From e47f935b2e7726bb37394eb85ffcd071c4012211 Mon Sep 17 00:00:00 2001
From: nsx0r <nnssxx@gmail.com>
Date: Sat, 15 Apr 2023 11:42:35 +0200
Subject: [PATCH] [NES] Fixed mapper 3 CHR bus conflict

Fixed mapper 3 CHR bus conflict
---
 Cart_Reader/NES.ino | 26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/Cart_Reader/NES.ino b/Cart_Reader/NES.ino
index 514c136..706b373 100644
--- a/Cart_Reader/NES.ino
+++ b/Cart_Reader/NES.ino
@@ -3735,13 +3735,15 @@ void readCHR(boolean readrom) {
           }
           break;
 
-        case 3:   // 8K/16K/32K
-        case 66:  // 16K/32K
-        case 70:
-        case 152:  // 128K
+        case 3:   // 8K/16K/32K - bus conflicts
           banks = int_pow(2, chrsize) / 2;
-          for (int i = 0; i < banks; i++) {  // 8K Banks
-            write_prg_byte(0x8000, i);       // CHR Bank 0
+          for (int i = 0; i < banks; i++) {
+            for (int x = 0; x < 0x2000; x++) {
+              if (read_prg_byte(0x8000 + x) == i) {
+                write_prg_byte(0x8000 + x, i);
+                break;
+              }
+            }
             for (word address = 0x0; address < 0x2000; address += 512) {
               dumpCHR(address);
             }
@@ -4159,6 +4161,18 @@ void readCHR(boolean readrom) {
             }
           }
           break;
+          
+        case 66:  // 16K/32K
+        case 70:
+        case 152:  // 128K
+          banks = int_pow(2, chrsize) / 2;
+          for (int i = 0; i < banks; i++) {  // 8K Banks
+            write_prg_byte(0x8000, i);       // CHR Bank 0
+            for (word address = 0x0; address < 0x2000; address += 512) {
+              dumpCHR(address);
+            }
+          }
+          break;
 
         case 67:  // 128K
           banks = int_pow(2, chrsize) * 2;