diff --git a/Components/9918/9918.cpp b/Components/9918/9918.cpp
index ce23b4f19..7ea9ab00c 100644
--- a/Components/9918/9918.cpp
+++ b/Components/9918/9918.cpp
@@ -141,17 +141,20 @@ void TMS9918::run_for(const HalfCycles cycles) {
 						// Then ten access windows are filled with collection of sprite 3 and 4 details.
 						if(access_pointer_ >= 4 && access_pointer_ < 14) {
 							// TODO: this repeats the code below.
-							while(access_pointer_ < access_slot) {
-								const int target = 2 + (access_pointer_ - 4) / 6;
+							int end = std::min(14, access_slot);
+							while(access_pointer_ < end) {
+								const int offset = access_pointer_ - 2;
+								const int target = 2 + (offset / 6);
 								const int sprite = active_sprites_[target] & 31;
-								const int subcycle = access_pointer_ % 6;
+								const int subcycle = offset % 6;
+//								printf("%d: %d %d\n", access_pointer_, target, subcycle);
 								switch(subcycle) {
-									case 2: sprites_[target].y = ram_[sprite_attribute_table_address_ + (sprite << 2)];						break;
-									case 3: sprites_[target].x = ram_[sprite_attribute_table_address_ + (sprite << 2) + 1];					break;
-									case 4: sprites_[target].pattern_number = ram_[sprite_attribute_table_address_ + (sprite << 2) + 2];	break;
-									case 5: sprites_[target].colour = ram_[sprite_attribute_table_address_ + (sprite << 2) + 3];			break;
-									case 0:
-									case 1: {
+									case 0: sprites_[target].y = ram_[sprite_attribute_table_address_ + (sprite << 2)];						break;
+									case 1: sprites_[target].x = ram_[sprite_attribute_table_address_ + (sprite << 2) + 1];					break;
+									case 2: sprites_[target].pattern_number = ram_[sprite_attribute_table_address_ + (sprite << 2) + 2];	break;
+									case 3: sprites_[target].colour = ram_[sprite_attribute_table_address_ + (sprite << 2) + 3];			break;
+									case 4:
+									case 5: {
 										const int sprite_offset = sprites_[target].pattern_number & ~(sprites_16x16_ ? 3 : 0);
 										const int sprite_row = (row_ - sprites_[target].y) & 15;
 										const int sprite_address =
@@ -208,7 +211,7 @@ void TMS9918::run_for(const HalfCycles cycles) {
 											break;
 										const int sprite = slot - (slot >> 2) + 8;
 										sprite_locations_[sprite] = ram_[sprite_attribute_table_address_ + (sprite << 2)];
-									} break;	// TODO: sprites / CPU access.
+									} break;
 									case 0:
 										if(screen_mode_ != 1) {
 											colour_buffer_[character_column] = ram_[colour_base + (pattern_name_ >> 3)];
@@ -236,8 +239,8 @@ void TMS9918::run_for(const HalfCycles cycles) {
 									if(sprite_locations_[c] == 208) break;
 
 									// Skip sprite if invisible anyway.
-									int ranged_location = ((static_cast<int>(sprite_locations_[c]) + sprite_height) & 255) - sprite_height;
-									if(ranged_location > row_ || ranged_location + sprite_height < row_) continue;
+									int offset = (row_ - sprite_locations_[c])&255;
+									if(offset < 0 || offset >= sprite_height) continue;
 
 									last_visible = c;
 									if(slot < 4) {
@@ -264,10 +267,12 @@ void TMS9918::run_for(const HalfCycles cycles) {
 
 						// Fourteen access windows: collect initial sprite information.
 						if(access_pointer_ >= 156 && access_pointer_ < 170) {
-							while(access_pointer_ < access_slot) {
+							int end = std::min(170, access_slot);
+							while(access_pointer_ < end) {
 								const int target = (access_pointer_ - 156) / 6;
 								const int sprite = active_sprites_[target] & 31;
 								const int subcycle = access_pointer_ % 6;
+//								printf("%d: %d %d\n", access_pointer_, target, subcycle);
 								switch(subcycle) {
 									case 0: sprites_[target].y = ram_[sprite_attribute_table_address_ + (sprite << 2)];						break;
 									case 1: sprites_[target].x = ram_[sprite_attribute_table_address_ + (sprite << 2) + 1];					break;
@@ -286,7 +291,8 @@ void TMS9918::run_for(const HalfCycles cycles) {
 							}
 						}
 
-						// There's another unused access window here.
+						// There's a single unused access window here.
+						access_pointer_ = std::min(171, access_slot);
 					}
 				break;
 			}
@@ -368,7 +374,8 @@ void TMS9918::run_for(const HalfCycles cycles) {
 					if(output_column_ == first_right_border_column_) {
 						// Just chuck the sprites on. Quick hack!
 						for(size_t c = 0; c < 4; ++c) {
-							if(active_sprites_[c^3] == 255) continue;
+							if(active_sprites_[c^3] == 0xff) continue;
+							if(!(sprites_[c^3].colour&15)) continue;
 							for(int p = 0; p < (sprites_16x16_ ? 16 : 8); ++p) {
 								int x = sprites_[c^3].x + p;
 								if(sprites_[c^3].colour & 0x80) x -= 32;