Add mapper 542.

src/boards/529.c

@@ -55,7 +55,7 @@ void UNLT230_Init (CartInfo *info) {
 	VRC24_init(info, sync, 0x04, 0x08, 1, 1, 0);
 	if (info->PRGRamSaveSize) {
 		info->Power =UNLT230_power;
-		AddExState(stateRegs, ~0, 0, 0);	
+		AddExState(stateRegs, ~0, 0, 0);
 		eeprom_93Cx6_storage = eeprom_data;
 		info->battery = 1;
 		info->SaveGame[0] = eeprom_data;

src/boards/542.c

@@ -0,0 +1,60 @@
+/* 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 "vrc2and4.h"
+
+static uint8 reg;
+
+static SFORMAT stateRegs[] ={
+        { &reg, 1, "EXP0" },
+        { 0 }
+};
+
+static void sync () {
+	setprg8(0x6000, 0x0F);
+	VRC24_syncPRG(0x01F, 0x000);
+	VRC24_syncCHR(0x1FF, 0x000);
+	VRC24_syncMirror();
+	if (reg &1) setchr1r(0x10, 0x0C00, 1);
+}
+
+DECLFW(Mapper542_writeExtra) {
+	if (A &0x800) {
+		reg =A >>12;
+		VRC24_Sync();
+	} else
+		VRC24_writeReg(A, V);
+}
+
+
+void Mapper542_power (void) {
+	reg =0;
+	VRC24_power();
+	SetReadHandler(0x6000, 0x7FFF, CartBR);
+	SetWriteHandler(0xD000, 0xEFFF, Mapper542_writeExtra);
+}
+
+void Mapper542_Init (CartInfo *info) {
+	VRC24_init(info, sync, 0x01, 0x02, 1, 1, 0);
+	info->Power =Mapper542_power;
+	AddExState(stateRegs, ~0, 0, 0);
+	SetupCartCHRMapping(0x10, NTARAM, 0x200, 1);
+}

src/ines.c

@@ -885,6 +885,7 @@ INES_BOARD_BEGIN()
 	INES_BOARD( "Kid Ikarus (FDS)",         539, Mapper539_Init         )
 	INES_BOARD( "82112C",                   540, Mapper540_Init         )
 	INES_BOARD( "LittleCom 160-in-1",       541, Mapper541_Init         )
+	INES_BOARD( "JYV610 830626C",           542, Mapper542_Init         )
 	INES_BOARD( "5-in-1 (CH-501)",          543, Mapper543_Init         )
 	INES_BOARD( "",              		551, Mapper178_Init         )
 	INES_BOARD( "SACHEN 3013",              553, Mapper553_Init         )

src/ines.h

@@ -384,6 +384,7 @@ void Mapper538_Init(CartInfo *);
 void Mapper539_Init(CartInfo *);
 void Mapper540_Init(CartInfo *);
 void Mapper541_Init(CartInfo *);
+void Mapper542_Init(CartInfo *);
 void Mapper543_Init(CartInfo *);
 void Mapper550_Init(CartInfo *);
 void Mapper553_Init(CartInfo *);