQa = IRQCount = 0;
+	Sync();
+	SetReadHandler(0x5000, 0xffff, CartBR);
+	SetWriteHandler(0x4022, 0x4022, M357WriteLo);
+    SetWriteHandler(0x4120, 0x4120, M357WriteLo);
+    SetWriteHandler(0x4122, 0x4122, M357WriteIRQ);
+    SetWriteHandler(0x8000, 0xffff, M357WriteUNROM);
+}
+
+static void M357Reset(void) {
+    IRQa = IRQCount = 0;
+    dipswitch++;
+    dipswitch &= 3;
+    Sync();
+}
+
+static void FP_FASTAPASS(1) M357IRQHook(int a) {
+	if (IRQa) {
+		if (IRQCount < 4096)
+			IRQCount += a;
+		else {
+			IRQa = 0;
+			X6502_IRQBegin(FCEU_IQEXT);
+		}
+	}
+}
+
+static void StateRestore(int version) {
+	Sync();
+}
+
+void Mapper357_Init(CartInfo *info) {
+	info->Reset = M357Reset;
+	info->Power = M357Power;
+	MapIRQHook = M357IRQHook;
+	GameStateRestore = StateRestore;
+	AddExState(&StateRegs, ~0, 0, 0);
+}
diff --git a/src/ines.c b/src/ines.c
index 561c33c..bfcb937 100644
--- a/src/ines.c
+++ b/src/ines.c
@@ -660,6 +660,8 @@ static BMAPPINGLocal bmap[] = {
 	{(uint8_t*)"HUMMER/JY-052",			281, Mapper281_Init},
 	{(uint8_t*)"GN-45",					366, GN45_Init},
 
+	{(uint8_t*)"Bit Corp 4-in-1",		357, Mapper357_Init },
+
 	/* UNIF to NES 2.0 BOARDS */
 
 	{(uint8_t*)"OneBus",				256, UNLOneBus_Init },
diff --git a/src/ines.h b/src/ines.h
index 0121528..bcc20a6 100644
--- a/src/ines.h
+++ b/src/ines.h
@@ -243,4 +243,6 @@ void Bs5652_Init(CartInfo *);
 void NC7000M_Init(CartInfo *);
 void J2282_Init(CartInfo *);
 
+void Mapper357_Init(CartInfo *);
+
 #endif