From d6056bb40227a26f791de5c864a142bb55f7e6ab Mon Sep 17 00:00:00 2001
From: saxxonpike <saxxonpike@gmail.com>
Date: Sun, 18 Aug 2013 04:27:08 +0000
Subject: [PATCH] Commodore64: Fix VIC addressing for Ultimax format
 cartridges. PLA implementation should be 100% complete now

---
 .../Commodore64/C64.MotherboardInterface.cs   | 11 +---------
 .../Computers/Commodore64/MOS/MOSPLA.cs       | 21 ++++++++++++++++++-
 2 files changed, 21 insertions(+), 11 deletions(-)

diff --git a/BizHawk.Emulation/Computers/Commodore64/C64.MotherboardInterface.cs b/BizHawk.Emulation/Computers/Commodore64/C64.MotherboardInterface.cs
index a9c724fa9f..0c395f4e17 100644
--- a/BizHawk.Emulation/Computers/Commodore64/C64.MotherboardInterface.cs
+++ b/BizHawk.Emulation/Computers/Commodore64/C64.MotherboardInterface.cs
@@ -133,18 +133,9 @@ namespace BizHawk.Emulation.Computers.Commodore64
 
         byte Vic_ReadMemory(int addr)
         {
-            //p6 = a14 && !a13 && a12 && aec && game;
-            //p7 = a14 && !a13 && a12 && aec && !exrom && !game;
-            //(char rom from pla)
-
-
             // the system sees (cia1.PortAData & 0x3) but we use a shortcut
             addr |= (0x3 - (((cia1.PortALatch & cia1.PortADirection) | (~cia1.PortADirection)) & 0x3)) << 14;
-            if ((addr & 0x7000) == 0x1000)
-                bus = charRom.Read(addr);
-            else
-                bus = ram.Read(addr);
-            return bus;
+            return pla.VicRead(addr);
         }
     }
 }
diff --git a/BizHawk.Emulation/Computers/Commodore64/MOS/MOSPLA.cs b/BizHawk.Emulation/Computers/Commodore64/MOS/MOSPLA.cs
index 1f0ace85f4..e065dca408 100644
--- a/BizHawk.Emulation/Computers/Commodore64/MOS/MOSPLA.cs
+++ b/BizHawk.Emulation/Computers/Commodore64/MOS/MOSPLA.cs
@@ -387,7 +387,26 @@ namespace BizHawk.Emulation.Computers.Commodore64.MOS
 			return 0xFF;
 		}
 
-		public void Write(int addr, byte val)
+        public byte VicRead(int addr)
+        {
+            game = ReadGame();
+            exrom = ReadExRom();
+            a14 = (addr & 0x04000) == 0;
+            a13 = (addr & 0x02000) != 0;
+            a12 = (addr & 0x01000) != 0;
+
+            // read char rom at 1000-1FFF and 9000-9FFF
+            if (a14 && !a13 && a12 && (game || !exrom))
+                return ReadCharRom(addr);
+
+            // read cartridge rom in ultimax mode
+            if (a13 && a12 && exrom && !game)
+                return ReadCartridgeHi(addr);
+
+            return ReadMemory(addr);
+        }
+
+        public void Write(int addr, byte val)
 		{
 			switch (Bank(addr, false))
 			{