Gets explicit about DHIRES being annunciator 3; implements four-colour high res mode.

Machines/AppleII/AppleII.cpp

@@ -534,7 +534,7 @@ template <Analyser::Static::AppleII::Target::Model model> class ConcreteMachine:
 #undef IIeSwitchRead
 
 								case 0xc07f:
-									if(is_iie()) *value = (*value & 0x7f) | (video_->get_double_high_resolution() ? 0x80 : 0x00);
+									if(is_iie()) *value = (*value & 0x7f) | (video_->get_annunciator_3() ? 0x80 : 0x00);
 								break;
 							}
 						} else {
@@ -611,7 +611,7 @@ template <Analyser::Static::AppleII::Target::Model model> class ConcreteMachine:
 						analogue_charge_ = 0.0f;
 					} break;
 
-					/* Read-write switches. */
+					/* Switches triggered by reading or writing. */
 					case 0xc050:
 					case 0xc051:
 						update_video();
@@ -636,7 +636,7 @@ template <Analyser::Static::AppleII::Target::Model model> class ConcreteMachine:
 					case 0xc05f:
 						if(is_iie()) {
 							update_video();
-							video_->set_double_high_resolution(!(address&1));
+							video_->set_annunciator_3(!(address&1));
 						}
 					break;
 

Machines/AppleII/Video.cpp

@@ -131,15 +131,16 @@ bool VideoBase::get_high_resolution() {
 	return set_high_resolution_;
 }
 
-void VideoBase::set_double_high_resolution(bool double_high_resolution) {
+void VideoBase::set_annunciator_3(bool annunciator_3) {
-	set_double_high_resolution_ = double_high_resolution;
+	set_annunciator_3_ = annunciator_3;
 	deferrer_.defer(Cycles(2), [=] {
-		double_high_resolution_ = double_high_resolution;
+		annunciator_3_ = annunciator_3;
+		high_resolution_mask_ = annunciator_3_ ? 0x7f : 0xff;
 	});
 }
 
-bool VideoBase::get_double_high_resolution() {
+bool VideoBase::get_annunciator_3() {
-	return set_double_high_resolution_;
+	return set_annunciator_3_;
 }
 
 void VideoBase::set_character_rom(const std::vector<uint8_t> &character_rom) {
@@ -276,7 +277,9 @@ void VideoBase::output_high_resolution(uint8_t *target, const uint8_t *const sou
 	for(size_t c = 0; c < length; ++c) {
 		// High resolution graphics shift out LSB to MSB, optionally with a delay of half a pixel.
 		// If there is a delay, the previous output level is held to bridge the gap.
-		if(source[c] & 0x80) {
+		// Delays may be ignored on a IIe if Annunciator 3 is set; that's the state that
+		// high_resolution_mask_ models.
+		if(source[c] & high_resolution_mask_ & 0x80) {
 			target[0] = graphics_carry_;
 			target[1] = target[2] = source[c] & 0x01;
 			target[3] = target[4] = source[c] & 0x02;

Machines/AppleII/Video.hpp

@@ -128,18 +128,19 @@ class VideoBase {
 		bool get_high_resolution();
 
 		/*!
-			Setter for DHIRES ($C05E/$C05F; triggers on write only).
+			Setter for annunciator 3.
 
-			* On: turn on double-high resolution.
+			* On: turn on annunciator 3.
-			* Off: turn off double-high resolution.
+			* Off: turn off annunciator 3.
 
-			DHIRES doesn't exist on a II/II+. On the IIe there is another
+			This exists on both the II/II+ and the IIe, but has no effect on
-			register usually grouped with the graphics setters called IOUDIS
+			video on the older machines. It's intended to be used on the IIe
-			that affects visibility of this switch. But it has no effect on
+			to confirm double-high resolution mode but has side effects in
-			video, so it's not modelled by this class.
+			selecting mixed mode output and discarding high-resolution
+			delay bits.
 		*/
-		void set_double_high_resolution(bool);
+		void set_annunciator_3(bool);
-		bool get_double_high_resolution();
+		bool get_annunciator_3();
 
 		// Setup for text mode.
 		void set_character_rom(const std::vector<uint8_t> &);
@@ -176,13 +177,14 @@ class VideoBase {
 		bool text_ = true, set_text_ = true;
 		bool mixed_ = false, set_mixed_ = false;
 		bool high_resolution_ = false, set_high_resolution_ = false;
-		bool double_high_resolution_ = false, set_double_high_resolution_ = false;
+		bool annunciator_3_ = false, set_annunciator_3_ = false;
 
 		// Graphics carry is the final level output in a fetch window;
 		// it carries on into the next if it's high resolution with
 		// the delay bit set.
 		mutable uint8_t graphics_carry_ = 0;
 		bool was_double_ = false;
+		uint8_t high_resolution_mask_ = 0xff;
 
 		// This holds a copy of the character ROM. The regular character
 		// set is assumed to be in the first 64*8 bytes; the alternative
@@ -539,14 +541,14 @@ template <class BusHandler, bool is_iie> class Video: public VideoBase {
 		}
 
 		GraphicsMode graphics_mode(int row) {
-			if(text_) return columns_80_ ? GraphicsMode::DoubleText : GraphicsMode::Text;
+			if(
-			if(mixed_ && row >= 160 && row < 192) {
+				text_ ||
-				return (columns_80_ || double_high_resolution_) ? GraphicsMode::DoubleText : GraphicsMode::Text;
+				(mixed_ && row >= 160 && row < 192)
-			}
+			) return columns_80_ ? GraphicsMode::DoubleText : GraphicsMode::Text;
 			if(high_resolution_) {
-				return double_high_resolution_ ? GraphicsMode::DoubleHighRes : GraphicsMode::HighRes;
+				return (annunciator_3_ && columns_80_) ? GraphicsMode::DoubleHighRes : GraphicsMode::HighRes;
 			} else {
-				return double_high_resolution_ ? GraphicsMode::DoubleLowRes : GraphicsMode::LowRes;
+				return annunciator_3_ ? GraphicsMode::DoubleLowRes : GraphicsMode::LowRes;
 			}
 		}