diff --git a/Part #7 - Mappers & Basic Sounds/Mapper_004.cpp b/Part #7 - Mappers & Basic Sounds/Mapper_004.cpp
index 4c62aad..8363622 100644
--- a/Part #7 - Mappers & Basic Sounds/Mapper_004.cpp	
+++ b/Part #7 - Mappers & Basic Sounds/Mapper_004.cpp	
@@ -51,7 +51,7 @@
 
 	Author
 	~~~~~~
-	David Barr, aka javidx9, ©OneLoneCoder 2019
+	David Barr, aka javidx9, ©OneLoneCoder 2019
 */
 
 #include "Mapper_004.h"
@@ -135,46 +135,47 @@ bool Mapper_004::cpuMapWrite(uint16_t addr, uint32_t &mapped_addr, uint8_t data)
 		{
 			// Update target register
 			pRegister[nTargetRegister] = data;
+		}
 
-			// Update Pointer Table
-			if (bCHRInversion)
-			{
-				pCHRBank[0] = pRegister[2] * 0x0400;
-				pCHRBank[1] = pRegister[3] * 0x0400;
-				pCHRBank[2] = pRegister[4] * 0x0400;
-				pCHRBank[3] = pRegister[5] * 0x0400;
-				pCHRBank[4] = (pRegister[0] & 0xFE) * 0x0400;
-				pCHRBank[5] = pRegister[0] * 0x0400 + 0x0400;
-				pCHRBank[6] = (pRegister[1] & 0xFE) * 0x0400;
-				pCHRBank[7] = pRegister[1] * 0x0400 + 0x0400;
-			}
-			else
-			{
-				pCHRBank[0] = (pRegister[0] & 0xFE) * 0x0400;
-				pCHRBank[1] = pRegister[0] * 0x0400 + 0x0400;
-				pCHRBank[2] = (pRegister[1] & 0xFE) * 0x0400;
-				pCHRBank[3] = pRegister[1] * 0x0400 + 0x0400;
-				pCHRBank[4] = pRegister[2] * 0x0400;
-				pCHRBank[5] = pRegister[3] * 0x0400;
-				pCHRBank[6] = pRegister[4] * 0x0400;
-				pCHRBank[7] = pRegister[5] * 0x0400;
-			}
-
-			if (bPRGBankMode)
-			{
-				pPRGBank[2] = (pRegister[6] & 0x3F) * 0x2000;
-				pPRGBank[0] = (nPRGBanks * 2 - 2) * 0x2000;
-			}
-			else
-			{
-				pPRGBank[0] = (pRegister[6] & 0x3F) * 0x2000;
-				pPRGBank[2] = (nPRGBanks * 2 - 2) * 0x2000;
-			}
-
-			pPRGBank[1] = (pRegister[7] & 0x3F) * 0x2000;
-			pPRGBank[3] = (nPRGBanks * 2 - 1) * 0x2000;
+		// Update Pointer Table
+		if (bCHRInversion)
+		{
+			pCHRBank[0] = pRegister[2] * 0x0400;
+			pCHRBank[1] = pRegister[3] * 0x0400;
+			pCHRBank[2] = pRegister[4] * 0x0400;
+			pCHRBank[3] = pRegister[5] * 0x0400;
+			pCHRBank[4] = (pRegister[0] & 0xFE) * 0x0400;
+			pCHRBank[5] = pRegister[0] * 0x0400 + 0x0400;
+			pCHRBank[6] = (pRegister[1] & 0xFE) * 0x0400;
+			pCHRBank[7] = pRegister[1] * 0x0400 + 0x0400;
+		}
+		else
+		{
+			pCHRBank[0] = (pRegister[0] & 0xFE) * 0x0400;
+			pCHRBank[1] = pRegister[0] * 0x0400 + 0x0400;
+			pCHRBank[2] = (pRegister[1] & 0xFE) * 0x0400;
+			pCHRBank[3] = pRegister[1] * 0x0400 + 0x0400;
+			pCHRBank[4] = pRegister[2] * 0x0400;
+			pCHRBank[5] = pRegister[3] * 0x0400;
+			pCHRBank[6] = pRegister[4] * 0x0400;
+			pCHRBank[7] = pRegister[5] * 0x0400;
+		}
 
+		uint8_t lPRGBanks = (nPRGBanks * 2 - 1);
+		
+		if (bPRGBankMode)
+		{
+			pPRGBank[2] = (pRegister[6] & lPRGBanks) * 0x2000;
+			pPRGBank[0] = (nPRGBanks * 2 - 2) * 0x2000;
 		}
+		else
+		{
+			pPRGBank[0] = (pRegister[6] & lPRGBanks) * 0x2000;
+			pPRGBank[2] = (nPRGBanks * 2 - 2) * 0x2000;
+		}
+
+		pPRGBank[1] = (pRegister[7] & lPRGBanks) * 0x2000;
+		pPRGBank[3] = lPRGBanks * 0x2000;
 
 		return false;
 	}
@@ -303,7 +304,7 @@ void Mapper_004::reset()
 	nIRQReload = 0x0000;
 
 	for (int i = 0; i < 4; i++)	pPRGBank[i] = 0;
-	for (int i = 0; i < 8; i++) { pCHRBank[i] = 0; pRegister[i] = 0; }
+	for (int i = 0; i < 8; i++) { pCHRBank[i] = 0; pRegister[i] = 0xFF; }
 
 	pPRGBank[0] = 0 * 0x2000;
 	pPRGBank[1] = 1 * 0x2000;