It would help if i checked in the file

BizHawk.Emulation/Consoles/Nintendo/NES/Boards/JALECO_JF_07.cs

@@ -0,0 +1,68 @@
+using System;
+using System.IO;
+using System.Diagnostics;
+
+
+namespace BizHawk.Emulation.Consoles.Nintendo
+{
+	/*
+	PRG-ROM - 32kb
+	CHR-ROM - 16kb
+	Mirroring - Vertical
+	ines Mapper 87 (Board JALECO_JF_05 is also classified under mapper 87)
+	
+	Example Games:
+	--------------------------
+	Argus (J)
+	*/
+	class JALECO_JF_07: NES.NESBoardBase
+	{
+		bool hibit, lowbit;
+
+		public override bool Configure(NES.EDetectionOrigin origin)
+		{
+			switch (Cart.board_type)
+			{
+				case "JALECO-JF-07":
+					break;
+				default:
+					return false;
+			}
+			SetMirrorType(NES.NESBoardBase.EMirrorType.Vertical);
+			return true;
+		}
+
+		public override void SyncState(Serializer ser)
+		{
+			base.SyncState(ser);
+			ser.Sync("hibit", ref hibit);
+			ser.Sync("lowbit", ref lowbit);
+		}
+
+		public override void WriteWRAM(int addr, byte value)
+		{
+			hibit = value.Bit(0);
+			lowbit = value.Bit(1);
+		}
+
+		public override byte ReadPPU(int addr)
+		{
+			if (addr < 0x2000)
+			{
+				if (lowbit)
+				{
+					if (hibit)
+						return VROM[addr + 0x6000];
+					return VROM[addr + 0x2000];
+				}
+				else
+				{
+					if (hibit)
+						return VROM[addr + 0x4000];
+					return VROM[addr];
+				}
+			}
+			return base.ReadPPU(addr);
+		}
+	}
+}