Add mapper 603.

src/boards/603.c

@@ -0,0 +1,33 @@
+/* FCE Ultra - NES/Famicom Emulator
+ *
+ * Copyright notice for this file:
+ *  Copyright (C) 2026 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"
+
+static void sync () {
+	setprg16(0x8000, Latch_address >>2);
+	setprg16(0xC000, Latch_address >>2);
+	setchr8(Latch_address);
+}
+
+void Mapper603_Init (CartInfo *info) {
+	Latch_init(info, sync, 0x8000, 0xFFFF, NULL);
+	info->Reset = Latch_clear;
+}

src/ines.c

@@ -1021,6 +1021,7 @@ INES_BOARD_BEGIN()
 	INES_BOARD( "GN-27",                    597, Mapper597_Init         )
 	INES_BOARD( "3936",                     598, Mapper598_Init         )
 	INES_BOARD( "ET-133A",                  599, Mapper599_Init         )
+	INES_BOARD( "J-2061",                   603, Mapper603_Init         )
 INES_BOARD_END()
 
 static uint32 iNES_get_mapper_id(void)

src/ines.h

@@ -490,6 +490,7 @@ void Mapper596_Init(CartInfo *);
 void Mapper597_Init(CartInfo *);
 void Mapper598_Init(CartInfo *);
 void Mapper599_Init(CartInfo *);
+void Mapper603_Init(CartInfo *);
 void FFE_Init(CartInfo *);
 
 #endif