diff --git a/Makefile.rules b/Makefile.rules
index d4679f5..1fe4669 100644
--- a/Makefile.rules
+++ b/Makefile.rules
@@ -13,7 +13,7 @@ LD	= $(PREFIX)ld
 AR	= $(PREFIX)ar
 
 ifeq ($(strip $(RASPPI)),0)
-ARCH	?= -march=armv6zk -mtune=arm1176jzf-s -mfpu=vfp -mfloat-abi=hard -DRPIZERO=1
+ARCH	?= -march=armv6zk -mtune=arm1176jzf-s -mfpu=vfp -mfloat-abi=hard -DRPIZERO=1 -DEXPERIMENTALZERO=1
 CFLAGS	+= -DRPIZERO=1 -DRASPPI=1
 else ifeq ($(strip $(RASPPI)),1)
 ARCH	?= -march=armv6zk -mtune=arm1176jzf-s -mfpu=vfp -mfloat-abi=hard -DRPIBPLUS=1
diff --git a/src/DiskCaddy.cpp b/src/DiskCaddy.cpp
index cd8bbcc..2cc9781 100644
--- a/src/DiskCaddy.cpp
+++ b/src/DiskCaddy.cpp
@@ -44,6 +44,7 @@ bool DiskCaddy::Empty()
 		if (disks[index].IsDirty())
 		{
 			anyDirty = true;
+#if not defined(EXPERIMENTALZERO)
 			if (screen)
 			{
 				x = screen->ScaleX(screenPosXCaddySelections);
@@ -52,7 +53,7 @@ bool DiskCaddy::Empty()
 				snprintf(buffer, 256, "Saving %s\r\n", disks[index].GetName());
 				screen->PrintText(false, x, y, buffer, RGBA(0xff, 0xff, 0xff, 0xff), red);
 			}
-
+#endif
 			if (screenLCD)
 			{
 				RGBA BkColour = RGBA(0, 0, 0, 0xFF);
@@ -73,6 +74,7 @@ bool DiskCaddy::Empty()
 
 	if (anyDirty)
 	{
+#if not defined(EXPERIMENTALZERO)
 		if (screen)
 		{
 			x = screen->ScaleX(screenPosXCaddySelections);
@@ -81,7 +83,7 @@ bool DiskCaddy::Empty()
 			snprintf(buffer, 256, "Saving Complete             \r\n");
 			screen->PrintText(false, x, y, buffer, RGBA(0xff, 0xff, 0xff, 0xff), red);
 		}
-
+#endif
 		if (screenLCD)
 		{
 			RGBA BkColour = RGBA(0, 0, 0, 0xFF);
@@ -112,6 +114,7 @@ bool DiskCaddy::Insert(const FILINFO* fileInfo, bool readOnly)
 	FRESULT res = f_open(&fp, fileInfo->fname, FA_READ);
 	if (res == FR_OK)
 	{
+#if not defined(EXPERIMENTALZERO)
 		if (screen)
 		{
 			x = screen->ScaleX(screenPosXCaddySelections);
@@ -120,6 +123,7 @@ bool DiskCaddy::Insert(const FILINFO* fileInfo, bool readOnly)
 			snprintf(buffer, 256, "Loading %s\r\n", fileInfo->fname);
 			screen->PrintText(false, x, y, buffer, RGBA(0xff, 0xff, 0xff, 0xff), red);
 		}
+#endif
 
 		if (screenLCD)
 		{
@@ -135,7 +139,6 @@ bool DiskCaddy::Insert(const FILINFO* fileInfo, bool readOnly)
 			screenLCD->PrintText(false, x, y, buffer, RGBA(0xff, 0xff, 0xff, 0xff), red);
 			screenLCD->SwapBuffers();
 		}
-
 		u32 bytesRead;
 		SetACTLed(true);
 		f_read(&fp, DiskImage::readBuffer, READBUFFER_SIZE, &bytesRead);
@@ -254,6 +257,7 @@ void DiskCaddy::Display()
 	unsigned caddyIndex;
 	int x;
 	int y;
+#if not defined(EXPERIMENTALZERO)
 	if (screen)
 	{
 		x = screen->ScaleX(screenPosXCaddySelections);
@@ -281,6 +285,7 @@ void DiskCaddy::Display()
 	//	RGBA BkColour = RGBA(0, 0, 0, 0xFF);
 	//	screenLCD->Clear(BkColour);
 	//}
+#endif
 	ShowSelectedImage(0);
 }
 
@@ -288,6 +293,7 @@ void DiskCaddy::ShowSelectedImage(u32 index)
 {
 	u32 x;
 	u32 y;
+#if not defined(EXPERIMENTALZERO)
 	if (screen)
 	{
 		x = screen->ScaleX(screenPosXCaddySelections) - 16;
@@ -295,6 +301,8 @@ void DiskCaddy::ShowSelectedImage(u32 index)
 		snprintf(buffer, 256, "*");
 		screen->PrintText(false, x, y, buffer, white, red);
 	}
+#endif
+
 	if (screenLCD)
 	{
 		unsigned numberOfImages = GetNumberOfImages();
@@ -352,21 +360,23 @@ bool DiskCaddy::Update()
 	u32 caddyIndex = GetSelectedIndex();
 	if (caddyIndex != oldCaddyIndex)
 	{
+#if not defined(EXPERIMENTALZERO)
 		if (screen)
 		{
 			x = screen->ScaleX(screenPosXCaddySelections) - 16;
 			y = screen->ScaleY(screenPosYCaddySelections) + 16 + 16 * oldCaddyIndex;
 			snprintf(buffer, 256, " ");
 			screen->PrintText(false, x, y, buffer, red, red);
-			oldCaddyIndex = caddyIndex;
-			ShowSelectedImage(oldCaddyIndex);
 		}
+#endif
+
+		oldCaddyIndex = caddyIndex;
+		ShowSelectedImage(oldCaddyIndex);
 
 		if (screenLCD)
 		{
 			
 		}
-
 		return true;
 	}
 	return false;
diff --git a/src/DiskCaddy.h b/src/DiskCaddy.h
index e8d881f..b59247b 100644
--- a/src/DiskCaddy.h
+++ b/src/DiskCaddy.h
@@ -28,12 +28,19 @@ class DiskCaddy
 public:
 	DiskCaddy()
 		: selectedIndex(0)
+#if not defined(EXPERIMENTALZERO)
 		, screen(0)
+#endif
 		, screenLCD(0)
 	{
 	}
-
-	void SetScreen(Screen* screen, ScreenBase* screenLCD) { this->screen = screen; this->screenLCD = screenLCD; }
+	void SetScreen(Screen* screen, ScreenBase* screenLCD) 
+	{ 
+#if not defined(EXPERIMENTALZERO)
+		this->screen = screen;
+#endif
+		this->screenLCD = screenLCD; 
+	}
 
 	bool Empty();
 
@@ -41,6 +48,9 @@ public:
 
 	DiskImage* GetCurrentDisk()
 	{
+#if defined(EXPERIMENTALZERO)
+		Update();
+#endif
 		if (selectedIndex < disks.size())
 			return &disks[selectedIndex];
 
@@ -50,14 +60,17 @@ public:
 	DiskImage* NextDisk()
 	{
 		selectedIndex = (selectedIndex + 1) % (u32)disks.size();
+		auto ret = GetCurrentDisk();
 		return GetCurrentDisk();
 	}
 
 	DiskImage* PrevDisk()
 	{
-		--selectedIndex;
-		if ((int)selectedIndex < 0)
-			selectedIndex += (u32)disks.size();
+		if (selectedIndex == 0u)
+			selectedIndex += (u32)disks.size()-1;
+		else
+			--selectedIndex;
+
 		return GetCurrentDisk();
 	}
 
@@ -99,8 +112,9 @@ private:
 	std::vector<DiskImage> disks;
 	u32 selectedIndex;
 	u32 oldCaddyIndex;
-
+#if not defined(EXPERIMENTALZERO)
 	ScreenBase* screen;
+#endif
 	ScreenBase* screenLCD;
 };
 
diff --git a/src/DiskImage.cpp b/src/DiskImage.cpp
index 10cbc63..e9ba652 100644
--- a/src/DiskImage.cpp
+++ b/src/DiskImage.cpp
@@ -151,7 +151,12 @@ void DiskImage::Close()
 
 void DiskImage::DumpTrack(unsigned track)
 {
+
+#if defined(EXPERIMENTALZERO)
+	unsigned char* src = &tracks[track << 13];
+#else
 	unsigned char* src = tracks[track];
+#endif
 	unsigned trackLength = trackLengths[track];
 	DEBUG_LOG("track = %d trackLength = %d\r\n", track, trackLength);
 	for (unsigned index = 0; index < trackLength; ++index)
@@ -205,7 +210,11 @@ bool DiskImage::OpenD64(const FILINFO* fileInfo, unsigned char* diskImage, unsig
 	for (unsigned halfTrackIndex = 0; halfTrackIndex < last_track * 2; ++halfTrackIndex)
 	{
 		unsigned char track = (halfTrackIndex >> 1);
+#if defined(EXPERIMENTALZERO)
+		unsigned char* dest = &tracks[halfTrackIndex << 13];
+#else
 		unsigned char* dest = tracks[halfTrackIndex];
+#endif
 
 		trackLengths[halfTrackIndex] = SectorsPerTrack[track] * GCR_SECTOR_LENGTH;
 
@@ -800,7 +809,11 @@ bool DiskImage::OpenG64(const FILINFO* fileInfo, unsigned char* diskImage, unsig
 				//DEBUG_LOG("trackLength = %d offset = %d\r\n", trackLength, offset);
 				trackData += 2;
 				trackLengths[track] = trackLength;
+#if defined(EXPERIMENTALZERO)
+				memcpy(&tracks[track << 13], trackData, trackLength);
+#else
 				memcpy(tracks[track], trackData, trackLength);
+#endif
 				trackUsed[track] = true;
 				//DEBUG_LOG("%d has data\r\n", track);
 			}
@@ -899,7 +912,11 @@ bool DiskImage::WriteG64(char* name)
 
 			gcr_track[0] = (BYTE)(track_len % 256);
 			gcr_track[1] = (BYTE)(track_len / 256);
+#if defined(EXPERIMENTALZERO)
+			memcpy(buffer, &tracks[track << 13], track_len);
+#else
 			memcpy(buffer, tracks[track], track_len);
+#endif
 
 			memcpy(gcr_track + 2, buffer, track_len);
 			bytesToWrite = G64_TRACK_MAXLEN + 2;
@@ -965,11 +982,19 @@ bool DiskImage::OpenNIB(const FILINFO* fileInfo, unsigned char* diskImage, unsig
 
 			unsigned char* nibdata = diskImage + (t_index * NIB_TRACK_LENGTH) + 0x100;
 			int align;
+#if defined(EXPERIMENTALZERO)
+			trackLengths[track] = extract_GCR_track(&tracks[track << 13], nibdata, &align
+				//, ALIGN_GAP
+				, ALIGN_NONE
+				, capacity_min[trackDensity[track]],
+				capacity_max[trackDensity[track]]);
+#else
 			trackLengths[track] = extract_GCR_track(tracks[track], nibdata, &align
 				//, ALIGN_GAP
 				, ALIGN_NONE
 				, capacity_min[trackDensity[track]],
 				capacity_max[trackDensity[track]]);
+#endif
 
 			trackUsed[track] = true;
 
@@ -1031,7 +1056,11 @@ bool DiskImage::WriteNIB()
 			{
 				if (trackUsed[track])
 				{
+#if defined(EXPERIMENTALZERO)
+					if (f_write(&fp, &tracks[track << 13], bytesToWrite, &bytesWritten) != FR_OK || bytesToWrite != bytesWritten)
+#else
 					if (f_write(&fp, tracks[track], bytesToWrite, &bytesWritten) != FR_OK || bytesToWrite != bytesWritten)
+#endif
 					{
 						DEBUG_LOG("Cannot write track data.\r\n");
 					}
@@ -1250,10 +1279,18 @@ void DiskImage::DecodeBlock(unsigned track, int bitIndex, unsigned char* buf, in
 	unsigned char gcr[5];
 	unsigned char byte;
 	unsigned char* offset;
+#if defined(EXPERIMENTALZERO)
+	unsigned char* end = &tracks[track << 13] + trackLengths[track];
+#else
 	unsigned char* end = tracks[track] + trackLengths[track];
+#endif
 
 	shift = bitIndex & 7;
+#if defined(EXPERIMENTALZERO)
+	offset = &tracks[track << 13] + (bitIndex >> 3);
+#else
 	offset = tracks[track] + (bitIndex >> 3);
+#endif
 
 	byte = offset[0] << shift;
 	for (i = 0; i < num; i++, buf += 4)
@@ -1262,7 +1299,11 @@ void DiskImage::DecodeBlock(unsigned track, int bitIndex, unsigned char* buf, in
 		{
 			offset++;
 			if (offset >= end)
+#if defined(EXPERIMENTALZERO)
+				offset = &tracks[track << 13];
+#else
 				offset = tracks[track];
+#endif
 		
 			if (shift)
 			{
@@ -1282,7 +1323,11 @@ void DiskImage::DecodeBlock(unsigned track, int bitIndex, unsigned char* buf, in
 int DiskImage::FindSync(unsigned track, int bitIndex, int maxBits, int* syncStartIndex)
 {
 	int readShiftRegister = 0;
+#if defined(EXPERIMENTALZERO)
+	unsigned char byte = tracks[(track << 13) + (bitIndex >> 3)] << (bitIndex & 7);
+#else
 	unsigned char byte = tracks[track][bitIndex >> 3] << (bitIndex & 7);
+#endif
 	bool prevBitZero = true;
 
 	while (maxBits--)
@@ -1314,7 +1359,11 @@ int DiskImage::FindSync(unsigned track, int bitIndex, int maxBits, int* syncStar
 			bitIndex++;
 			if (bitIndex >= MAX_TRACK_LENGTH * 8)
 				bitIndex = 0;
+#if defined(EXPERIMENTALZERO)
+			byte = tracks[(track << 13)+(bitIndex >> 3)];
+#else
 			byte = tracks[track][bitIndex >> 3];
+#endif
 		}
 	}
 	return -1;
diff --git a/src/DiskImage.h b/src/DiskImage.h
index 42a2a7a..5dc3adf 100644
--- a/src/DiskImage.h
+++ b/src/DiskImage.h
@@ -78,19 +78,48 @@ public:
 
 	bool GetDecodedSector(u32 track, u32 sector, u8* buffer);
 
+	inline unsigned char GetNextByte(u32 track, u32 byte)
+	{
+#if defined(EXPERIMENTALZERO)
+		return tracks[(track << 13) + byte];
+#else
+		return tracks[track][byte];
+#endif
+	}
+
+
 	inline bool GetNextBit(u32 track, u32 byte, u32 bit)
 	{
 		//if (attachedImageSize == 0)
 		//	return 0;
 
+#if defined(EXPERIMENTALZERO)
+		return ((tracks[(track << 13) + byte] >> bit) & 1) != 0;
+#else
 		return ((tracks[track][byte] >> bit) & 1) != 0;
+#endif
 	}
 
+
 	inline void SetBit(u32 track, u32 byte, u32 bit, bool value)
 	{
 		if (attachedImageSize == 0)
 			return;
 
+#if defined(EXPERIMENTALZERO)
+		u8 dataOld = tracks[(track << 13) + byte];
+		u8 bitMask = 1 << bit;
+		if (value)
+		{
+			TestDirty(track, (dataOld & bitMask) == 0);
+			tracks[(track << 13) + byte] |= bitMask;
+		}
+		else
+		{
+			TestDirty(track, (dataOld & bitMask) != 0);
+			tracks[(track << 13) + byte] &= bitMask;
+		}
+#else
 		u8 dataOld = tracks[track][byte];
 		u8 bitMask = 1 << bit;
 		if (value)
@@ -103,6 +132,7 @@ public:
 			TestDirty(track, (dataOld & bitMask) != 0);
 			tracks[track][byte] &= ~bitMask;
 		}
+#endif
 	}
 
 	static const unsigned char SectorsPerTrack[42];
@@ -160,7 +190,11 @@ public:
 
 	union
 	{
+#if defined(EXPERIMENTALZERO)
+		unsigned char tracks[HALF_TRACK_COUNT * MAX_TRACK_LENGTH];
+#else
 		unsigned char tracks[HALF_TRACK_COUNT][MAX_TRACK_LENGTH];
+#endif
 		unsigned char tracksD81[HALF_TRACK_COUNT][2][MAX_TRACK_LENGTH];
 	};
 
diff --git a/src/Drive.cpp b/src/Drive.cpp
index f05b519..e121e49 100644
--- a/src/Drive.cpp
+++ b/src/Drive.cpp
@@ -346,12 +346,20 @@ extern "C"
 
 Drive::Drive() : m_pVIA(0)
 {
-	Reset();
 	srand(0x811c9dc5U);
+#if defined(EXPERIMENTALZERO)
+	localSeed = 0x811c9dc5U;
+#endif
+	Reset();
 }
 
 void Drive::Reset()
 {
+#if defined(EXPERIMENTALZERO)
+	LED = false;
+	cyclesForBit = 0;
+	UE7Counter = 16;
+#endif
 	headTrackPos = 18*2;		// Start with the head over track 19 (Very later Vorpal ie Cakifornia Games) need to have had the last head movement -ve
 	CLOCK_SEL_AB = 3;		// Track 18 will use speed zone 3 (encoder/decoder (ie UE7Counter) clocked at 1.2307Mhz)
 	UpdateHeadSectorPosition();
@@ -361,7 +369,12 @@ void Drive::Reset()
 	readShiftRegister = 0;
 	writeShiftRegister = 0;
 	UE3Counter = 0;
+#if defined(EXPERIMENTALZERO)
+	ResetEncoderDecoder(18 * 16, 4 * 16);
+	cyclesLeftForBit = ceil(cyclesPerBit - cyclesForBit);
+#else
 	ResetEncoderDecoder(18.0f, 22.0f);
+#endif
 	newDiskImageQueuedCylesRemaining = DISK_SWAP_CYCLES_DISK_EJECTING + DISK_SWAP_CYCLES_NO_DISK + DISK_SWAP_CYCLES_DISK_INSERTING;
 	m_pVIA->InputCA1(true);	// Reset in read mode
 	m_pVIA->InputCB1(true);
@@ -456,6 +469,29 @@ bool Drive::Update()
 		// UE6 provides the CPU's clock by dividing the 16Mhz clock by 16.
 		// UE7 (a 74ls193 4bit counter) counts up on the falling edge of the 16Mhz clock. UE7 drives the Encoder/Decoder clock.
 		// So we need to simulate 16 cycles for every 1 CPU cycle
+#if defined(EXPERIMENTALZERO)
+		if (writing)
+			DriveLoopWrite();
+		else
+		{
+			if (fluxReversalCyclesLeft > 16 && cyclesLeftForBit > 16)
+			{
+				DriveLoopReadNoFluxNoCycles();
+			}
+			else if (fluxReversalCyclesLeft > 16)
+			{
+				DriveLoopReadNoFlux();
+			}
+			else if (cyclesLeftForBit > 16)
+			{
+				DriveLoopReadNoCycles();
+			}
+			else
+			{
+				DriveLoopRead();
+			}
+		}
+#else
 		for (int cycles = 0; cycles < 16; ++cycles)
 		{
 			if (!writing)
@@ -534,6 +570,7 @@ bool Drive::Update()
 				}
 			}
 		}
+#endif
 	}
 	m_pVIA->InputCA1(!SO);
 
@@ -544,3 +581,285 @@ bool Drive::Update()
 
 	return dataReady;
 }
+
+
+#if defined(EXPERIMENTALZERO)
+#define min(a,b) (((a) < (b)) ? (a) : (b))
+#define max(a,b) (((a) > (b)) ? (a) : (b))
+
+void Drive::DriveLoopReadNoFluxNoCycles()
+{
+	unsigned int cycles = 16;
+	fluxReversalCyclesLeft -= 16;
+	cyclesLeftForBit -= 16;
+	while (true)
+	{
+		if (cycles < UE7Counter)
+		{
+			UE7Counter -= cycles;
+			cycles = 0;
+			return;
+		}
+		cycles -= UE7Counter;
+
+		UE7Counter = 16 - CLOCK_SEL_AB;	// A and B inputs of UE7 come from the VIA's CLOCK SEL A/B outputs (ie PB5/6) ie preload the encoder/decoder clock for the current density settings.
+									// The decoder consists of UF4 and UE5A. The ecoder has two outputs, Pin 1 of UE5A is the serial data output and pin 2 of UF4 (output B) is the serial clock output.
+		++UF4Counter &= 0xf; // Clock and clamp UF4.
+								// The UD2 read shift register is clocked by serial clock (the rising edge of encoder/decoder's UF4 B output (serial clock))
+								//	- ie on counts 2, 6, 10 and 14 (2 is the only count that outputs a 1 into readShiftRegister as the MSB bits of the count NORed together for other values are 0)
+		if ((UF4Counter & 0x3) == 2)
+		{
+			readShiftRegister <<= 1;
+			readShiftRegister |= (UF4Counter == 2); 
+
+			//writeShiftRegister <<= 1;
+			
+			bool resetTime = ((readShiftRegister & 0x3ff) == 0x3ff);
+			m_pVIA->GetPortB()->SetInput(0x80, !resetTime);
+			if (resetTime)	// if the last 10 bits are 1s then SYNC
+				UE3Counter = 0;	// Phase lock on to byte boundary
+			else
+				UE3Counter++;
+		}
+		// UC5B (NOR used to invert UF4's output B serial clock) output high when UF4 counts 0,1,4,5,8,9,12 and 13
+		else if (((UF4Counter & 2) == 0) && (UE3Counter == 8))	// Phase locked on to byte boundary
+		{
+			UE3Counter = 0;
+			SO = (m_pVIA->GetFCR() & m6522::FCR_CA2_OUTPUT_MODE0) != 0;	// bit 2 of the FCR indicates "Byte Ready Active" turned on or not.
+//			writeShiftRegister = readShiftRegister;
+			m_pVIA->GetPortA()->SetInput(readShiftRegister & 0xff);
+		}
+	};
+}
+
+void Drive::DriveLoopReadNoFlux()
+{
+	unsigned int minCycles;
+	unsigned int cycles = 16;
+
+	fluxReversalCyclesLeft -= 16;
+
+	while (true)
+	{
+		minCycles = min(min(cyclesLeftForBit, cycles), UE7Counter);
+		cyclesLeftForBit -= minCycles;
+		cycles -= minCycles;
+		UE7Counter -= minCycles;
+
+		if (cycles == 0)
+			return;
+
+		if (cyclesLeftForBit == 0)
+		{
+			cyclesForBitErrorCounter -= cyclesPerBitErrorConstant;
+			cyclesLeftForBit = cyclesPerBitInt + (cyclesForBitErrorCounter < cyclesPerBitErrorConstant);
+
+			//cyclesForBit -= cyclesPerBit;
+			//cyclesLeftForBit = ceil(cyclesPerBit - cyclesForBit);
+			//cyclesForBit += cyclesLeftForBit;
+
+			if (GetNextBit())
+			{
+				ResetEncoderDecoder(18 * 16, /*20 * 16*/ 2 * 16);
+			}
+			if (cycles < UE7Counter)
+			{
+				UE7Counter -= cycles;
+				cyclesLeftForBit -= cycles;
+				return;
+			}
+			cyclesLeftForBit -= UE7Counter;
+			cycles -= UE7Counter;
+		}
+
+		//if (UE7Counter == 0x0) // The count carry (bit 4) clocks UF4.
+		{
+			UE7Counter = 16 - CLOCK_SEL_AB;	// A and B inputs of UE7 come from the VIA's CLOCK SEL A/B outputs (ie PB5/6) ie preload the encoder/decoder clock for the current density settings.
+										// The decoder consists of UF4 and UE5A. The ecoder has two outputs, Pin 1 of UE5A is the serial data output and pin 2 of UF4 (output B) is the serial clock output.
+			++UF4Counter &= 0xf; // Clock and clamp UF4.
+								 // The UD2 read shift register is clocked by serial clock (the rising edge of encoder/decoder's UF4 B output (serial clock))
+								 //	- ie on counts 2, 6, 10 and 14 (2 is the only count that outputs a 1 into readShiftRegister as the MSB bits of the count NORed together for other values are 0)
+			if ((UF4Counter & 0x3) == 2)
+			{
+				readShiftRegister <<= 1;
+				readShiftRegister |= (UF4Counter == 2);
+
+				//writeShiftRegister <<= 1;
+
+				bool resetTime = ((readShiftRegister & 0x3ff) == 0x3ff);
+				m_pVIA->GetPortB()->SetInput(0x80, !resetTime);
+				if (resetTime)	// if the last 10 bits are 1s then SYNC
+					UE3Counter = 0;	// Phase lock on to byte boundary
+				else
+					UE3Counter++;
+			}
+			// UC5B (NOR used to invert UF4's output B serial clock) output high when UF4 counts 0,1,4,5,8,9,12 and 13
+			else if (((UF4Counter & 2) == 0) && (UE3Counter == 8))	// Phase locked on to byte boundary
+			{
+				UE3Counter = 0;
+				SO = (m_pVIA->GetFCR() & m6522::FCR_CA2_OUTPUT_MODE0) != 0;	// bit 2 of the FCR indicates "Byte Ready Active" turned on or not.
+	//			writeShiftRegister = readShiftRegister;
+				m_pVIA->GetPortA()->SetInput(readShiftRegister & 0xff);
+			}
+		}
+	};
+}
+void Drive::DriveLoopReadNoCycles()
+{
+	unsigned int minCycles;
+	unsigned int cycles = 16;
+
+	cyclesLeftForBit -= 16;
+	while (true)
+	{
+		minCycles = min(cycles, min(UE7Counter, fluxReversalCyclesLeft));
+		fluxReversalCyclesLeft -= minCycles;
+		cycles -= minCycles;
+		UE7Counter -= minCycles;
+
+		if (cycles == 0)
+			return;
+
+		if (fluxReversalCyclesLeft == 0)//Not entirely right, a flux reversal will be skipped if a bit read was going to happen
+		{
+			ResetEncoderDecoder(2 * 16, /*25 * 16*/23 * 16); // Trigger a random noise generated zero crossing and start seeing more anywhere between 2us and 25us after this one.
+		}
+
+		if (UE7Counter == 0x0) // The count carry (bit 4) clocks UF4.
+		{
+			UE7Counter = 16 - CLOCK_SEL_AB;	// A and B inputs of UE7 come from the VIA's CLOCK SEL A/B outputs (ie PB5/6) ie preload the encoder/decoder clock for the current density settings.
+										// The decoder consists of UF4 and UE5A. The ecoder has two outputs, Pin 1 of UE5A is the serial data output and pin 2 of UF4 (output B) is the serial clock output.
+			++UF4Counter &= 0xf; // Clock and clamp UF4.
+								 // The UD2 read shift register is clocked by serial clock (the rising edge of encoder/decoder's UF4 B output (serial clock))
+								 //	- ie on counts 2, 6, 10 and 14 (2 is the only count that outputs a 1 into readShiftRegister as the MSB bits of the count NORed together for other values are 0)
+			if ((UF4Counter & 0x3) == 2)
+			{
+				readShiftRegister <<= 1;
+				readShiftRegister |= (UF4Counter == 2);
+
+				//writeShiftRegister <<= 1;
+
+				bool resetTime = ((readShiftRegister & 0x3ff) == 0x3ff);
+				m_pVIA->GetPortB()->SetInput(0x80, !resetTime);
+				if (resetTime)	// if the last 10 bits are 1s then SYNC
+					UE3Counter = 0;	// Phase lock on to byte boundary
+				else
+					UE3Counter++;
+			}
+			// UC5B (NOR used to invert UF4's output B serial clock) output high when UF4 counts 0,1,4,5,8,9,12 and 13
+			else if (((UF4Counter & 2) == 0) && (UE3Counter == 8))	// Phase locked on to byte boundary
+			{
+				UE3Counter = 0;
+				SO = (m_pVIA->GetFCR() & m6522::FCR_CA2_OUTPUT_MODE0) != 0;	// bit 2 of the FCR indicates "Byte Ready Active" turned on or not.
+	//			writeShiftRegister = readShiftRegister;
+				m_pVIA->GetPortA()->SetInput(readShiftRegister & 0xff);
+			}
+		}
+	};
+}
+
+void Drive::DriveLoopRead()
+{
+	unsigned int minCycles;
+	unsigned int cycles = 16;
+
+	while (true)
+	{
+		minCycles = min(min(cyclesLeftForBit, cycles), min(UE7Counter, fluxReversalCyclesLeft));
+		cyclesLeftForBit -= minCycles;
+		fluxReversalCyclesLeft -= minCycles;
+		cycles -= minCycles;
+		UE7Counter -= minCycles;
+
+		if (cycles == 0)
+			return;
+
+		if (cyclesLeftForBit == 0)
+		{
+			cyclesForBitErrorCounter -= cyclesPerBitErrorConstant;
+			cyclesLeftForBit = cyclesPerBitInt + (cyclesForBitErrorCounter < cyclesPerBitErrorConstant);
+
+			if (GetNextBit())
+			{
+				ResetEncoderDecoder(18 * 16, /*20 * 16*/ 2 * 16);
+			}
+		}
+
+		if (fluxReversalCyclesLeft == 0)//Not entirely right, a flux reversal will be skipped if a bit read was going to happen
+		{
+			ResetEncoderDecoder(2 * 16, /*25 * 16*/23 * 16); // Trigger a random noise generated zero crossing and start seeing more anywhere between 2us and 25us after this one.
+		}
+
+		if (UE7Counter == 0x0) // The count carry (bit 4) clocks UF4.
+		{
+			UE7Counter = 16-CLOCK_SEL_AB;	// A and B inputs of UE7 come from the VIA's CLOCK SEL A/B outputs (ie PB5/6) ie preload the encoder/decoder clock for the current density settings.
+										// The decoder consists of UF4 and UE5A. The ecoder has two outputs, Pin 1 of UE5A is the serial data output and pin 2 of UF4 (output B) is the serial clock output.
+			++UF4Counter &= 0xf; // Clock and clamp UF4.
+								 // The UD2 read shift register is clocked by serial clock (the rising edge of encoder/decoder's UF4 B output (serial clock))
+								 //	- ie on counts 2, 6, 10 and 14 (2 is the only count that outputs a 1 into readShiftRegister as the MSB bits of the count NORed together for other values are 0)
+			if ((UF4Counter & 0x3) == 2)
+			{
+				readShiftRegister <<= 1;
+				readShiftRegister |= (UF4Counter == 2);
+
+				//writeShiftRegister <<= 1;
+
+				bool resetTime = ((readShiftRegister & 0x3ff) == 0x3ff);
+				m_pVIA->GetPortB()->SetInput(0x80, !resetTime);
+				if (resetTime)	// if the last 10 bits are 1s then SYNC
+					UE3Counter = 0;	// Phase lock on to byte boundary
+				else
+					UE3Counter++;
+			}
+			// UC5B (NOR used to invert UF4's output B serial clock) output high when UF4 counts 0,1,4,5,8,9,12 and 13
+			else if (((UF4Counter & 2) == 0) && (UE3Counter == 8))	// Phase locked on to byte boundary
+			{
+				UE3Counter = 0;
+				SO = (m_pVIA->GetFCR() & m6522::FCR_CA2_OUTPUT_MODE0) != 0;	// bit 2 of the FCR indicates "Byte Ready Active" turned on or not.
+	//			writeShiftRegister = readShiftRegister;
+				m_pVIA->GetPortA()->SetInput(readShiftRegister & 0xff);
+			}
+		}
+	};
+}
+
+void Drive::DriveLoopWrite()
+{
+	unsigned int cycles = 16;
+	while(true)
+	{
+		if (cycles < UE7Counter)
+		{
+			UE7Counter -= cycles;
+			cycles = 0;
+			return;
+		}
+		
+		cycles -= UE7Counter;
+
+		UE7Counter = 16 - CLOCK_SEL_AB;	// A and B inputs of UE7 come from the VIA's CLOCK SEL A/B outputs (ie PB5/6) ie preload the encoder/decoder clock for the current density settings.
+									// The decoder consists of UF4 and UE5A. The ecoder has two outputs, Pin 1 of UE5A is the serial data output and pin 2 of UF4 (output B) is the serial clock output.
+		++UF4Counter &= 0xf; // Clock and clamp UF4.
+								// The UD2 read shift register is clocked by serial clock (the rising edge of encoder/decoder's UF4 B output (serial clock))
+								//	- ie on counts 2, 6, 10 and 14 (2 is the only count that outputs a 1 into readShiftRegister as the MSB bits of the count NORed together for other values are 0)
+		if ((UF4Counter & 0x3) == 2)
+		{
+			readShiftRegister <<= 1;
+			readShiftRegister |= (UF4Counter == 2); // Emulate UE5A and only shift in a 1 when pins 6 (output C) and 7 (output D) (bits 2 and 3 of UF4Counter are 0. ie the first count of the bit cell)
+
+			SetNextBit((writeShiftRegister & 0x80));
+
+			writeShiftRegister <<= 1;
+			// Note: SYNC can only trigger during reading as R/!W line is one of UC2's inputs.
+			UE3Counter++;
+		}
+		// UC5B (NOR used to invert UF4's output B serial clock) output high when UF4 counts 0,1,4,5,8,9,12 and 13
+		else if (((UF4Counter & 2) == 0) && (UE3Counter == 8))	// Phase locked on to byte boundary
+		{
+			UE3Counter = 0;
+			SO = (m_pVIA->GetFCR() & m6522::FCR_CA2_OUTPUT_MODE0) != 0;	// bit 2 of the FCR indicates "Byte Ready Active" turned on or not.
+			writeShiftRegister = m_pVIA->GetPortA()->GetOutput();
+		}
+	}
+}
+#endif
\ No newline at end of file
diff --git a/src/Drive.h b/src/Drive.h
index 1640358..00646f5 100644
--- a/src/Drive.h
+++ b/src/Drive.h
@@ -23,6 +23,17 @@
 #include "DiskImage.h"
 #include <stdlib.h>
 
+#if defined(EXPERIMENTALZERO)
+inline int ceil(float num) {
+	int inum = (int)num;
+	if (num == (float)inum) {
+		return inum;
+	}
+	return inum + 1;
+}
+#endif
+
+
 class Drive
 {
 public:
@@ -37,6 +48,14 @@ public:
 	static void OnPortOut(void*, unsigned char status);
 
 	bool Update();
+#if defined(EXPERIMENTALZERO)
+	void DriveLoopWrite();
+	void DriveLoopRead();
+	void DriveLoopReadNoFluxNoCycles();
+	void DriveLoopReadNoFlux();
+	void DriveLoopReadNoCycles();
+#endif
+
 	void Insert(DiskImage* diskImage);
 	inline const DiskImage* GetDiskImage() const { return diskImage; }
 	void Eject();
@@ -49,6 +68,16 @@ public:
 
 	inline unsigned char GetLastHeadDirection() const { return lastHeadDirection; } // For simulated head movement sounds
 private:
+#if defined(EXPERIMENTALZERO)
+	int32_t localSeed;
+	inline void ResetEncoderDecoder(unsigned int min, unsigned int /*max*/span)
+	{
+		UE7Counter = 16 - CLOCK_SEL_AB;	// A and B inputs of UE7 come from the VIA's CLOCK SEL A/B outputs (ie PB5/6)
+		UF4Counter = 0;
+		localSeed = ((localSeed * 1103515245) + 12345) & 0x7fffffff;
+		fluxReversalCyclesLeft = (span) * (localSeed >> 11) + min;
+	}
+#else
 	inline float GenerateRandomFluxReversalTime(float min, float max) { return ((max - min) * ((float)rand() / RAND_MAX)) + min; } // Inputs in micro seconds
 
 	inline void ResetEncoderDecoder(float min, float max)
@@ -57,6 +86,7 @@ private:
 		UF4Counter = 0;
 		randomFluxReversalTime = GenerateRandomFluxReversalTime(min, max);
 	}
+#endif
 	inline void UpdateHeadSectorPosition()
 	{
 		// Disk spins at 300rpm = 5rps so to calculate how many 16Mhz cycles one rotation takes;-
@@ -66,6 +96,12 @@ private:
 		bitsInTrack = diskImage->BitsInTrack(headTrackPos);
 		headBitOffset %= bitsInTrack;
 		cyclesPerBit = CYCLES_16Mhz_PER_ROTATION / (float)bitsInTrack;
+#if defined(EXPERIMENTALZERO)
+		cyclesPerBitInt = cyclesPerBit;
+		cyclesPerBitErrorConstant = (unsigned int)((cyclesPerBit - ((float)cyclesPerBitInt)) * static_cast<float>(0xffffffff));
+		cyclesForBitErrorCounter = (unsigned int)(((cyclesForBit)-(int)(cyclesForBit)) * static_cast<float>(0xffffffff));
+#endif
+
 	}
 
 	inline void MoveHead(unsigned char headDirection)
@@ -88,6 +124,15 @@ private:
 
 	void DumpTrack(unsigned track); // Used for debugging disk images.
 
+#if defined(EXPERIMENTALZERO)
+	inline u32 AdvanceSectorPositionR(int& byteOffset)
+	{
+		if (++headBitOffset == bitsInTrack)
+			headBitOffset = 0;
+		byteOffset = headBitOffset >> 3;
+		return (~headBitOffset) & 7;
+	}
+#else
 	// No reason why I seperate these into individual read and write versions. I was just trying to get the bit stream to line up when rewriting over existing data.
 	inline u32 AdvanceSectorPositionR(int& byteOffset)
 	{
@@ -95,7 +140,7 @@ private:
 		byteOffset = headBitOffset >> 3;
 		return (~headBitOffset) & 7;
 	}
-
+#endif
 	inline u32 AdvanceSectorPositionW(int& byteOffset)
 	{
 		byteOffset = headBitOffset >> 3;
@@ -103,12 +148,24 @@ private:
 		++headBitOffset %= bitsInTrack;
 		return bit;
 	}
-
+	unsigned cachedheadTrackPos = -1;
+	int cachedbyteOffset = -1;
+	unsigned char cachedByte = 0;
 	inline bool GetNextBit()
 	{
 		int byteOffset;
 		int bit = AdvanceSectorPositionR(byteOffset);
-		return diskImage->GetNextBit(headTrackPos, byteOffset, bit);
+
+		//Why is it faster to check both conditions here than to update the cache when moving the head?
+		if (byteOffset != cachedbyteOffset || cachedheadTrackPos != headTrackPos)
+		{
+			cachedByte = diskImage->GetNextByte(headTrackPos, byteOffset);
+			cachedbyteOffset = byteOffset;
+			cachedheadTrackPos = headTrackPos;
+			
+		}
+		return ((cachedByte >> bit) & 1) != 0;
+		//return diskImage->GetNextBit(headTrackPos, byteOffset, bit);
 	}
 
 	inline void SetNextBit(bool value)
@@ -132,13 +189,23 @@ private:
 	// CB2 (output)
 	//	- R/!W
 	m6522* m_pVIA;
-
+#if defined(EXPERIMENTALZERO)
+	unsigned int cyclesLeftForBit;
+	unsigned int fluxReversalCyclesLeft;
+	unsigned int UE7Counter;
+	u32 writeShiftRegister;
+	unsigned int cyclesForBitErrorCounter;
+	unsigned int cyclesPerBitErrorConstant;
+	unsigned int cyclesPerBitInt;
+#else
+	int UE7Counter;
+	u8 writeShiftRegister;
+#endif
 	float cyclesForBit;
 	u32 readShiftRegister;
 	unsigned headTrackPos;
 	u32 headBitOffset;
 	float randomFluxReversalTime;
-	int UE7Counter;
 	int UF4Counter;
 	int UE3Counter;
 	int CLOCK_SEL_AB;
@@ -148,6 +215,5 @@ private:
 	float cyclesPerBit;
 	bool motor;
 	bool LED;
-	u8 writeShiftRegister;
 };
 #endif
diff --git a/src/FileBrowser.cpp b/src/FileBrowser.cpp
index 1f8bd95..b14c186 100644
--- a/src/FileBrowser.cpp
+++ b/src/FileBrowser.cpp
@@ -113,7 +113,6 @@ void FileBrowser::BrowsableListView::RefreshLine(u32 entryIndex, u32 x, u32 y, b
 		}
 		int len = strlen(buffer2 + highlightScrollOffset);
 		strncpy(buffer1, buffer2 + highlightScrollOffset, sizeof(buffer1));
-
 		if (!screen->IsLCD())
 		{
 			// space pad the remainder of the line (but not on OLED)
@@ -121,7 +120,6 @@ void FileBrowser::BrowsableListView::RefreshLine(u32 entryIndex, u32 x, u32 y, b
 				buffer1[len++] = ' ';
 			buffer1[columnsMax] = 0;
 		}
-
 		if (selected)
 		{
 			if (entry->filImage.fattrib & AM_DIR)
@@ -133,7 +131,6 @@ void FileBrowser::BrowsableListView::RefreshLine(u32 entryIndex, u32 x, u32 y, b
 				colour = RGBA(0xff, 0, 0, 0xff);
 				if (entry->filImage.fattrib & AM_RDO)
 					colour = palette[VIC2_COLOUR_INDEX_RED];
-
 				screen->PrintText(false, x, y, buffer1, colour, RGBA(0xff, 0xff, 0xff, 0xff));
 			}
 		}
@@ -499,11 +496,17 @@ FileBrowser::FileBrowser(InputMappings* inputMappings, DiskCaddy* diskCaddy, ROM
 	, roms(roms)
 	, deviceID(deviceID)
 	, displayPNGIcons(displayPNGIcons)
+#if not defined(EXPERIMENTALZERO)
 	, screenMain(screenMain)
+#endif
 	, screenLCD(screenLCD)
 	, scrollHighlightRate(scrollHighlightRate)
 	, displayingDevices(false)
 {
+
+	folder.scrollHighlightRate = scrollHighlightRate;
+
+#if not defined(EXPERIMENTALZERO)
 	u32 columns = screenMain->ScaleX(80);
 	u32 rows = (int)(38.0f * screenMain->GetScaleY());
 	u32 positionX = 0;
@@ -512,7 +515,6 @@ FileBrowser::FileBrowser(InputMappings* inputMappings, DiskCaddy* diskCaddy, ROM
 	if (rows < 1)
 		rows = 1;
 
-	folder.scrollHighlightRate = scrollHighlightRate;
 	folder.AddView(screenMain, inputMappings, columns, rows, positionX, positionY, false);
 
 	positionX = screenMain->ScaleX(1024 - 320);
@@ -520,13 +522,14 @@ FileBrowser::FileBrowser(InputMappings* inputMappings, DiskCaddy* diskCaddy, ROM
 	caddySelections.AddView(screenMain, inputMappings, columns, rows, positionX, positionY, false);
 
 
+#endif
 
 	if (screenLCD)
 	{
-		columns = screenLCD->Width() / 8;
-		rows = screenLCD->Height() / screenLCD->GetFontHeight();
-		positionX = 0;
-		positionY = 0;
+		u32 columns = screenLCD->Width() / 8;
+		u32 rows = screenLCD->Height() / screenLCD->GetFontHeight();
+		u32 positionX = 0;
+		u32 positionY = 0;
 
 		folder.AddView(screenLCD, inputMappings, columns, rows, positionX, positionY, true);
 	}
@@ -690,7 +693,6 @@ void FileBrowser::DeviceSwitched()
 	m_IEC_Commands.SetDisplayingDevices(displayingDevices);
 	FolderChanged();
 }
-
 /*
 void FileBrowser::RefeshDisplayForBrowsableList(FileBrowser::BrowsableList* browsableList, int xOffset, bool showSelected)
 {
@@ -769,9 +771,9 @@ void FileBrowser::RefeshDisplayForBrowsableList(FileBrowser::BrowsableList* brow
 	}
 }
 */
-
 void FileBrowser::RefeshDisplay()
 {
+#if not defined(EXPERIMENTALZERO)
 	u32 textColour = Colour(VIC2_COLOUR_INDEX_LGREEN);
 	u32 bgColour = Colour(VIC2_COLOUR_INDEX_GREY);
 	char buffer[1024];
@@ -780,11 +782,9 @@ void FileBrowser::RefeshDisplay()
 		screenMain->DrawRectangle(0, 0, (int)screenMain->Width(), 17, bgColour);
 		screenMain->PrintText(false, 0, 0, buffer, textColour, bgColour);
 	}
-
 	//u32 offsetX = screenMain->ScaleX(1024 - 320);
 	//RefeshDisplayForBrowsableList(&folder, 0);
 	//RefeshDisplayForBrowsableList(&caddySelections, offsetX, false);
-
 	folder.RefreshViews();
 	caddySelections.RefreshViews();
 
@@ -796,6 +796,10 @@ void FileBrowser::RefeshDisplay()
 		u32 y = screenMain->ScaleY(STATUS_BAR_POSITION_Y);
 		screenMain->PrintText(false, 0, y, folder.searchPrefix, textColour, bgColour);
 	}
+#else
+	folder.RefreshViews();
+	caddySelections.RefreshViews();
+#endif
 }
 
 bool FileBrowser::CheckForPNG(const char* filename, FILINFO& filIcon)
@@ -843,6 +847,8 @@ void FileBrowser::DisplayPNG(FILINFO& filIcon, int x, int y)
 			int h;
 			int channels_in_file;
 			stbi_uc* image = stbi_load_from_memory((stbi_uc const*)PNG, bytesRead, &w, &h, &channels_in_file, 4);
+#if not defined(EXPERIMENTALZERO)
+
 			if (image && (w == PNG_WIDTH && h == PNG_HEIGHT))
 			{
 				//DEBUG_LOG("Opened PNG %s w = %d h = %d cif = %d\r\n", fileName, w, h, channels_in_file);
@@ -852,6 +858,7 @@ void FileBrowser::DisplayPNG(FILINFO& filIcon, int x, int y)
 			{
 				//DEBUG_LOG("Invalid PNG size %d x %d\r\n", w, h);
 			}
+#endif
 		}
 	}
 	else
@@ -862,6 +869,7 @@ void FileBrowser::DisplayPNG(FILINFO& filIcon, int x, int y)
 
 void FileBrowser::DisplayPNG()
 {
+#if not defined(EXPERIMENTALZERO)
 	if (displayPNGIcons && folder.current)
 	{
 		FileBrowser::BrowsableList::Entry* current = folder.current;
@@ -869,6 +877,7 @@ void FileBrowser::DisplayPNG()
 		u32 y = screenMain->ScaleY(666) - PNG_HEIGHT;
 		DisplayPNG(current->filIcon, x, y);
 	}
+#endif
 }
 
 int FileBrowser::IsAtRootOfDevice()
@@ -1369,18 +1378,22 @@ void FileBrowser::UpdateInputDiskCaddy()
 
 void FileBrowser::DisplayStatusBar()
 {
+#if not defined(EXPERIMENTALZERO)
 	u32 x = 0;
 	u32 y = screenMain->ScaleY(STATUS_BAR_POSITION_Y);
 
 	char bufferOut[128];
 	snprintf(bufferOut, 128, "LED 0 Motor 0 Track 18.0 ATN 0 DAT 0 CLK 0");
 	screenMain->PrintText(false, x, y, bufferOut, RGBA(0, 0, 0, 0xff), RGBA(0xff, 0xff, 0xff, 0xff));
+#endif
 }
 
 void FileBrowser::ClearScreen()
 {
+#if not defined(EXPERIMENTALZERO)
 	u32 bgColour = palette[VIC2_COLOUR_INDEX_BLUE];
 	screenMain->Clear(bgColour);
+#endif
 }
 
 void FileBrowser::ClearSelections()
@@ -1397,6 +1410,7 @@ void FileBrowser::ShowDeviceAndROM()
 	u32 textColour = RGBA(0, 0, 0, 0xff);
 	u32 bgColour = RGBA(0xff, 0xff, 0xff, 0xff);
 	u32 x = 0; // 43 * 8
+#if not defined(EXPERIMENTALZERO)
 	u32 y = screenMain->ScaleY(STATUS_BAR_POSITION_Y) - 20;
 
 	snprintf(buffer, 256, "Device %2d %*s\r\n"
@@ -1405,10 +1419,12 @@ void FileBrowser::ShowDeviceAndROM()
 		, roms->ROMNames[roms->currentROMIndex]
 		);
 	screenMain->PrintText(false, x, y, buffer, textColour, bgColour);
+#endif
 }
 
 void FileBrowser::DisplayDiskInfo(DiskImage* diskImage, const char* filenameForIcon)
 {
+#if not defined(EXPERIMENTALZERO)
 	// Ideally we should not have to load the entire disk to read the directory.
 	static const char* fileTypes[]=
 	{
@@ -1626,6 +1642,7 @@ void FileBrowser::DisplayDiskInfo(DiskImage* diskImage, const char* filenameForI
 			DisplayPNG(filIcon, x, y);
 		}
 	}
+#endif
 }
 
 void FileBrowser::SelectAutoMountImage(const char* image)
diff --git a/src/FileBrowser.h b/src/FileBrowser.h
index c5875fc..9a9ec4b 100644
--- a/src/FileBrowser.h
+++ b/src/FileBrowser.h
@@ -84,7 +84,6 @@ public:
 		BrowsableList* list;
 		u32 offset;
 		InputMappings* inputMappings;
-
 		ScreenBase* screen;
 		u32 columns;
 		u32 rows;
@@ -215,9 +214,7 @@ private:
 	//void UpdateInputDiskCaddy();
 
 	void UpdateCurrentHighlight();
-
 	//void RefeshDisplayForBrowsableList(FileBrowser::BrowsableList* browsableList, int xOffset, bool showSelected = true);
-
 	bool FillCaddyWithSelections();
 
 	bool AddToCaddy(FileBrowser::BrowsableList::Entry* current);
@@ -249,10 +246,10 @@ private:
 	bool buttonChangedROMDevice;
 
 	BrowsableList caddySelections;
-
+#if not defined(EXPERIMENTALZERO)
 	ScreenBase* screenMain;
+#endif
 	ScreenBase* screenLCD;
-
 	float scrollHighlightRate;
 
 	bool displayingDevices;
diff --git a/src/InputMappings.cpp b/src/InputMappings.cpp
index 541045c..1a138a0 100644
--- a/src/InputMappings.cpp
+++ b/src/InputMappings.cpp
@@ -1,3 +1,4 @@
+
 // Pi1541 - A Commodore 1541 disk drive emulator
 // Copyright(C) 2018 Stephen White
 //
@@ -217,9 +218,11 @@ void InputMappings::CheckButtonsEmulationMode()
 
 bool InputMappings::CheckKeyboardBrowseMode()
 {
+#if not defined(EXPERIMENTALZERO)
 	Keyboard* keyboard = Keyboard::Instance();
-
+#endif
 	keyboardFlags = 0;
+#if not defined(EXPERIMENTALZERO)
 	keyboardNumLetter = 0;
 	if (!keyboard->CheckChanged())
 	{
@@ -305,12 +308,13 @@ bool InputMappings::CheckKeyboardBrowseMode()
 			}
 		}
 	}
-
+#endif
 	return keyboardFlags != 0;
 }
 
 void InputMappings::CheckKeyboardEmulationMode(unsigned numberOfImages, unsigned numberOfImagesMax)
 {
+#if not defined(EXPERIMENTALZERO)
 	Keyboard* keyboard = Keyboard::Instance();
 
 	keyboardFlags = 0;
@@ -341,5 +345,6 @@ void InputMappings::CheckKeyboardEmulationMode(unsigned numberOfImages, unsigned
 				directDiskSwapRequest |= (1 << index);
 		}
 	}
+#endif
 }
 
diff --git a/src/InputMappings.h b/src/InputMappings.h
index e0dad43..7cdf5c6 100644
--- a/src/InputMappings.h
+++ b/src/InputMappings.h
@@ -103,21 +103,37 @@ public:
 		keyboardBrowseLCDScreen = value;
 	}
 
+#if defined(EXPERIMENTALZERO)
 	inline bool Exit()
 	{
-		return KeyboardFlag(ESC_FLAG)/* | UartFlag(ESC_FLAG)*/ | ButtonFlag(ESC_FLAG);
+		return ButtonFlag(ESC_FLAG);
 	}
 
 	inline bool NextDisk()
 	{
-		return KeyboardFlag(NEXT_FLAG)/* | UartFlag(NEXT_FLAG)*/ | ButtonFlag(NEXT_FLAG);
+		return ButtonFlag(NEXT_FLAG);
 	}
 
 	inline bool PrevDisk()
 	{
-		return KeyboardFlag(PREV_FLAG)/* | UartFlag(PREV_FLAG)*/ | ButtonFlag(PREV_FLAG);
+		return ButtonFlag(PREV_FLAG);
+	}
+#else
+	inline bool Exit()
+	{
+		return KeyboardFlag(ESC_FLAG) | /*UartFlag(ESC_FLAG) |*/ ButtonFlag(ESC_FLAG);
 	}
 
+	inline bool NextDisk()
+	{
+		return KeyboardFlag(NEXT_FLAG) | /*UartFlag(NEXT_FLAG) |*/ ButtonFlag(NEXT_FLAG);
+	}
+
+	inline bool PrevDisk()
+	{
+		return KeyboardFlag(PREV_FLAG) | /*UartFlag(PREV_FLAG) |*/ ButtonFlag(PREV_FLAG);
+	}
+#endif
 	inline bool AutoLoad() { return KeyboardFlag(AUTOLOAD_FLAG); }
 
 	inline bool FakeReset() { return KeyboardFlag(FAKERESET_FLAG); }
diff --git a/src/Keyboard.cpp b/src/Keyboard.cpp
index c3f843c..01c2b7d 100644
--- a/src/Keyboard.cpp
+++ b/src/Keyboard.cpp
@@ -15,7 +15,7 @@
 // 
 // You should have received a copy of the GNU General Public License
 // along with Pi1541. If not, see <http://www.gnu.org/licenses/>.
-
+#if not defined(EXPERIMENTALZERO)
 #include "Keyboard.h"
 #include <string.h>
 #include <uspi.h>
@@ -156,3 +156,4 @@ Keyboard::Keyboard()
 	memset(keyRepeatCount, 0, sizeof(keyRepeatCount));
 	USPiKeyboardRegisterKeyStatusHandlerRaw(KeyPressedHandlerRaw);
 }
+#endif
diff --git a/src/Keyboard.h b/src/Keyboard.h
index cfbd1e6..b0e9b0c 100644
--- a/src/Keyboard.h
+++ b/src/Keyboard.h
@@ -24,6 +24,7 @@ extern "C"
 {
 #include <uspi/usbkeyboard.h>
 }
+#if not defined(EXPERIMENTALZERO)
 
 #define MAX_KEYS 0x7f
 
@@ -356,3 +357,4 @@ public:
 	static Keyboard* instance;
 };
 #endif
+#endif
\ No newline at end of file
diff --git a/src/Pi1581.cpp b/src/Pi1581.cpp
index a581e26..930ab5a 100644
--- a/src/Pi1581.cpp
+++ b/src/Pi1581.cpp
@@ -93,6 +93,7 @@ extern u16 pc;
 u8 read6502_1581(u16 address)
 {
 	u8 value = 0;
+#if defined(PI1581SUPPORT)
 	if (address & 0x8000)
 	{
 		value = roms.Read1581(address);
@@ -115,6 +116,7 @@ u8 read6502_1581(u16 address)
 	{
 		value = address >> 8;	// Empty address bus
 	}
+#endif
 	return value;
 }
 
@@ -127,6 +129,7 @@ u8 peek6502_1581(u16 address)
 
 void write6502_1581(u16 address, const u8 value)
 {
+#if defined(PI1581SUPPORT)
 	if (address & 0x8000)
 	{
 		return;
@@ -145,6 +148,7 @@ void write6502_1581(u16 address, const u8 value)
 	{
 		s_u8Memory[address & 0x1fff] = value;
 	}
+#endif
 }
 
 static void CIAPortA_OnPortOut(void* pUserData, unsigned char status)
diff --git a/src/Screen.cpp b/src/Screen.cpp
index 999718d..6118b5d 100644
--- a/src/Screen.cpp
+++ b/src/Screen.cpp
@@ -129,21 +129,29 @@ void Screen::Open(u32 widthDesired, u32 heightDesired, u32 colourDepth)
 
 void Screen::PlotPixel32(u32 pixel_offset, RGBA Colour)
 {
+#if not defined(EXPERIMENTALZERO)
 	*((volatile RGBA*)&framebuffer[pixel_offset]) = Colour;
+#endif
 }
 void Screen::PlotPixel24(u32 pixel_offset, RGBA Colour)
 {
+#if not defined(EXPERIMENTALZERO)
 	framebuffer[pixel_offset++] = BLUE(Colour);
 	framebuffer[pixel_offset++] = GREEN(Colour);
 	framebuffer[pixel_offset++] = RED(Colour);
+#endif
 }
 void Screen::PlotPixel16(u32 pixel_offset, RGBA Colour)
 {
+#if not defined(EXPERIMENTALZERO)
 	*(unsigned short*)&framebuffer[pixel_offset] = ((RED(Colour) >> 3) << 11) | ((GREEN(Colour) >> 2) << 5) | (BLUE(Colour) >> 3);
+#endif
 }
 void Screen::PlotPixel8(u32 pixel_offset, RGBA Colour)
 {
+#if not defined(EXPERIMENTALZERO)
 	framebuffer[pixel_offset++] = RED(Colour);
+#endif
 }
 
 void Screen::DrawRectangle(u32 x1, u32 y1, u32 x2, u32 y2, RGBA colour)
diff --git a/src/armc-cstubs.c b/src/armc-cstubs.c
index 8fb4e29..7b16f20 100644
--- a/src/armc-cstubs.c
+++ b/src/armc-cstubs.c
@@ -236,7 +236,9 @@ int wait(int *status)
 
 void outbyte(char b)
 {
+#ifndef EXPERIMENTALZERO
   RPI_AuxMiniUartWrite(b);
+#endif
 }
 
 /* Write to a file. libc subroutines will use this system routine for output to
diff --git a/src/defs.h b/src/defs.h
index 7462bdb..1e6f84d 100644
--- a/src/defs.h
+++ b/src/defs.h
@@ -2,7 +2,9 @@
 #define DEFS_H
 
 #include "debug.h"
-
+#ifndef EXPERIMENTALZERO
+#define PI1581SUPPORT 1
+#endif
 // Indicates a Pi with the 40 pin GPIO connector
 // so that additional functionality (e.g. test pins) can be enabled
 #if defined(RPIZERO) || defined(RPIBPLUS) || defined(RPI2) || defined(RPI3)
diff --git a/src/iec_bus.cpp b/src/iec_bus.cpp
index e77c468..a6bd0ef 100644
--- a/src/iec_bus.cpp
+++ b/src/iec_bus.cpp
@@ -335,10 +335,10 @@ void IEC_Bus::RefreshOuts1541(void)
 
 	if (OutputLED) set |= 1 << PIGPIO_OUT_LED;
 	else clear |= 1 << PIGPIO_OUT_LED;
-
+#if not defined(EXPERIMENTALZERO)
 	if (OutputSound) set |= 1 << PIGPIO_OUT_SOUND;
 	else clear |= 1 << PIGPIO_OUT_SOUND;
-
+#endif
 	if (oldClears != clear)
 	{
 		write32(ARM_GPIO_GPCLR0, clear);
diff --git a/src/iec_bus.h b/src/iec_bus.h
index 76f2a98..b6eb057 100644
--- a/src/iec_bus.h
+++ b/src/iec_bus.h
@@ -135,6 +135,7 @@ enum PIGPIOMasks
 	PIGPIO_MASK_IN_BUTTON3 = 1 << PIGPIO_IN_BUTTON3,
 	PIGPIO_MASK_IN_BUTTON4 = 1 << PIGPIO_IN_BUTTON4,
 	PIGPIO_MASK_IN_BUTTON5 = 1 << PIGPIO_IN_BUTTON5,
+	PIGPIO_MASK_ANY_BUTTON = PIGPIO_MASK_IN_BUTTON1 | PIGPIO_MASK_IN_BUTTON2 | PIGPIO_MASK_IN_BUTTON3 | PIGPIO_MASK_IN_BUTTON4 | PIGPIO_MASK_IN_BUTTON5
 };
 
 static const unsigned ButtonPinFlags[5] = { PIGPIO_MASK_IN_BUTTON1, PIGPIO_MASK_IN_BUTTON2, PIGPIO_MASK_IN_BUTTON3, PIGPIO_MASK_IN_BUTTON4, PIGPIO_MASK_IN_BUTTON5 };
@@ -276,7 +277,7 @@ public:
 			RPI_SetGpioPinFunction((rpi_gpio_pin_t)PIGPIO_OUT_SRQ, FS_OUTPUT);
 		}
 	
-
+#if not defined(EXPERIMENTALZERO)
 		// Set up audio.
 		write32(CM_PWMDIV, CM_PASSWORD + 0x2000);
 		write32(CM_PWMCTL, CM_PASSWORD + CM_ENAB + CM_SRC_OSCILLATOR);	// Use Default 100MHz Clock
@@ -284,7 +285,7 @@ public:
 		write32(PWM_RNG1, 0x1B4);	// 8bit 44100Hz Mono
 		write32(PWM_RNG2, 0x1B4);
 		write32(PWM_CTL, PWM_USEF2 + PWM_PWEN2 + PWM_USEF1 + PWM_PWEN1 + PWM_CLRF1);
-
+#endif
 
 		int buttonCount = sizeof(ButtonPinFlags) / sizeof(unsigned);
 		for (index = 0; index < buttonCount; ++index)
@@ -316,6 +317,13 @@ public:
 		RefreshOuts1581();
 	}
 
+#if defined(EXPERIMENTALZERO)
+	static inline bool AnyButtonPressed()
+	{
+		return ((gplev0 & PIGPIO_MASK_ANY_BUTTON) != PIGPIO_MASK_ANY_BUTTON);
+	}
+#endif
+
 	static inline void UpdateButton(int index, unsigned gplev0)
 	{
 		bool inputcurrent = (gplev0 & ButtonPinFlags[index]) == 0;
diff --git a/src/interrupt.c b/src/interrupt.c
index 31694e7..ad5fa08 100644
--- a/src/interrupt.c
+++ b/src/interrupt.c
@@ -39,16 +39,21 @@ void InterruptSystemInitialize()
 	write32(ARM_IC_IRQ_PENDING_2, read32(ARM_IC_IRQ_PENDING_2));
 
 	DataMemBarrier();
-
+#ifdef EXPERIMENTALZERO
+	DisableInterrupts();
+#else
 	EnableInterrupts();
+#endif
 }
 
 void InterruptSystemConnectIRQ(unsigned IRQIndex, IRQHandler* handler, void* param)
 {
+#ifndef EXPERIMENTALZERO
 	IRQHandlers[IRQIndex] = handler;
 	Params[IRQIndex] = param;
 
 	InterruptSystemEnableIRQ(IRQIndex);
+#endif
 }
 
 void InterruptSystemDisconnectIRQ(unsigned IRQIndex)
@@ -61,10 +66,12 @@ void InterruptSystemDisconnectIRQ(unsigned IRQIndex)
 
 void InterruptSystemEnableIRQ(unsigned IRQIndex)
 {
-	//DEBUG_LOG("InterruptSystemEnableIRQ %d\r\n", IRQIndex);
+#ifndef EXPERIMENTALZERO
+	DEBUG_LOG("InterruptSystemEnableIRQ %d\r\n", IRQIndex);
 	DataMemBarrier();
 	write32(ARM_IC_IRQS_ENABLE(IRQIndex), ARM_IRQ_MASK(IRQIndex));
 	DataMemBarrier();
+#endif
 }
 
 void InterruptSystemDisableIRQ(unsigned IRQIndex)
@@ -110,11 +117,13 @@ void InterruptHandler(void)
 
 		if (pendValue & IRQIndexMask)
 		{
+#ifndef EXPERIMENTALZERO
 			IRQHandler* pHandler = IRQHandlers[IRQIndex];
 
 			if (pHandler != 0)
 				(*pHandler)(Params[IRQIndex]);
 			else
+#endif
 				InterruptSystemDisableIRQ(IRQIndex);
 		}
 	}
@@ -127,11 +136,13 @@ void InterruptHandler(void)
 
 		if (pendValue & IRQIndexMask)
 		{
+#ifndef EXPERIMENTALZERO
 			IRQHandler* pHandler = IRQHandlers[IRQIndex];
 
 			if (pHandler != 0)
 				(*pHandler)(Params[IRQIndex]);
 			else
+#endif
 				InterruptSystemDisableIRQ(IRQIndex);
 		}
 	}
@@ -144,11 +155,13 @@ void InterruptHandler(void)
 
 		if (pendValue & IRQIndexMask)
 		{
+#ifndef EXPERIMENTALZERO
 			IRQHandler* pHandler = IRQHandlers[IRQIndex];
 
 			if (pHandler != 0)
 				(*pHandler)(Params[IRQIndex]);
 			else
+#endif
 				InterruptSystemDisableIRQ(IRQIndex);
 		}
 	}
diff --git a/src/interrupt.h b/src/interrupt.h
index 0dcfb93..f917ddd 100644
--- a/src/interrupt.h
+++ b/src/interrupt.h
@@ -9,7 +9,7 @@ extern "C" {
 #include "bcm2835int.h"
 
 #define	EnableInterrupts()	__asm volatile ("cpsie i")
-#define	DisableInterrupts()	__asm volatile ("cpsid i")
+#define	DisableInterrupts()	__asm volatile ("cpsid ifa, #0x13")
 
 typedef void IRQHandler(void* param);
 
diff --git a/src/main.cpp b/src/main.cpp
index c5bcd9b..33aee90 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -101,7 +101,9 @@ u8 s_u8Memory[0xc000];
 int numberOfUSBMassStorageDevices = 0;
 DiskCaddy diskCaddy;
 Pi1541 pi1541;
+#if defined(PI1581SUPPORT)
 Pi1581 pi1581;
+#endif
 CEMMCDevice	m_EMMC;
 Screen screen;
 ScreenLCD* screenLCD = 0;
@@ -110,14 +112,17 @@ const char* fileBrowserSelectedName;
 u8 deviceID = 8;
 IEC_Commands m_IEC_Commands;
 InputMappings* inputMappings;
+#if not defined(EXPERIMENTALZERO)
 Keyboard* keyboard;
+#endif
 bool USBKeyboardDetected = false;
 //bool resetWhileEmulating = false;
 bool selectedViaIECCommands = false;
 u16 pc;
 
+#if not defined(EXPERIMENTALZERO)
 SpinLock core0RefreshingScreen;
-
+#endif
 unsigned int screenWidth = 1024;
 unsigned int screenHeight = 768;
 
@@ -225,8 +230,9 @@ void InitialiseHardware()
 	RPI_TouchInit();
 #endif
 
+#if not defined(EXPERIMENTALZERO)
 	screen.Open(screenWidth, screenHeight, 16);
-
+#endif
 	RPI_PropertyInit();
 	RPI_PropertyAddTag(TAG_GET_MAX_CLOCK_RATE, ARM_CLK_ID);
 	RPI_PropertyProcess();
@@ -244,7 +250,6 @@ void InitialiseHardware()
 
 void InitialiseLCD()
 {
-
 	FILINFO filLcdIcon;
 
 	int i2cBusMaster = options.I2CBusMaster();
@@ -326,6 +331,7 @@ void InitialiseLCD()
 // Care must be taken not to crowd out the shared cache with core1 as this could slow down core1 so that it no longer can perform its duties in the 1us timings it requires.
 void UpdateScreen()
 {
+#if not defined(EXPERIMENTALZERO)
 	bool oldLED = false;
 	bool oldMotor = false;
 	bool oldATN = false;
@@ -555,6 +561,7 @@ void UpdateScreen()
 		// Go back to sleep. The USB irq will wake us up again.
 		__asm ("WFE");
 	}
+#endif
 }
 
 static bool Snoop(u8 a)
@@ -603,6 +610,7 @@ EmulatingMode BeginEmulating(FileBrowser* fileBrowser, const char* filenameForIc
 	DiskImage* diskImage = diskCaddy.SelectFirstImage();
 	if (diskImage)
 	{
+#if defined(PI1581SUPPORT)
 		if (diskImage->IsD81())
 		{
 			pi1581.Insert(diskImage);
@@ -611,6 +619,7 @@ EmulatingMode BeginEmulating(FileBrowser* fileBrowser, const char* filenameForIc
 			return EMULATING_1581;
 		}
 		else
+#endif
 		{
 			pi1541.drive.Insert(diskImage);
 			fileBrowser->DisplayDiskInfo(diskImage, filenameForIcon);
@@ -621,7 +630,7 @@ EmulatingMode BeginEmulating(FileBrowser* fileBrowser, const char* filenameForIc
 	inputMappings->WaitForClearButtons();
 	return IEC_COMMANDS;
 }
-
+#if not defined(EXPERIMENTALZERO)
 static u32* dmaSound;
 
 struct DMA_ControlBlock
@@ -646,13 +655,15 @@ DMA_ControlBlock dmaSoundCB =
 	0,//&dmaSoundCB,
 	0, 0
 };
-
+#endif
 static void PlaySoundDMA()
 {
+#if not defined(EXPERIMENTALZERO)
 	write32(PWM_DMAC, PWM_ENAB + 0x0001);
 	write32(DMA_ENABLE, 1);	// DMA_EN0
 	write32(DMA0_BASE + DMA_CONBLK_AD, (u32)&dmaSoundCB);
 	write32(DMA0_BASE + DMA_CS, DMA_ACTIVE);
+#endif
 }
 
 void GlobalSetDeviceID(u8 id)
@@ -660,7 +671,9 @@ void GlobalSetDeviceID(u8 id)
 	deviceID = id;
 	m_IEC_Commands.SetDeviceId(id);
 	pi1541.SetDeviceID(id);
+#if defined(PI1581SUPPORT)
 	pi1581.SetDeviceID(id);
+#endif
 }
 
 void CheckAutoMountImage(EXIT_TYPE reset_reason , FileBrowser* fileBrowser)
@@ -684,6 +697,156 @@ void CheckAutoMountImage(EXIT_TYPE reset_reason , FileBrowser* fileBrowser)
 	}
 }
 
+#if defined(EXPERIMENTALZERO)
+EXIT_TYPE Emulate1541(FileBrowser* fileBrowser)
+{
+	bool oldLED = false;
+	unsigned ctBefore = 0;
+	unsigned ctAfter = 0;
+	int cycleCount = 0;
+	unsigned caddyIndex;
+	int headSoundCounter = 0;
+	int headSoundFreqCounter = 0;
+	//			const int headSoundFreq = 833;	// 1200Hz = 1/1200 * 10^6;
+	const int headSoundFreq = 1000000 / options.SoundOnGPIOFreq();	// 1200Hz = 1/1200 * 10^6;
+	unsigned char oldHeadDir;
+	int resetCount = 0;
+	bool refreshOutsAfterCPUStep = true;
+	unsigned numberOfImages = diskCaddy.GetNumberOfImages();
+	unsigned numberOfImagesMax = numberOfImages;
+	if (numberOfImagesMax > 10)
+		numberOfImagesMax = 10;
+
+	diskCaddy.Display();
+
+	inputMappings->directDiskSwapRequest = 0;
+	// Force an update on all the buttons now before we start emulation mode. 
+	IEC_Bus::ReadBrowseMode();
+
+	bool extraRAM = options.GetExtraRAM();
+	DataBusReadFn dataBusRead = extraRAM ? read6502ExtraRAM : read6502;
+	DataBusWriteFn dataBusWrite = extraRAM ? write6502ExtraRAM : write6502;
+	M6502& m6502 = pi1541.m6502;
+	m6502.SetBusFunctions(dataBusRead, dataBusWrite);
+
+	IEC_Bus::VIA = &pi1541.VIA[0];
+	IEC_Bus::port = pi1541.VIA[0].GetPortB();
+	pi1541.Reset();	// will call IEC_Bus::Reset();
+	IEC_Bus::OutputLED = false;
+	IEC_Bus::LetSRQBePulledHigh();
+	ctBefore = read32(ARM_SYSTIMER_CLO);
+
+	//resetWhileEmulating = false;
+	selectedViaIECCommands = false;
+
+	u32 hash = pi1541.drive.GetDiskImage()->GetHash();
+	// 0x42c02586 = maniac_mansion_s1[lucasfilm_1989](ntsc).g64
+	// 0x18651422 = aliens[electric_dreams_1987].g64
+	// 0x2a7f4b77 = zak_mckracken_boot[activision_1988](manual)(!).g64
+	if (hash == 0x42c02586 || hash == 0x18651422 || hash == 0x2a7f4b77)
+	{
+		refreshOutsAfterCPUStep = false;
+	}
+
+	while (cycleCount < FAST_BOOT_CYCLES)
+	{
+		m6502.Step();
+		pi1541.Update();
+		cycleCount++;
+		IEC_Bus::ReadEmulationMode1541();
+	}
+	bool buttonState = false;
+	bool prevButtonState = false;
+	while (true)
+	{
+
+		if (m6502.SYNC())	// About to start a new instruction.
+		{
+			pc = m6502.GetPC();
+			// See if the emulated cpu is executing CD:_ (ie back out of emulated image)
+			if (snoopIndex == 0 && (pc == SNOOP_CD_CBM || pc == SNOOP_CD_JIFFY_BOTH || pc == SNOOP_CD_JIFFY_DRIVEONLY)) snoopPC = pc;
+
+			if (pc == snoopPC)
+			{
+				if (Snoop(m6502.GetA()))
+				{
+					return EXIT_CD;
+				}
+			}
+		}
+
+		m6502.Step();	// If the CPU reads or writes to the VIA then clk and data can change
+
+		if (refreshOutsAfterCPUStep)
+			IEC_Bus::RefreshOuts1541();	// Now output all outputs.
+
+		IEC_Bus::OutputLED = pi1541.drive.IsLEDOn();
+		if (IEC_Bus::OutputLED ^ oldLED)
+		{
+			SetACTLed(IEC_Bus::OutputLED);
+			oldLED = IEC_Bus::OutputLED;
+		}
+
+		pi1541.Update();
+
+		if (__builtin_expect(IEC_Bus::IsReset(), false))
+			resetCount++;
+		else
+			resetCount = 0;
+
+		if ((resetCount > 10))
+		{
+			return EXIT_RESET;
+		}
+
+		buttonState = IEC_Bus::AnyButtonPressed();
+		if (__builtin_expect(buttonState, false))
+		{
+			IEC_Bus::ReadButtonsEmulationMode();
+			inputMappings->CheckButtonsEmulationMode();
+			if (numberOfImages > 1)
+			{
+				bool nextDisk = inputMappings->NextDisk();
+				bool prevDisk = inputMappings->PrevDisk();
+				if (nextDisk)
+				{
+					pi1541.drive.Insert(diskCaddy.PrevDisk());
+				}
+				if (prevDisk)
+				{
+					pi1541.drive.Insert(diskCaddy.NextDisk());
+				}
+			}
+			bool exitEmulation = inputMappings->Exit();
+			if (exitEmulation)
+				return EXIT_KEYBOARD;
+		}
+		else if (__builtin_expect(!buttonState & prevButtonState, false))
+		{
+			IEC_Bus::ReadButtonsEmulationMode();
+			inputMappings->CheckButtonsEmulationMode();
+		}
+
+		prevButtonState = buttonState;
+
+		do
+		{
+			ctAfter = read32(ARM_SYSTIMER_CLO);
+		} while (ctAfter == ctBefore); 	// Sync to the 1MHz clock
+	
+
+		ctBefore = ctAfter;		
+		IEC_Bus::ReadEmulationMode1541();
+
+		IEC_Bus::RefreshOuts1541();	// Now output all outputs.
+
+
+
+	}
+	return EXIT_UNKNOWN;
+}
+
+#else
 EXIT_TYPE Emulate1541(FileBrowser* fileBrowser)
 {
 	EXIT_TYPE exitReason = EXIT_UNKNOWN;
@@ -890,7 +1053,9 @@ EXIT_TYPE Emulate1541(FileBrowser* fileBrowser)
 	}
 	return exitReason;
 }
+#endif
 
+#if defined(PI1581SUPPORT)
 EXIT_TYPE Emulate1581(FileBrowser* fileBrowser)
 {
 	EXIT_TYPE exitReason = EXIT_UNKNOWN;
@@ -1075,10 +1240,13 @@ EXIT_TYPE Emulate1581(FileBrowser* fileBrowser)
 	}
 	return exitReason;
 }
+#endif
 
 void emulator()
 {
+#if not defined(EXPERIMENTALZERO)
 	Keyboard* keyboard = Keyboard::Instance();
+#endif
 	FileBrowser* fileBrowser;
 	EXIT_TYPE exitReason = EXIT_UNKNOWN;
 
@@ -1095,7 +1263,6 @@ void emulator()
 	m_IEC_Commands.SetNewDiskType(options.GetNewDiskType());
 
 	emulating = IEC_COMMANDS;
-
 	while (1)
 	{
 		if (emulating == IEC_COMMANDS)
@@ -1107,8 +1274,9 @@ void emulator()
 			IEC_Bus::Reset();
 
 			IEC_Bus::LetSRQBePulledHigh();
-
+#if not defined(EXPERIMENTALZERO)
 			core0RefreshingScreen.Acquire();
+#endif
 			IEC_Bus::WaitMicroSeconds(100);
 
 			roms.ResetCurrentROMIndex();
@@ -1118,14 +1286,15 @@ void emulator()
 			fileBrowser->ClearSelections();
 
 			fileBrowser->RefeshDisplay(); // Just redisplay the current folder.
-
+#if not defined(EXPERIMENTALZERO)
 			core0RefreshingScreen.Release();
-
+#endif
 			selectedViaIECCommands = false;
 
 			inputMappings->Reset();
+#if not defined(EXPERIMENTALZERO)
 			inputMappings->SetKeyboardBrowseLCDScreen(screenLCD && options.KeyboardBrowseLCDScreen());
-
+#endif
 			fileBrowser->ShowDeviceAndROM();
 
 			if (!options.GetDisableSD2IECCommands())
@@ -1149,7 +1318,6 @@ void emulator()
 							break;
 						case IEC_Commands::NONE:
 							fileBrowser->Update();
-
 							// Check selections made via FileBrowser
 							if (fileBrowser->SelectionsMade())
 								emulating = BeginEmulating(fileBrowser, fileBrowser->LastSelectionName());
@@ -1210,7 +1378,7 @@ void emulator()
 							fileBrowser->ShowDeviceAndROM();
 							break;
 						case IEC_Commands::DEVICE_SWITCHED:
-							DEBUG_LOG("DEVICE_SWITCHED\r\n");
+							DEBUG_LOG("DECIVE_SWITCHED\r\n");
 							fileBrowser->DeviceSwitched();
 							break;
 						default:
@@ -1234,8 +1402,10 @@ void emulator()
 		{
 			if (emulating == EMULATING_1541)
 				exitReason = Emulate1541(fileBrowser);
+#if defined(PI1581SUPPORT)
 			else
 				exitReason = Emulate1581(fileBrowser);
+#endif
 
 			DEBUG_LOG("Exited emulation\r\n");
 
@@ -1320,6 +1490,7 @@ static bool AttemptToLoadROM(char* ROMName)
 
 static void DisplayLogo()
 {
+#if not defined(EXPERIMENTALZERO)
 	int w;
 	int h;
 	int channels_in_file;
@@ -1329,6 +1500,7 @@ static void DisplayLogo()
 
 	snprintf(tempBuffer, tempBufferSize, "V%d.%02d", versionMajor, versionMinor);
 	screen.PrintText(false, 20, 180, tempBuffer, FileBrowser::Colour(VIC2_COLOUR_INDEX_BLUE));
+#endif
 }
 
 static void LoadOptions()
@@ -1354,6 +1526,7 @@ static void LoadOptions()
 
 void DisplayOptions(int y_pos)
 {
+#if not defined(EXPERIMENTALZERO)
 	// print confirmation of parsed options
 	snprintf(tempBuffer, tempBufferSize, "ignoreReset = %d\r\n", options.IgnoreReset());
 	screen.PrintText(false, 0, y_pos += 16, tempBuffer, COLOUR_WHITE, COLOUR_BLACK);
@@ -1375,10 +1548,12 @@ void DisplayOptions(int y_pos)
 	screen.PrintText(false, 0, y_pos += 16, tempBuffer, COLOUR_WHITE, COLOUR_BLACK);
 	snprintf(tempBuffer, tempBufferSize, "AutoBaseName = %s\r\n", options.GetAutoBaseName());
 	screen.PrintText(false, 0, y_pos += 16, tempBuffer, COLOUR_WHITE, COLOUR_BLACK);
+#endif
 }
 
 void DisplayI2CScan(int y_pos)
 {
+#if not defined(EXPERIMENTALZERO)
 	int BSCMaster = options.I2CBusMaster();
 
 	snprintf(tempBuffer, tempBufferSize, "Scanning i2c bus %d ...\r\n", BSCMaster);
@@ -1401,6 +1576,7 @@ void DisplayI2CScan(int y_pos)
 		ptr += snprintf (tempBuffer+ptr, tempBufferSize-ptr, "Nothing");
 
 	screen.PrintText(false, 0, y_pos+16, tempBuffer, COLOUR_WHITE, COLOUR_BLACK);
+#endif
 }
 
 static void CheckOptions()
@@ -1415,7 +1591,7 @@ static void CheckOptions()
 
 	deviceID = (u8)options.GetDeviceID();
 	DEBUG_LOG("DeviceID = %d\r\n", deviceID);
-
+#if not defined(EXPERIMENTALZERO)
 	const char* FontROMName = options.GetRomFontName();
 	if (FontROMName)
 	{
@@ -1450,7 +1626,7 @@ static void CheckOptions()
 			//DEBUG_LOG("Read ROM %s from options\r\n", ROMName);
 		}
 	}
-
+#endif
 	const char* ROMName1581 = options.GetRomName1581();
 	if (ROMName1581)
 	{
@@ -1522,6 +1698,7 @@ static void CheckOptions()
 		}
 	}
 
+
 	if (roms.ROMValid[0] == false && !(AttemptToLoadROM("d1541.rom") || AttemptToLoadROM("dos1541") || AttemptToLoadROM("d1541II") || AttemptToLoadROM("Jiffy.bin")))
 	{
 		snprintf(tempBuffer, tempBufferSize, "No ROM file found!\r\nPlease copy a valid 1541 ROM file in the root folder of the SD card.\r\nThe file needs to be called 'dos1541'.");
@@ -1563,6 +1740,7 @@ bool SwitchDrive(const char* drive)
 
 void UpdateFirmwareToSD()
 {
+#if not defined(EXPERIMENTALZERO)
 	const char* firmwareName = "kernel.img";
 	DIR dir;
 	FILINFO filInfo;
@@ -1658,10 +1836,12 @@ void UpdateFirmwareToSD()
 			f_chdir(cwd);
 		}
 	}
+#endif
 }
 
 void DisplayMessage(int x, int y, bool LCD, const char* message, u32 textColour, u32 backgroundColour)
 {
+#if not defined(EXPERIMENTALZERO)
 	char buffer[256] = { 0 };
 
 	if (!LCD)
@@ -1682,8 +1862,15 @@ void DisplayMessage(int x, int y, bool LCD, const char* message, u32 textColour,
 		screenLCD->SwapBuffers();
 
 		core0RefreshingScreen.Release();
-
 	}
+#else
+	RGBA BkColour = RGBA(0, 0, 0, 0xFF);
+
+	screenLCD->Clear(BkColour);
+	screenLCD->PrintText(false, x, y, (char*)message, textColour, backgroundColour);
+	screenLCD->SwapBuffers();
+
+#endif
 }
 
 extern "C"
@@ -1699,8 +1886,9 @@ extern "C"
 		disk_setEMM(&m_EMMC);
 		f_mount(&fileSystemSD, "SD:", 1);
 
+#if not defined(EXPERIMENTALZERO)
 		RPI_AuxMiniUartInit(115200, 8);
-
+#endif
 		LoadOptions();
 
 		InitialiseHardware();
@@ -1712,7 +1900,7 @@ extern "C"
 		DisplayLogo();
 
 		InitialiseLCD();
-
+#if not defined(EXPERIMENTALZERO)
 		int y_pos = 184;
 		snprintf(tempBuffer, tempBufferSize, "Copyright(C) 2018 Stephen White");
 		screen.PrintText(false, 0, y_pos+=16, tempBuffer, COLOUR_WHITE, COLOUR_BLACK);
@@ -1727,10 +1915,12 @@ extern "C"
 		if (options.ShowOptions())
 			DisplayOptions(y_pos+=32);
 
+#endif
 		//if (!options.QuickBoot())
-		//	IEC_Bus::WaitMicroSeconds(3 * 1000000);
+			//IEC_Bus::WaitMicroSeconds(3 * 1000000);
 
 		InterruptSystemInitialize();
+#if not defined(EXPERIMENTALZERO)
 		TimerSystemInitialize();
 
 		USPiInitialize();
@@ -1752,6 +1942,7 @@ extern "C"
 		//	DEBUG_LOG("Mouse found\r\n");
 
 		keyboard = new Keyboard();
+#endif
 		inputMappings = new InputMappings();
 		//USPiMouseRegisterStatusHandler(MouseHandler);
 
@@ -1762,7 +1953,7 @@ extern "C"
 		IEC_Bus::SetInvertIECInputs(options.InvertIECInputs());
 		IEC_Bus::SetInvertIECOutputs(options.InvertIECOutputs());
 		IEC_Bus::SetIgnoreReset(options.IgnoreReset());
-
+#if not defined(EXPERIMENTALZERO)
 		if (!options.SoundOnGPIO())
 		{
 			dmaSound = (u32*)malloc(Sample_bin_size * 4);
@@ -1786,7 +1977,7 @@ extern "C"
 			if (SwitchDrive("USB01:"))
 				UpdateFirmwareToSD();
 		}
-
+#endif
 		f_chdir("/1541");
 
 		m_IEC_Commands.SetStarFileName(options.GetStarFileName());
@@ -1795,9 +1986,7 @@ extern "C"
 
 		pi1541.drive.SetVIA(&pi1541.VIA[1]);
 		pi1541.VIA[0].GetPortB()->SetPortOut(0, IEC_Bus::PortB_OnPortOut);
-
 		IEC_Bus::Initialise();
-
 		if (screenLCD)
 			screenLCD->ClearInit(0);
 
diff --git a/src/options.h b/src/options.h
index 0aa41fb..bafb5f1 100644
--- a/src/options.h
+++ b/src/options.h
@@ -63,7 +63,11 @@ public:
 	inline unsigned int QuickBoot() const { return quickBoot; }
 	inline unsigned int ShowOptions() const { return showOptions; }
 	inline unsigned int DisplayPNGIcons() const { return displayPNGIcons; }
+#if defined(EXPERIMENTALZERO)
+	inline unsigned int SoundOnGPIO() const { return false; }
+#else
 	inline unsigned int SoundOnGPIO() const { return soundOnGPIO; }
+#endif
 	inline unsigned int SoundOnGPIODuration() const { return soundOnGPIODuration; }
 	inline unsigned int SoundOnGPIOFreq() const { return soundOnGPIOFreq; }
 	inline unsigned int SplitIECLines() const { return splitIECLines; }