diff --git a/sources/APU/DSP/DSP.hpp b/sources/APU/DSP/DSP.hpp
index 3ae3fd0..6de6b07 100644
--- a/sources/APU/DSP/DSP.hpp
+++ b/sources/APU/DSP/DSP.hpp
@@ -48,10 +48,14 @@ namespace ComSquare::APU::DSP
 		uint8_t data;
 		//! @brief Offset position after data start
 		uint16_t offset;
+		//! @brief offset maximum
+		uint16_t length;
 		//! @brief Echo delay size register (EDL)
 		uint8_t delay;
 		//! @brief Echo enabled (5th bit FLG)
 		bool enabled = true;
+		//! @brief Application of enabled to channels.
+		bool toggle;
 		//! @brief Last sound produced for each voice in each channel
 		std::array<std::array<int16_t, 8>, 2> history;
 		//! @brief Current position inside history
@@ -417,6 +421,7 @@ namespace ComSquare::APU::DSP
 		int32_t loadFIR(bool channel, int fir);
 		void loadEcho(bool channel);
 		int16_t outputEcho(bool channel);
+		void writeEcho(bool channel);
 
 		void timerTick();
 		bool timerPoll(uint32_t rate);
diff --git a/sources/APU/DSP/Echo.cpp b/sources/APU/DSP/Echo.cpp
index 51823c4..d11a444 100644
--- a/sources/APU/DSP/Echo.cpp
+++ b/sources/APU/DSP/Echo.cpp
@@ -23,6 +23,18 @@ namespace ComSquare::APU::DSP
 		this->_echo.history[channel][this->_echo.historyOffset] = echo >> 1;
 	}
 
+	void DSP::writeEcho(bool channel)
+	{
+		if (!this->_echo.toggle) {
+			uint16_t address = this->_echo.address + channel * 2;
+			int16_t sample = this->_echo.output[channel];
+
+			this->_writeRAM(address++, sample);
+			this->_writeRAM(address, sample >> 8);
+		}
+		this->_echo.output[channel] = 0;
+	}
+
 	int16_t DSP::outputEcho(bool channel)
 	{
 		int16_t master = this->_master.output[channel] * this->_master.volume[channel] >> 7;
@@ -93,36 +105,65 @@ namespace ComSquare::APU::DSP
 
 	void DSP::echo28()
 	{
-
+		this->_echo.toggle = this->_echo.enabled;
 	}
 
 	void DSP::echo29()
 	{
+		this->_echo.value = this->_echo.data;
 
+		if (!this->_echo.offset)
+			this->_echo.length = this->_echo.delay << 11;
+
+		this->_echo.offset += 4;
+		if (this->_echo.offset >= this->_echo.length)
+			this->_echo.offset = 0;
+
+		this->writeEcho(0);
+
+		echo28();
 	}
 
 	void DSP::echo30()
 	{
-
+		this->writeEcho(1);
 	}
 
 	void DSP::misc27()
 	{
-
+		for (int i = 0; i < 8; i++)
+			this->_voices[i].prevPmon = this->_voices[i].pmon;
 	}
 
 	void DSP::misc28()
 	{
-
+		for (int i = 0; i < 8; i++)
+			this->_voices[i].tempNon = this->_voices[i].non;
+		this->_brr.offsetAddr = this->_brr.offset;
 	}
 
 	void DSP::misc29()
 	{
-
+		this->_timer.sample = !this->_timer.sample;
+		if (this->_timer.sample) {
+			for (int i = 0; i < 8; i++)
+				this->_voices[i].kon = 0;
+		}
 	}
 
 	void DSP::misc30()
 	{
+		if (this->_timer.sample) {
+			for (int i = 0; i < 8; i++)
+				this->_voices[i].kof = 0;
+		}
 
+		this->timerTick();
+
+		if (!this->timerPoll(this->_noise.clock))
+			return;
+		int32_t feedback = this->_noise.lfsr << 13 ^ this->_noise.lfsr << 14;
+
+		this->_noise.lfsr = feedback & 0x4000 ^ this->_noise.lfsr >> 1;
 	}
 }
\ No newline at end of file