Added storage for the extended four status registers, and made an attempt at implementing the two most trivial result-phase commands. Am slightly paused momentarily trying to figure out whether seek activity is orthogonal to read/write activity.

Components/8272/i8272.cpp

@@ -13,12 +13,18 @@
 using namespace Intel;
 
 namespace {
-const uint8_t StatusRQM = 0x80;	// Set indicates: ready to send or receive from processor.
+const uint8_t StatusRQM = 0x80;	// Set: ready to send or receive from processor.
+const uint8_t StatusDIO = 0x40;	// Set: data is expected to be taken from the 8272 by the processor.
+const uint8_t StatusNDM = 0x20;	// Set: the execution phase of a data transfer command is ongoing and DMA mode is disabled.
+const uint8_t StatusD3B = 0x08;	// Set: drive 3 is seeking.
+const uint8_t StatusD2B = 0x04;	// Set: drive 2 is seeking.
+const uint8_t StatusD1B = 0x02;	// Set: drive 1 is seeking.
+const uint8_t StatusD0B = 0x01;	// Set: drive 0 is seeking.
 }
 
 i8272::i8272(Cycles clock_rate, int clock_rate_multiplier, int revolutions_per_minute) :
 	Storage::Disk::MFMController(clock_rate, clock_rate_multiplier, revolutions_per_minute),
-	status_(StatusRQM),
+	main_status_(StatusRQM),
 	interesting_event_mask_((int)Event8272::CommandByte),
 	resume_point_(0),
 	delay_time_(0) {
@@ -42,7 +48,7 @@ void i8272::set_register(int address, uint8_t value) {
 	if(!address) return;
 
 	// if not ready for commands, do nothing
-	if(!(status_ & StatusRQM)) return;
+	if(!(main_status_ & StatusRQM)) return;
 
 	// accumulate latest byte in the command byte sequence
 	command_.push_back(value);
@@ -52,10 +58,14 @@ void i8272::set_register(int address, uint8_t value) {
 uint8_t i8272::get_register(int address) {
 	if(address) {
 		printf("8272 get data\n");
-		return 0xff;
+		if(result_.empty()) return 0xff;
+		uint8_t result = result_.back();
+		result_.pop_back();
+		if(result_.empty()) posit_event((int)Event8272::ResultEmpty);
+		return result;
 	} else {
-		printf("8272 get status\n");
+		printf("8272 get main status\n");
-		return status_;
+		return main_status_;
 	}
 }
 
@@ -75,9 +85,9 @@ void i8272::posit_event(int type) {
 		command_.clear();
 
 	wait_for_complete_command_sequence:
-		status_ |= StatusRQM;
+		main_status_ |= StatusRQM;
 		WAIT_FOR_EVENT(Event8272::CommandByte)
-		status_ &= ~StatusRQM;
+		main_status_ &= ~StatusRQM;
 
 		switch(command_[0] & 0x1f) {
 			case 0x06:	// read data
@@ -144,55 +154,57 @@ void i8272::posit_event(int type) {
 		}
 
 	read_data:
-		printf("Read data unimplemented!!");
+		printf("Read data unimplemented!!\n");
 		goto wait_for_command;
 
 	read_deleted_data:
-		printf("Read deleted data unimplemented!!");
+		printf("Read deleted data unimplemented!!\n");
 		goto wait_for_command;
 
 	write_data:
-		printf("Write data unimplemented!!");
+		printf("Write data unimplemented!!\n");
 		goto wait_for_command;
 
 	write_deleted_data:
-		printf("Write deleted data unimplemented!!");
+		printf("Write deleted data unimplemented!!\n");
 		goto wait_for_command;
 
 	read_track:
-		printf("Read track unimplemented!!");
+		printf("Read track unimplemented!!\n");
 		goto wait_for_command;
 
 	read_id:
-		printf("Read ID unimplemented!!");
+		printf("Read ID unimplemented!!\n");
 		goto wait_for_command;
 
 	format_track:
-		printf("Fromat track unimplemented!!");
+		printf("Fromat track unimplemented!!\n");
 		goto wait_for_command;
 
 	scan_low:
-		printf("Scan low unimplemented!!");
+		printf("Scan low unimplemented!!\n");
 		goto wait_for_command;
 
 	scan_low_or_equal:
-		printf("Scan low or equal unimplemented!!");
+		printf("Scan low or equal unimplemented!!\n");
 		goto wait_for_command;
 
 	scan_high_or_equal:
-		printf("Scan high or equal unimplemented!!");
+		printf("Scan high or equal unimplemented!!\n");
 		goto wait_for_command;
 
 	recalibrate:
-		printf("Recalibrate unimplemented!!");
+		printf("Recalibrate unimplemented!!\n");
 		goto wait_for_command;
 
 	sense_interrupt_status:
-		printf("Sense interrupt status unimplemented!!");
+		printf("Sense interrupt status\n");
-		goto wait_for_command;
+		result_.push_back(head_position_);
+		result_.push_back(status_[0]);
+		goto post_result;
 
 	specify:
-		printf("Specify");
+		printf("Specify\n");
 		step_rate_time_ = command_[1] &0xf0;		// i.e. 16 to 240m
 		head_unload_time_ = command_[1] & 0x0f;		// i.e. 1 to 16ms
 		head_load_time_ = command_[2] & ~1;			// i.e. 2 to 254 ms in increments of 2ms
@@ -200,16 +212,23 @@ void i8272::posit_event(int type) {
 		goto wait_for_command;
 
 	sense_drive_status:
-		printf("Sense drive status unimplemented!!");
+		printf("Sense drive status\n");
-		goto wait_for_command;
+		result_.push_back(status_[3]);
+		goto post_result;
 
 	seek:
-		printf("Seek unimplemented!!");
+		printf("Seek unimplemented!!\n");
 		goto wait_for_command;
 
 	invalid:
 		// A no-op, causing the FDC to go back into standby mode.
 		goto wait_for_command;
 
+	post_result:
+		main_status_ |= StatusRQM | StatusDIO;
+		WAIT_FOR_EVENT(Event8272::ResultEmpty);
+		main_status_ &= ~StatusDIO;
+		goto wait_for_command;
+
 	END_SECTION()
 }

Components/8272/i8272.hpp

@@ -27,13 +27,16 @@ class i8272: public Storage::Disk::MFMController {
 
 	private:
 		void posit_event(int type);
-		uint8_t status_;
+		uint8_t main_status_;
+		uint8_t status_[4];
+
 		std::vector<uint8_t> command_;
+		std::vector<uint8_t> result_;
 
 		enum class Event8272: int {
 			CommandByte	= (1 << 3),
 			Timer = (1 << 4),
-
+			ResultEmpty = (1 << 5),
 		};
 
 		int interesting_event_mask_;
@@ -44,6 +47,8 @@ class i8272: public Storage::Disk::MFMController {
 		int head_unload_time_;
 		int head_load_time_;
 		bool dma_mode_;
+
+		uint8_t head_position_;
 };
 
 }