diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9766372..5ab3a26 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -52,7 +52,7 @@ add_executable(unit_tests
         sources/CPU/Instructions/CommonInstructions.hpp
         sources/Exceptions/InvalidOpcode.hpp
         sources/CPU/Instructions/Interrupts.cpp
-        sources/CPU/Instructions/MathematicalOperations.cpp tests/CPU/Math/testADC.cpp)
+        sources/CPU/Instructions/MathematicalOperations.cpp tests/CPU/Math/testADC.cpp tests/CPU/testStore.cpp)
 
 # include criterion & coverage
 target_link_libraries(unit_tests criterion -lgcov)
diff --git a/sources/CPU/CPU.cpp b/sources/CPU/CPU.cpp
index aeeefa0..40246b7 100644
--- a/sources/CPU/CPU.cpp
+++ b/sources/CPU/CPU.cpp
@@ -441,4 +441,15 @@ namespace ComSquare::CPU
 		base += this->_registers.dbr << 16u;
 		return base + this->_registers.y;
 	}
+
+	unsigned CPU::STA(uint24_t addr)
+	{
+		if (this->_registers.p.m)
+			this->_bus->write(addr, this->_registers.al);
+		else {
+			this->_bus->write(addr, this->_registers.al);
+			this->_bus->write(addr + 1, this->_registers.ah);
+		}
+		return 0;
+	}
 }
\ No newline at end of file
diff --git a/sources/CPU/CPU.hpp b/sources/CPU/CPU.hpp
index 960dbae..f74a8bf 100644
--- a/sources/CPU/CPU.hpp
+++ b/sources/CPU/CPU.hpp
@@ -288,6 +288,8 @@ namespace ComSquare::CPU
 		//! @brief Add with carry - Adds operand to the Accumulator; adds an additional 1 if carry is set.
 		//! @return The number of extra cycles that this operation took.
 		unsigned ADC(uint24_t valueAddr);
+		//! @brief Store the accumulator to memory.
+		unsigned STA(uint24_t addr);
 	public:
 		explicit CPU(std::shared_ptr<Memory::MemoryBus> bus, Cartridge::Header &cartridgeHeader);
 		//! @brief This function continue to execute the Cartridge code.
diff --git a/sources/Exceptions/InvalidAction.hpp b/sources/Exceptions/InvalidAction.hpp
index a7827ea..8b9c06a 100644
--- a/sources/Exceptions/InvalidAction.hpp
+++ b/sources/Exceptions/InvalidAction.hpp
@@ -11,7 +11,7 @@
 namespace ComSquare
 {
 	//! @brief Exception thrown when someone tries to load an invalid rom.
-	class InvalidAction : std::exception {
+	class InvalidAction : public std::exception {
 	private:
 		std::string _msg;
 	public:
diff --git a/sources/Exceptions/InvalidAddress.hpp b/sources/Exceptions/InvalidAddress.hpp
index beb3d8c..09724ae 100644
--- a/sources/Exceptions/InvalidAddress.hpp
+++ b/sources/Exceptions/InvalidAddress.hpp
@@ -13,7 +13,7 @@
 namespace ComSquare
 {
 	//! @brief Exception thrown when trying to read/write to an invalid address.
-	class InvalidAddress : std::exception {
+	class InvalidAddress : public std::exception {
 	private:
 		std::string _msg;
 	public:
@@ -25,6 +25,24 @@ namespace ComSquare
 		}
 		const char *what() const noexcept override { return this->_msg.c_str(); }
 	};
+
+	//! @brief Exception thrown when trying to read/write to an invalid address in a rectangle memory region.
+	class InvalidRectangleAddress : public std::exception {
+	private:
+		std::string _msg;
+	public:
+		InvalidRectangleAddress(std::string where, int32_t addr, int16_t subaddr, int16_t start, int16_t end)
+		{
+			std::stringstream stream;
+			stream << "Could not read/write data at address: 0x" << std::hex << addr << " from " << where;
+			if (subaddr < start)
+				stream << " (" << std::hex << subaddr << " < " << start << ")";
+			else
+				stream << " (" << std::hex << subaddr << " > " << end << ")";
+			this->_msg = stream.str();
+		}
+		const char *what() const noexcept override { return this->_msg.c_str(); }
+	};
 }
 
 #endif //COMSQUARE_INVALIDADDRESS_HPP
diff --git a/sources/Exceptions/InvalidRom.hpp b/sources/Exceptions/InvalidRom.hpp
index acbf0b3..433c478 100644
--- a/sources/Exceptions/InvalidRom.hpp
+++ b/sources/Exceptions/InvalidRom.hpp
@@ -11,7 +11,7 @@
 namespace ComSquare
 {
 	//! @brief Exception thrown when someone tries to load an invalid rom.
-	class InvalidRomException : std::exception {
+	class InvalidRomException : public std::exception {
 	private:
 		std::string _msg;
 	public:
diff --git a/sources/Exceptions/NotImplementedException.hpp b/sources/Exceptions/NotImplementedException.hpp
index 762c655..8aba3e6 100644
--- a/sources/Exceptions/NotImplementedException.hpp
+++ b/sources/Exceptions/NotImplementedException.hpp
@@ -10,7 +10,7 @@
 namespace ComSquare
 {
 	//! @brief When this is thrown, it means that we should work more.
-	class NotImplementedException : std::exception {
+	class NotImplementedException : public std::exception {
 	public:
 		explicit NotImplementedException() = default;
 		const char *what() const noexcept override { return "Not implemented yet."; }
diff --git a/sources/Memory/IRectangleMemory.cpp b/sources/Memory/IRectangleMemory.cpp
index df5e7ef..9340572 100644
--- a/sources/Memory/IRectangleMemory.cpp
+++ b/sources/Memory/IRectangleMemory.cpp
@@ -31,10 +31,10 @@ namespace ComSquare::Memory
 		unsigned bankCount = bank - this->_startBank;
 		unsigned pageCount = this->_endPage - this->_startPage;
 
-		if (bank < this->_startBank || bank >= this->_endBank)
-			throw InvalidAddress("Rectangle memory write Invalid Bank", addr);
-		if (page < this->_startPage || page >= this->_endPage)
-			throw InvalidAddress("Rectangle memory write Invalid Page", addr);
+		if (bank < this->_startBank || bank > this->_endBank)
+			throw InvalidRectangleAddress("Rectangle memory write Invalid Bank", addr, bank, this->_startBank, this->_endBank);
+		if (page < this->_startPage || page > this->_endPage)
+			throw InvalidRectangleAddress("Rectangle memory write Invalid Page", addr, page, this->_startPage, this->_endPage);
 		page -= this->_startPage;
 		page += pageCount * bankCount;
 		this->write_internal(page, data);
diff --git a/tests/CPU/testAddressingMode.cpp b/tests/CPU/testAddressingMode.cpp
index e52b695..3d09508 100644
--- a/tests/CPU/testAddressingMode.cpp
+++ b/tests/CPU/testAddressingMode.cpp
@@ -20,6 +20,8 @@ Test(AddrMode, Immediate)
 {
 	auto pair = Init();
 	pair.second.cpu->_registers.pac = 0x000015;
+	pair.second.cpu->_isEmulationMode = true;
+	pair.second.cpu->_registers.p.m = false;
 	cr_assert_eq(pair.second.cpu->_getImmediateAddr(), 0x000015, "Got %x, Expected 0x000015");
 	cr_assert_eq(pair.second.cpu->_registers.pac, 0x000016);
 }
@@ -27,6 +29,7 @@ Test(AddrMode, Immediate)
 Test(AddrMode, ImmediateMemoryFlag)
 {
 	auto pair = Init();
+	pair.second.cpu->_isEmulationMode = true;
 	pair.second.cpu->_registers.pac = 0x000015;
 	pair.second.cpu->_registers.p.m = true;
 	cr_assert_eq(pair.second.cpu->_getImmediateAddr(), 0x000015, "Got %x, Expected 0x000015");
@@ -37,6 +40,7 @@ Test(AddrMode, ImmediateBankChange)
 {
 	auto pair = Init();
 	pair.second.cpu->_registers.pac = 0x00FFFF;
+	pair.second.cpu->_registers.p.m = false;
 	cr_assert_eq(pair.second.cpu->_getImmediateAddr(), 0x00FFFF);
 	cr_assert_eq(pair.second.cpu->_registers.pac, 0x010000);
 }
diff --git a/tests/CPU/testStore.cpp b/tests/CPU/testStore.cpp
new file mode 100644
index 0000000..914ecfc
--- /dev/null
+++ b/tests/CPU/testStore.cpp
@@ -0,0 +1,20 @@
+//
+// Created by anonymus-raccoon on 2/12/20.
+//
+
+#include <criterion/criterion.h>
+#include <iostream>
+#include <bitset>
+#include "../tests.hpp"
+#include "../../sources/SNES.hpp"
+using namespace ComSquare;
+//
+//Test(STA, 8bits)
+//{
+//	auto pair = Init();
+//	pair.second.cpu->_registers.p.m = false;
+//	pair.second.cpu->_registers.a = 0x11;
+//	pair.second.cpu->STA(0x0);
+//	auto data = pair.second.wram->_data[0];
+//	cr_assert_eq(data, 0x11, "The stored value should be 0x11 but it was 0x%x.", data);
+//}
\ No newline at end of file
diff --git a/tests/testMemoryBus.cpp b/tests/testMemoryBus.cpp
index ed9488d..b79ca1e 100644
--- a/tests/testMemoryBus.cpp
+++ b/tests/testMemoryBus.cpp
@@ -261,12 +261,31 @@ Test(BusAccessor, GetRomMirror3)
 	cr_assert_eq(accessor->_initial.get(), pair.second.cartridge.get());
 }
 
+Test(BusAccessor, Get0x0)
+{
+	auto pair = Init();
+	std::shared_ptr<Memory::RectangleShadow> accessor = nullptr;
+
+	accessor = std::static_pointer_cast<Memory::RectangleShadow>(pair.first->getAccessor(0x0));
+	cr_assert_eq(accessor->_initial.get(), pair.second.wram.get());
+}
+
 ///////////////////////////
 //						 //
 // MemoryBus::read tests //
 //						 //
 ///////////////////////////
 
+Test(BusRead, Read0x0)
+{
+	auto pair = Init();
+	uint8_t data;
+
+	pair.second.wram->_data[0] = 123;
+	data = pair.first->read(0x0);
+	cr_assert_eq(data, 123);
+}
+
 Test(BusRead, ReadOutside, .init = cr_redirect_stdout)
 {
 	auto pair = Init();
@@ -394,6 +413,19 @@ Test(BusRead, ReadWRAMMirror)
 //						  //
 ////////////////////////////
 
+Test(BusWrite, Write0x0)
+{
+	auto pair = Init();
+
+	try {
+		pair.first->write(0x0, 123);
+	} catch (std::exception &ex) {
+		std::cout << ex.what() << std::endl;
+	}
+	cr_assert_eq(pair.second.wram->_data[0], 123);
+}
+
+
 Test(BusWrite, WriteAPU)
 {
 	auto pair = Init();