diff --git a/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/GBC_GB_PPU.cs b/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/GBC_GB_PPU.cs
index a9c80825a1..e41ba27540 100644
--- a/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/GBC_GB_PPU.cs
+++ b/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/GBC_GB_PPU.cs
@@ -763,9 +763,6 @@ namespace BizHawk.Emulation.Cores.Nintendo.GBHawk
 			// i.e. just keeping track of the lowest x-value sprite
 			if (render_cycle == 0)
 			{
-				// window X is latched for the scanline, mid-line changes have no effect
-				window_x_latch = window_x;
-
 				OAM_scan_index = 0;
 				read_case = 0;
 				internal_cycle = 0;
@@ -1012,6 +1009,7 @@ namespace BizHawk.Emulation.Cores.Nintendo.GBHawk
 						{
 							// calculate the row number of the tiles to be fetched
 							y_tile = (((int)scroll_y + LY) >> 3) % 32;
+							x_tile = scroll_x >> 3;
 
 							temp_fetch = y_tile * 32 + (x_tile + tile_inc) % 32;
 							tile_byte = Core.VRAM[0x1800 + (LCDC.Bit(3) ? 1 : 0) * 0x400 + temp_fetch];
@@ -1103,8 +1101,10 @@ namespace BizHawk.Emulation.Cores.Nintendo.GBHawk
 								// here we set up rendering
 								pre_render = false;
 
-								// x scroll is latched here
-								x_tile = scroll_x >> 3;
+								// window X is latched for the scanline, mid-line changes have no effect
+								window_x_latch = window_x;
+
+								// x scroll is latched here, only the lower 3 bits are latched though
 								render_offset = scroll_offset = scroll_x % 8;
 
 								render_counter = 0;
diff --git a/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/GBC_PPU.cs b/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/GBC_PPU.cs
index f3cf3e619d..2886ed19ed 100644
--- a/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/GBC_PPU.cs
+++ b/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/GBC_PPU.cs
@@ -754,9 +754,6 @@ namespace BizHawk.Emulation.Cores.Nintendo.GBHawk
 			// i.e. just keeping track of the lowest x-value sprite
 			if (render_cycle == 0)
 			{
-				// window X is latched for the scanline, mid-line changes have no effect
-				window_x_latch = window_x;
-
 				OAM_scan_index = 0;
 				read_case = 0;
 				internal_cycle = 0;
@@ -966,6 +963,7 @@ namespace BizHawk.Emulation.Cores.Nintendo.GBHawk
 						{
 							// calculate the row number of the tiles to be fetched
 							y_tile = (((int)scroll_y + LY) >> 3) % 32;
+							x_tile = scroll_x >> 3;
 
 							temp_fetch = y_tile * 32 + (x_tile + tile_inc) % 32;
 							tile_byte = Core.VRAM[0x1800 + (LCDC.Bit(3) ? 1 : 0) * 0x400 + temp_fetch];
@@ -1058,8 +1056,10 @@ namespace BizHawk.Emulation.Cores.Nintendo.GBHawk
 								// here we set up rendering
 								pre_render = false;
 
-								// calculate the column number of the tile to start with
-								x_tile = scroll_x >> 3;
+								// window X is latched for the scanline, mid-line changes have no effect
+								window_x_latch = window_x;
+
+								// x scroll is latched here, only the lower 3 bits are latched though
 								render_offset = scroll_offset = scroll_x % 8;
 
 								render_counter = 0;
diff --git a/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/GB_PPU.cs b/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/GB_PPU.cs
index 701cdefde1..77a9359cfc 100644
--- a/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/GB_PPU.cs
+++ b/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/GB_PPU.cs
@@ -445,9 +445,6 @@ namespace BizHawk.Emulation.Cores.Nintendo.GBHawk
 			// i.e. just keeping track of the lowest x-value sprite
 			if (render_cycle == 0)
 			{
-				// window X is latched for the scanline, mid-line changes have no effect
-				window_x_latch = window_x;
-
 				OAM_scan_index = 0;
 				read_case = 0;
 				internal_cycle = 0;
@@ -642,6 +639,7 @@ namespace BizHawk.Emulation.Cores.Nintendo.GBHawk
 						{
 							// calculate the row number of the tiles to be fetched
 							y_tile = (((int)scroll_y + LY) >> 3) % 32;
+							x_tile = scroll_x >> 3;
 
 							temp_fetch = y_tile * 32 + (x_tile + tile_inc) % 32;
 
@@ -720,8 +718,10 @@ namespace BizHawk.Emulation.Cores.Nintendo.GBHawk
 								// here we set up rendering
 								pre_render = false;
 
+								// window X is latched for the scanline, mid-line changes have no effect
+								window_x_latch = window_x;
+
 								// x scroll is latched here
-								x_tile = scroll_x >> 3;
 								render_offset = scroll_offset = scroll_x % 8;
 
 								render_counter = 0;
diff --git a/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/Mappers/Mapper_MBC3.cs b/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/Mappers/Mapper_MBC3.cs
index 5651ff7a5f..07036610cc 100644
--- a/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/Mappers/Mapper_MBC3.cs
+++ b/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/Mappers/Mapper_MBC3.cs
@@ -1,5 +1,6 @@
 using BizHawk.Common;
 using BizHawk.Emulation.Cores.Components.LR35902;
+using System;
 
 namespace BizHawk.Emulation.Cores.Nintendo.GBHawk
 {
@@ -210,6 +211,16 @@ namespace BizHawk.Emulation.Cores.Nintendo.GBHawk
 					}
 					else if ((RAM_bank >= 8) && (RAM_bank <= 0xC))
 					{
+						// not all bits are writable
+						switch (RAM_bank - 8)
+						{
+							case 0: value &= 0x3F;		break;
+							case 1: value &= 0x3F;		break;
+							case 2: value &= 0x1F;		break;
+							case 3: value &= 0xFF;		break;
+							case 4: value &= 0xC1;		break;
+						}
+
 						RTC_regs[RAM_bank - 8] = value;
 
 						if ((RAM_bank - 8) == 0) { RTC_low_clock = RTC_timer = 0; }
@@ -256,15 +267,15 @@ namespace BizHawk.Emulation.Cores.Nintendo.GBHawk
 
 						RTC_regs[0]++;
 
-						if (RTC_regs[0] > 59)
+						if (RTC_regs[0] == 60)
 						{
 							RTC_regs[0] = 0;
 							RTC_regs[1]++;
-							if (RTC_regs[1] > 59)
+							if (RTC_regs[1] == 60)
 							{
 								RTC_regs[1] = 0;
 								RTC_regs[2]++;
-								if (RTC_regs[2] > 23)
+								if (RTC_regs[2] == 24)
 								{
 									RTC_regs[2] = 0;
 									if (RTC_regs[3] < 0xFF)
@@ -286,7 +297,19 @@ namespace BizHawk.Emulation.Cores.Nintendo.GBHawk
 										}
 									}
 								}
+								else
+								{
+									RTC_regs[2] &= 0x1F;
+								}
 							}
+							else
+							{
+								RTC_regs[1] &= 0x3F;
+							}
+						}
+						else
+						{
+							RTC_regs[0] &= 0x3F;
 						}
 					}
 				}