diff --git a/src/boards/599.c b/src/boards/599.c
new file mode 100644
index 0000000..22857d2
--- /dev/null
+++ b/src/boards/599.c
@@ -0,0 +1,80 @@
+/* FCE Ultra - NES/Famicom Emulator
+ *
+ * Copyright notice for this file:
+ *  Copyright (C) 2025 NewRisingSun
+ *
+ * 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_latch.h"
+#include "cartram.h"
+
+static uint8 pad;
+
+static DECLFR (readOB) {
+	return X.DB;
+}
+
+static void sync () {
+	/* There are two PRG-ROM chips, the first can be either 256 KiB or 512 KiB in size, the second is always 128 KiB in size */
+	int prgAND, prgOR;
+	if (ROM_size >=32) {
+		prgAND = Latch_address &0x400? 0x07: 0x1F;
+		prgOR  = Latch_address &0x400? 0x20: 0x00;
+	} else {
+		prgAND = Latch_address &0x400? 0x07: 0x0F;
+		prgOR  = Latch_address &0x400? 0x10: 0x00;
+	}
+	if (Latch_address &0x080) { /* NROM mode */
+		if (Latch_address &0x001)
+			setprg32(0x8000,(prgOR | Latch_address >>2 &prgAND) >>1);
+		else {
+			setprg16(0x8000, prgOR | Latch_address >>2 &prgAND);
+			setprg16(0xC000, prgOR | Latch_address >>2 &prgAND);
+		}
+	} else { /* Inverse UNROM mode */
+		setprg16(0x8000, prgOR | Latch_address >>2 &prgAND);
+		setprg16(0xC000, prgOR);
+	}
+	SetReadHandler(0x8000, 0xFFFF, ROM_size >=32 && Latch_address &0x200 && pad &1? readOB: CartBR);
+	if (Latch_address &0x400)
+		setchr8(Latch_address >>6 &~0x03 | Latch_data &0x03);
+	else
+		setchr8r(0x10, 0);
+	setmirror(Latch_address &0x002? MI_H: MI_V);
+}
+
+static void trapLatchWrite (uint16 *newAddress, uint8 *newValue, uint8 romValue) { /* Latch address bit 14 is an address lock bit */
+	if (Latch_address &0x4000) *newAddress = Latch_address;
+}
+
+static void power () {
+	pad = 0;
+	Latch_power();
+}
+
+static void reset () {
+	pad++;
+	Latch_clear();
+}
+
+void Mapper599_Init (CartInfo *info) {
+	Latch_init(info, sync, 0x8000, 0xFFFF, trapLatchWrite);
+	CHRRAM_init(info, 8);
+	info->Power = power;
+	info->Reset = reset;
+	AddExState(&pad, 1, 0, "DIPS");
+}
diff --git a/src/ines.c b/src/ines.c
index 1a9b070..ba47aaf 100644
--- a/src/ines.c
+++ b/src/ines.c
@@ -1020,6 +1020,7 @@ INES_BOARD_BEGIN()
 	INES_BOARD( "FC-49",                    596, Mapper596_Init         )
 	INES_BOARD( "GN-27",                    597, Mapper597_Init         )
 	INES_BOARD( "3936",                     598, Mapper598_Init         )
+	INES_BOARD( "ET-133A",                  599, Mapper599_Init         )
 INES_BOARD_END()
 
 static uint32 iNES_get_mapper_id(void)
diff --git a/src/ines.h b/src/ines.h
index b5adf55..93cd0d8 100644
--- a/src/ines.h
+++ b/src/ines.h
@@ -489,6 +489,7 @@ void Mapper595_Init(CartInfo *);
 void Mapper596_Init(CartInfo *);
 void Mapper597_Init(CartInfo *);
 void Mapper598_Init(CartInfo *);
+void Mapper599_Init(CartInfo *);
 void FFE_Init(CartInfo *);
 
 #endif