diff --git a/src/boards/528.c b/src/boards/528.c
new file mode 100644
index 0000000..e9e6dc1
--- /dev/null
+++ b/src/boards/528.c
@@ -0,0 +1,127 @@
+/* FCEUmm - NES/Famicom Emulator
+ *
+ * Copyright notice for this file:
+ *  Copyright (C) 2023
+ *
+ * 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 528 
+ * UNIF BMC-831128C
+ */
+
+#include "mapinc.h"
+#include "vrcirq.h"
+
+static uint8 preg[4], creg[8], mirr;
+static uint8 gamesel;
+static uint8 *WRAM;
+static uint32 WRAMSIZE;
+
+static SFORMAT StateRegs[] =
+{
+	{ preg, 4, "PREG" },
+	{ creg, 8, "CREG" },
+	{ &mirr, 1, "MIRR" },
+    { &gamesel, 1, "GSEL" },
+	{ 0 }
+};
+
+static void Sync(void) {
+    uint8 mask = (gamesel << 4) | 0x0F;
+	if (preg[3] == 1) {
+		setprg8r(0x10, 0x6000, 0);
+    } else {
+		setprg8(0x6000, (preg[3] & mask) + gamesel);
+    }
+	setprg8(0x8000, (preg[0] & mask) + (gamesel << 4));
+	setprg8(0xA000, (preg[1] & mask) + (gamesel << 4));
+	setprg8(0xC000, (     ~1 & mask) + (gamesel << 4));
+	setprg8(0xE000, (     ~0 & mask) + (gamesel << 4));
+	setchr1(0x0000, creg[0] + (gamesel << 8));
+    setchr1(0x0400, creg[1] + (gamesel << 8));
+    setchr1(0x0800, creg[2] + (gamesel << 8));
+    setchr1(0x0C00, creg[3] + (gamesel << 8));
+    setchr1(0x1000, creg[4] + (gamesel << 8));
+    setchr1(0x1400, creg[5] + (gamesel << 8));
+    setchr1(0x1800, creg[6] + (gamesel << 8));
+    setchr1(0x1C00, creg[7] + (gamesel << 8));
+	switch (mirr & 3) {
+		case 0: setmirror(MI_V); break;
+		case 1: setmirror(MI_H); break;
+		case 2: setmirror(MI_0); break;
+		case 3: setmirror(MI_1); break;
+	}
+}
+
+static DECLFW(M528Write1) {
+	switch (A & 0x0F) {
+	case 0x0: creg[0] = V; break;
+	case 0x1: creg[1] = V; break;
+	case 0x2: creg[2] = V; break;
+	case 0x3: creg[3] = V; break;
+	case 0x4: creg[4] = V; break;
+	case 0x5: creg[5] = V; break;
+	case 0x6: creg[6] = V; break;
+	case 0x7: creg[7] = V; break;
+	case 0x8: preg[3] = V; break;
+	case 0x9: preg[0] = V; break;
+	case 0xA: preg[1] = V; break;
+	case 0xB: break;
+	case 0xC: mirr = V & 3; break;
+	case 0xD: VRCIRQ_Control(V); break;
+	case 0xE: VRCIRQ_Acknowledge(); break;
+	case 0xF: VRCIRQ_Latch(V); break;
+	}
+	gamesel = (A & 0x4000) >> 14;
+    Sync();
+}
+
+static void M528Power(void) {
+    int i;
+    gamesel = 0;
+    preg[0] = 0;
+    preg[1] = 1;
+    preg[2] = 0;
+    preg[3] = 0;
+    for (i = 0; i < 8; i++) {
+        creg[i] = i;
+    }
+	Sync();
+
+	SetReadHandler(0x8000, 0xFFFF, CartBR);
+	SetWriteHandler(0xA000, 0xAFFF, M528Write1);
+    SetWriteHandler(0xC000, 0xCFFF, M528Write1);
+
+    SetReadHandler(0x6000, 0x7FFF, CartBR);
+    SetWriteHandler(0x6000, 0x7FFF, CartBW);
+    FCEU_CheatAddRAM(WRAMSIZE >> 10, 0x6000, WRAM);
+}
+
+static void StateRestore(int version) {
+	Sync();
+}
+
+void Mapper528_Init(CartInfo *info) {
+	info->Power = M528Power;
+	GameStateRestore = StateRestore;
+    VRCIRQ_Init();
+    AddExState(&StateRegs, ~0, 0, 0);
+
+    WRAMSIZE = 8192;
+    WRAM = (uint8*) FCEU_gmalloc(WRAMSIZE);
+    SetupCartPRGMapping(0x10, WRAM, WRAMSIZE, 1);
+    AddExState(WRAM, WRAMSIZE, 0, "WRAM");
+}
diff --git a/src/boards/vrcirq.c b/src/boards/vrcirq.c
new file mode 100644
index 0000000..d12d3d3
--- /dev/null
+++ b/src/boards/vrcirq.c
@@ -0,0 +1,93 @@
+#include "mapinc.h"
+#include "vrcirq.h"
+
+static int16 IRQPrescaler;
+static uint8 IRQCount;
+static uint8 IRQLatch;
+static uint8 IRQd;
+static uint8 IRQa;
+static uint8 IRQm;
+
+static SFORMAT StateRegs[] =
+{
+	{ &IRQPrescaler,  2, "PREC" },
+	{ &IRQCount,      1, "IRQC" },
+	{ &IRQLatch,      1, "IRQL" },
+	{ &IRQd,          1, "IRQD" },
+	{ &IRQa,          1, "IRQA" },
+	{ &IRQm,          1, "IRQM" },
+
+	{ 0 }
+};
+
+static void FP_FASTAPASS(1) VRCIRQ_IrqHook(int a)
+{
+	int count = a;
+
+	if (!IRQa) {
+		return;
+	}
+
+	while (count) {
+		count--;
+		IRQPrescaler -= 3;
+		if (IRQm || (IRQPrescaler < 0 && !IRQm)) {
+			IRQPrescaler += 341;
+			if (IRQCount == 0xFF) {
+				X6502_IRQBegin(FCEU_IQEXT);
+				IRQCount = IRQLatch;
+			} else {
+				IRQCount++;
+			}
+		}
+	}
+}
+
+void VRCIRQ_Init(void)
+{
+	IRQPrescaler  = 0;
+	IRQCount      = 0;
+	IRQLatch      = 0;
+	IRQd          = 0;
+	IRQa          = 0;
+	IRQm          = 0;
+	MapIRQHook    = VRCIRQ_IrqHook;
+
+	AddExState(&StateRegs, ~0, 0, 0);
+}
+
+void VRCIRQ_Latch(uint8 V)
+{
+	IRQLatch = V;
+}
+
+void VRCIRQ_LatchNibble(uint8 V, uint8 highBit)
+{
+	if (highBit) {
+		IRQLatch &= 0x0F;
+		IRQLatch |= V << 4;
+	} else {
+		IRQLatch &= 0xF0;
+		IRQLatch |= V & 0xF;
+	}
+}
+
+void VRCIRQ_Control(uint8 V)
+{
+	IRQd = (V & 0x01) == 0x01;
+	IRQa = (V & 0x02) == 0x02;
+	IRQm = (V & 0x04) == 0x04;
+	IRQPrescaler = 341;
+
+	if (IRQa) {
+		IRQCount = IRQLatch;
+	}
+
+	X6502_IRQEnd(FCEU_IQEXT);
+}
+
+void VRCIRQ_Acknowledge(void)
+{
+	IRQa = IRQd;
+	X6502_IRQEnd(FCEU_IQEXT);
+}
diff --git a/src/boards/vrcirq.h b/src/boards/vrcirq.h
new file mode 100644
index 0000000..5a98137
--- /dev/null
+++ b/src/boards/vrcirq.h
@@ -0,0 +1,10 @@
+#ifndef _VRCIRQ_H
+#define _VRCIRQ_H
+
+void VRCIRQ_Init(void);
+void VRCIRQ_Latch(uint8 V);
+void VRCIRQ_LatchNibble(uint8 V, uint8 highBit);
+void VRCIRQ_Control(uint8 V);
+void VRCIRQ_Acknowledge(void);
+
+#endif /* _VRCIRQ_H */
\ No newline at end of file
diff --git a/src/ines.c b/src/ines.c
index 2cd9219..345d4c8 100644
--- a/src/ines.c
+++ b/src/ines.c
@@ -848,6 +848,7 @@ INES_BOARD_BEGIN()
 	INES_BOARD( "KS7021A",                  525, UNLKS7021A_Init        )
 	INES_BOARD( "BJ-56",                    526, UNLBJ56_Init           )
 	INES_BOARD( "AX-40G",                   527, UNLAX40G_Init          )
+	INES_BOARD( "831128C",                  528, Mapper528_Init         )
 	INES_BOARD( "T-230",                    529, UNLT230_Init           )
 	INES_BOARD( "AX5705",                   530, UNLAX5705_Init         )
 	INES_BOARD( "Sachen 3014",              533, Mapper533_Init         )
diff --git a/src/ines.h b/src/ines.h
index 7901730..0d4f5f4 100644
--- a/src/ines.h
+++ b/src/ines.h
@@ -348,6 +348,7 @@ void Mapper501_Init(CartInfo *);
 void Mapper502_Init(CartInfo *);
 void Mapper516_Init(CartInfo *);
 void Mapper523_Init(CartInfo *);
+void Mapper528_Init(CartInfo *);
 void Mapper533_Init(CartInfo *);
 void Mapper534_Init(CartInfo *);
 void Mapper538_Init(CartInfo *);
diff --git a/src/unif.c b/src/unif.c
index d2d964f..a022ec8 100644
--- a/src/unif.c
+++ b/src/unif.c
@@ -446,6 +446,7 @@ static BMAPPING bmap[] = {
 	{ "AX5705",                     530, UNLAX5705_Init,        0 },
 	{ "BB",                         108, UNLBB_Init,            0 },
 	{ "BS-110",                     444, Mapper444_Init,        0 }, /* Due to a mix-up, UNIF MAPR BMC-BS-110 is actually the NC7000M PCB and refers to NES 2.0 Mapper 444 instead. */
+	{ "831128C",                    528, Mapper528_Init,        0 },
 	{ "BS-5",                       286, BMCBS5_Init,           0 },
 	{ "CC-21",                       27, UNLCC21_Init,          0 },
 	{ "CITYFIGHT",                  266, UNLCITYFIGHT_Init,     0 },