From 597fa4b39c2bfe1048cc4e470362db7e82bd952e Mon Sep 17 00:00:00 2001
From: TakuikaNinja <takuikaninja@gmail.com>
Date: Tue, 8 Apr 2025 16:26:58 +1200
Subject: [PATCH] FDS: Implement 4030 bit 3 read

---
 src/fds.cpp | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/fds.cpp b/src/fds.cpp
index 885728fb..c7c4a77c 100644
--- a/src/fds.cpp
+++ b/src/fds.cpp
@@ -259,7 +259,13 @@ static void FDSFix(int a) {
 
 static DECLFR(FDSRead4030) {
 	uint8 ret = 0;
-
+	
+	/* from hardware testing (#789):
+	4030(r) bit 3 = 4025(w) bit 3
+	(nametable arrangement/mirroring)
+	*/
+	ret |= (mapperFDS_control & 0x08);
+	
 	/* Cheap hack. */
 	if (X.IRQlow & FCEU_IQEXT) ret |= 1;
 	if (X.IRQlow & FCEU_IQEXT2) ret |= 2;