diff --git a/BizHawk.Emulation/CPUs/CP1610/Execute.cs b/BizHawk.Emulation/CPUs/CP1610/Execute.cs
index e499bcaf1e..b7cee1e7c3 100644
--- a/BizHawk.Emulation/CPUs/CP1610/Execute.cs
+++ b/BizHawk.Emulation/CPUs/CP1610/Execute.cs
@@ -8,6 +8,8 @@ namespace BizHawk.Emulation.CPUs.CP1610
 {
 	public sealed partial class CP1610
 	{
+		private const string HLT_UNEXPECTED = "HLT is an unexpected behavior.";
+
 		private void Calc_FlagC(int result)
 		{
 			FlagC = ((result & 0x10000) != 0);
@@ -53,8 +55,7 @@ namespace BizHawk.Emulation.CPUs.CP1610
 				switch (opcode)
 				{
 					case 0x000: // HLT
-						// Unexpected behavior.
-						throw new ArgumentException();
+						throw new ArgumentException(HLT_UNEXPECTED);
 					case 0x001: // SDBD
 						FlagD = true;
 						PendingCycles -= 4; TotalExecutedCycles += 4;
@@ -1015,7 +1016,7 @@ namespace BizHawk.Emulation.CPUs.CP1610
 						ext = opcode & 0x10;
 						// BEXT
 						if (ext != 0)
-							throw new NotImplementedException();
+							throw new NotImplementedException("BEXT not implemented.");
 						else
 						{
 							switch (cond)
diff --git a/BizHawk.Emulation/Consoles/Intellivision/MemoryMap.cs b/BizHawk.Emulation/Consoles/Intellivision/MemoryMap.cs
index 01314ca4e2..db545233f5 100644
--- a/BizHawk.Emulation/Consoles/Intellivision/MemoryMap.cs
+++ b/BizHawk.Emulation/Consoles/Intellivision/MemoryMap.cs
@@ -7,13 +7,27 @@ namespace BizHawk.Emulation.Consoles.Intellivision
 {
 	public sealed partial class Intellivision
 	{
+		private const string INVALID = "Invalid memory address.";
+		private const string UNOCCUPIED = "Unoccupied memory address.";
+		private const string UNOCCUPIED_CART_READ = "Unoccupied memory address available to cartridge not mapped as"
+			+ " readable.";
+		private const string UNOCCUPIED_CART_WRITE = "Unoccupied memory address available to cartridge not mapped as"
+			+ " writable.";
+		private const string READ_ONLY_STIC = "This STIC Register alias is read-only.";
+		private const string READ_ONLY_EXEC = "Executive ROM is read-only.";
+		private const string READ_ONLY_GROM = "Graphics ROM is read-only.";
+		private const string WRITE_ONLY_STIC = "This STIC Register alias is write-only.";
+		private const string GARBAGE = "Memory address contains a garbage value, perhaps only in the Intellivision II.";
+		private const string INTV2_EXEC = "Additional EXEC ROM, Intellivision II only.";
+
 		private ushort[] STIC_Registers = new ushort[64];
 		private ushort[] Scratchpad_RAM = new ushort[240];
 		private ushort[] PSG_Registers = new ushort[16];
 		private ushort[] System_RAM = new ushort[352];
-		private ushort[] Executive_ROM = new ushort[4096];
+		private ushort[] Executive_ROM = new ushort[4096]; // TODO: Intellivision II support?
 		private ushort[] Graphics_ROM = new ushort[2048];
 		private ushort[] Graphics_RAM = new ushort[512];
+		private ushort[] Cartridge = new ushort[23552]; // TODO: Resize as cartridge mapping grows.
 
 		public ushort ReadMemory(ushort addr)
 		{
@@ -22,28 +36,203 @@ namespace BizHawk.Emulation.Consoles.Intellivision
 			switch (addr & 0xF000)
 			{
 				case 0x0000:
-					if (addr >= 0x0100 && addr <= 0x01EF)
+					if (addr <= 0x003F)
+						// TODO: OK only during VBlank Period 1.
+						core = STIC_Registers[addr];
+					else if (addr <= 0x007F)
+						// TODO: OK only during VBlank Period 2.
+						core = STIC_Registers[addr & 0x003F];
+					else if (addr <= 0x00FF)
+						throw new ArgumentException(UNOCCUPIED);
+					else if (addr <= 0x01EF)
 						core = Scratchpad_RAM[addr & 0x00EF];
-					else if (addr >= 0x01F0 && addr <= 0x01FF)
+					else if (addr <= 0x01FF)
 						core = PSG_Registers[addr & 0x000F];
-					else if (addr >= 0x0200 && addr <= 0x035F)
+					else if (addr <= 0x035F)
 						core = System_RAM[addr & 0x015F];
+					else if (addr <= 0x03FF)
+						// TODO: Intellivision II support?
+						throw new ArgumentException(GARBAGE);
+					else if (addr <= 0x04FF)
+						// TODO: Actually map cartridge (on all but Intellivision II) RAM / ROM to decide which path to take.
+						if (false)
+							// TODO: Intellivision II support?
+							throw new ArgumentException(INTV2_EXEC);
+						else
+							core = Cartridge[addr & 0x00FF];
+					else if (addr <= 0x06FF)
+						// TODO: Actually map cartridge RAM / ROM to decide which path to take.
+						if (false)
+							throw new ArgumentException(UNOCCUPIED_CART_READ);
+						else
+							core = Cartridge[addr & 0x02FF];
+					else if (addr <= 0x0CFF)
+						// TODO: Actually map cartridge (only if no Intellivoice) RAM / ROM to decide which path to take.
+						if (false)
+							throw new ArgumentException(UNOCCUPIED_CART_READ);
+						else
+							core = Cartridge[addr & 0x08FF];
 					else
-						throw new NotImplementedException();
+						// TODO: Actually map cartridge RAM / ROM to decide which path to take.
+						if (false)
+							throw new ArgumentException(UNOCCUPIED_CART_READ);
+						else
+							core = Cartridge[addr & 0x0BFF];
 					break;
 				case 0x1000:
 					core = Executive_ROM[addr & 0x0FFF];
 					break;
+				case 0x2000:
+					// TODO: Actually map cartridge (only if no ECS) RAM / ROM to decide which path to take.
+					if (false)
+						throw new ArgumentException(UNOCCUPIED_CART_READ);
+					else
+						core = Cartridge[(addr & 0x0FFF) + 0x0C00];
+					break;
 				case 0x3000:
-					if (addr >= 0x3000 && addr <= 0x37FF)
+					if (addr <= 0x37FF)
+						// TODO: OK only during VBlank Period 2.
 						core = Graphics_ROM[addr & 0x07FF];
-					else if (addr >= 0x3800 && addr <= 0x39FF)
+					else if (addr <= 0x39FF)
+						// TODO: OK only during VBlank Period 2.
+						core = Graphics_RAM[addr & 0x01FF];
+					else if (addr <= 0x3BFF)
+						// TODO: OK only during VBlank Period 2.
+						core = Graphics_RAM[addr & 0x01FF];
+					else if (addr <= 0x3DFF)
+						// TODO: OK only during VBlank Period 2.
 						core = Graphics_RAM[addr & 0x01FF];
 					else
-						throw new NotImplementedException();
+						// TODO: OK only during VBlank Period 2.
+						core = Graphics_RAM[addr & 0x01FF];
+					break;
+				case 0x4000:
+					if (addr <= 0x403F)
+					{
+						// TODO: Actually map cartridge (only if no ECS) RAM / ROM to decide which path to take.
+						if (true)
+						{
+							// TODO: OK only during VBlank Period 1.
+							if (addr == 0x4021)
+								// TODO: Switch into Color Stack mode.
+								core = STIC_Registers[0x0021];
+							else
+								throw new ArgumentException(WRITE_ONLY_STIC);
+						}
+						else
+							core = Cartridge[(addr & 0x003F) + 0x1C00];
+					}
+					else if (addr <= 0x47FF)
+					{
+						// TODO: Actually map cartridge (only if no ECS) RAM / ROM to decide which path to take.
+						if (false)
+							throw new ArgumentException(UNOCCUPIED_CART_READ);
+						else
+							core = Cartridge[(addr & 0x07FF) + 0x1C00];
+					}
+					else if (addr == 0x4800)
+					{
+						// TODO: Actually map cartridge RAM / ROM to decide which path to take.
+						if (false)
+							throw new ArgumentException(UNOCCUPIED_CART_READ);
+						else
+							core = Cartridge[0x2400];
+					}
+					else
+					{
+						// TODO: Actually map cartridge RAM / ROM to decide which path to take.
+						if (false)
+							throw new ArgumentException(UNOCCUPIED_CART_READ);
+						else
+							core = Cartridge[(addr & 0x0FFF) + 0x01C00];
+					}
+					break;
+				case 0x5000:
+				case 0x6000:
+					if (addr <= 0x5014)
+					{
+						// TODO: Actually map cartridge RAM / ROM to decide which path to take.
+						if (false)
+							throw new ArgumentException(UNOCCUPIED_CART_READ);
+						else
+							core = Cartridge[(addr & 0x0014) + 0x02C00];
+					}
+					else
+					{
+						// TODO: Actually map cartridge RAM / ROM to decide which path to take.
+						if (false)
+							throw new ArgumentException(UNOCCUPIED_CART_READ);
+						else
+							core = Cartridge[(addr & 0x1FFF) + 0x02C00];
+					}
+					break;
+				case 0x7000:
+					if (addr == 0x7000)
+					{
+						/*
+						 TODO: Actually map cartridge (only if no ECS) RAM (confuses EXEC boot sequence) / ROM to decide
+						 which path to take.
+						*/
+						if (false)
+							throw new ArgumentException(UNOCCUPIED_CART_READ);
+						else
+							core = Cartridge[0x04C00];
+					}
+					else if (addr <= 0x77FF)
+					{
+						// TODO: Actually map cartridge (only if no ECS) RAM / ROM to decide which path to take.
+						if (false)
+							throw new ArgumentException(UNOCCUPIED_CART_READ);
+						else
+							core = Cartridge[(addr & 0x07FF) + 0x04C00];
+					}
+					else if (addr <= 0x79FF)
+					{
+						/*
+						 TODO: Actually map cartridge (only if no ECS) RAM (Do not because of GRAM alias) / ROM to decide
+						 which path to take.
+						*/
+						if (false)
+							throw new ArgumentException(UNOCCUPIED_CART_READ);
+						else
+							core = Cartridge[(addr & 0x09FF) + 0x04C00];
+					}
+					else if (addr <= 0x7BFF)
+					{
+						/*
+						 TODO: Actually map cartridge (only if no ECS) RAM (Do not because of GRAM alias) / ROM to decide
+						 which path to take.
+						*/
+						if (false)
+							throw new ArgumentException(UNOCCUPIED_CART_READ);
+						else
+							core = Cartridge[(addr & 0x0BFF) + 0x04C00];
+					}
+					else if (addr <= 0x7DFF)
+					{
+						/*
+						 TODO: Actually map cartridge (only if no ECS) RAM (Do not because of GRAM alias) / ROM to decide
+						 which path to take.
+						*/
+						if (false)
+							throw new ArgumentException(UNOCCUPIED_CART_READ);
+						else
+							core = Cartridge[(addr & 0x0DFF) + 0x04C00];
+					}
+					else
+					{
+						/*
+						 TODO: Actually map cartridge (only if no ECS) RAM (Do not because of GRAM alias) / ROM to decide
+						 which path to take.
+						*/
+						if (false)
+							throw new ArgumentException(UNOCCUPIED_CART_READ);
+						else
+							core = Cartridge[(addr & 0x0FFF) + 0x04C00];
+					}
 					break;
 				default:
-					throw new NotImplementedException();
+					throw new ArgumentException(INVALID);
 			}
 			/*
 			TODO: Fix Intellicart hook.
@@ -59,33 +248,195 @@ namespace BizHawk.Emulation.Consoles.Intellivision
 			switch (addr & 0xF000)
 			{
 				case 0x0000:
-					if (addr >= 0x0100 && addr <= 0x01EF)
-					{
+					if (addr <= 0x003F)
+						STIC_Registers[addr] = value;
+					else if (addr <= 0x007F)
+						throw new ArgumentException(READ_ONLY_STIC);
+					else if (addr <= 0x00FF)
+						throw new ArgumentException(UNOCCUPIED);
+					else if (addr <= 0x01EF)
 						Scratchpad_RAM[addr & 0x00EF] = value;
-						break;
-					}
-					else if (addr >= 0x01F0 && addr <= 0x01FF)
-					{
+					else if (addr <= 0x01FF)
 						PSG_Registers[addr & 0x000F] = value;
-						break;
-					}
-					else if (addr >= 0x0200 && addr <= 0x035F)
-					{
+					else if (addr <= 0x035F)
 						System_RAM[addr & 0x015F] = value;
-						break;
-					}
+					else if (addr <= 0x03FF)
+						// TODO: Intellivision II support?
+						throw new ArgumentException(GARBAGE);
+					else if (addr <= 0x04FF)
+						// TODO: Actually map cartridge (on all but Intellivision II) RAM / ROM to decide which path to take.
+						if (false)
+							// TODO: Intellivision II support?
+							throw new ArgumentException(INTV2_EXEC);
+						else
+							Cartridge[addr & 0x00FF] = value;
+					else if (addr <= 0x06FF)
+						// TODO: Actually map cartridge RAM / ROM to decide which path to take.
+						if (false)
+							throw new ArgumentException(UNOCCUPIED_CART_WRITE);
+						else
+							Cartridge[addr & 0x02FF] = value;
+					else if (addr <= 0x0CFF)
+						// TODO: Actually map cartridge (only if no Intellivoice) RAM / ROM to decide which path to take.
+						if (false)
+							throw new ArgumentException(UNOCCUPIED_CART_WRITE);
+						else
+							Cartridge[addr & 0x08FF] = value;
 					else
-						throw new NotImplementedException();
+						// TODO: Actually map cartridge RAM / ROM to decide which path to take.
+						if (false)
+							throw new ArgumentException(UNOCCUPIED_CART_WRITE);
+						else
+							Cartridge[addr & 0x0BFF] = value;
+					break;
+				case 0x1000:
+					throw new ArgumentException(READ_ONLY_EXEC);
+				case 0x2000:
+					// TODO: Actually map cartridge (only if no ECS) RAM / ROM to decide which path to take.
+					if (false)
+						throw new ArgumentException(UNOCCUPIED_CART_WRITE);
+					else
+						Cartridge[(addr & 0x0FFF) + 0x0C00] = value;
+					break;
 				case 0x3000:
-					if (addr >= 0x3800 && addr <= 0x39FF)
-					{
+					if (addr <= 0x37FF)
+						throw new ArgumentException(READ_ONLY_GROM);
+					else if (addr <= 0x39FF)
+						// TODO: OK only during VBlank Period 2.
 						Graphics_RAM[addr & 0x01FF] = value;
-						break;
+					else if (addr <= 0x3BFF)
+						// TODO: OK only during VBlank Period 2.
+						Graphics_RAM[addr & 0x01FF] = value;
+					else if (addr <= 0x3DFF)
+						// TODO: OK only during VBlank Period 2.
+						Graphics_RAM[addr & 0x01FF] = value;
+					else
+						// TODO: OK only during VBlank Period 2.
+						Graphics_RAM[addr & 0x01FF] = value;
+					break;
+				case 0x4000:
+					if (addr <= 0x403F)
+					{
+						// TODO: Actually map cartridge (only if no ECS) RAM / ROM to decide which path to take.
+						if (true)
+							// TODO: OK only during VBlank Period 1.
+							STIC_Registers[addr & 0x003F] = value;
+						else
+							Cartridge[(addr & 0x003F) + 0x1C00] = value;
+					}
+					else if (addr <= 0x47FF)
+					{
+						// TODO: Actually map cartridge (only if no ECS) RAM / ROM to decide which path to take.
+						if (false)
+							throw new ArgumentException(UNOCCUPIED_CART_WRITE);
+						else
+							Cartridge[(addr & 0x07FF) + 0x1C00] = value;
+					}
+					else if (addr == 0x4800)
+					{
+						// TODO: Actually map cartridge (only if boot ROM at $7000) RAM / ROM to decide which path to take.
+						if (false)
+							throw new ArgumentException(UNOCCUPIED_CART_WRITE);
+						else
+							Cartridge[0x2400] = value;
 					}
 					else
-						throw new NotImplementedException();
+					{
+						// TODO: Actually map cartridge RAM / ROM to decide which path to take.
+						if (false)
+							throw new ArgumentException(UNOCCUPIED_CART_WRITE);
+						else
+							Cartridge[(addr & 0x0FFF) + 0x01C00] = value;
+					}
+					break;
+				case 0x5000:
+				case 0x6000:
+					if (addr <= 0x5014)
+					{
+						/*
+						 TODO: Actually map (only if boot ROM at $4800 or $7000) cartridge RAM / ROM to decide which path to
+						 take.
+						*/
+						if (false)
+							throw new ArgumentException(UNOCCUPIED_CART_WRITE);
+						else
+							Cartridge[(addr & 0x0014) + 0x02C00] = value;
+					}
+					else
+					{
+						if (false)
+							throw new ArgumentException(UNOCCUPIED_CART_WRITE);
+						else
+							Cartridge[(addr & 0x1FFF) + 0x02C00] = value;
+					}
+					break;
+				case 0x7000:
+					if (addr == 0x7000)
+					{
+						/*
+						 TODO: Actually map cartridge (only if no ECS) RAM (confuses EXEC boot sequence) / ROM to decide
+						 which path to take.
+						*/
+						if (false)
+							throw new ArgumentException(UNOCCUPIED_CART_WRITE);
+						else
+							Cartridge[0x04C00] = value;
+					}
+					else if (addr <= 0x77FF)
+					{
+						// TODO: Actually map cartridge (only if no ECS) RAM / ROM to decide which path to take.
+						if (false)
+							throw new ArgumentException(UNOCCUPIED_CART_WRITE);
+						else
+							Cartridge[(addr & 0x07FF) + 0x04C00] = value;
+					}
+					else if (addr <= 0x79FF)
+					{
+						/*
+						 TODO: Actually map cartridge (only if no ECS) RAM (Do not because of GRAM alias) / ROM to decide
+						 which path to take.
+						*/
+						if (true)
+							Graphics_RAM[addr & 0x01FF] = value;
+						else
+							Cartridge[(addr & 0x09FF) + 0x04C00] = value;
+					}
+					else if (addr <= 0x7BFF)
+					{
+						/*
+						 TODO: Actually map cartridge (only if no ECS) RAM (Do not because of GRAM alias) / ROM to decide
+						 which path to take.
+						*/
+						if (true)
+							Graphics_RAM[addr & 0x01FF] = value;
+						else
+							Cartridge[(addr & 0x0BFF) + 0x04C00] = value;
+					}
+					else if (addr <= 0x7DFF)
+					{
+						/*
+						 TODO: Actually map cartridge (only if no ECS) RAM (Do not because of GRAM alias) / ROM to decide
+						 which path to take.
+						*/
+						if (true)
+							Graphics_RAM[addr & 0x01FF] = value;
+						else
+							Cartridge[(addr & 0x0DFF) + 0x04C00] = value;
+					}
+					else
+					{
+						/*
+						 TODO: Actually map cartridge (only if no ECS) RAM (Do not because of GRAM alias) / ROM to decide
+						 which path to take.
+						*/
+						if (true)
+							Graphics_RAM[addr & 0x01FF] = value;
+						else
+							Cartridge[(addr & 0x0FFF) + 0x04C00] = value;
+					}
+					break;
 				default:
-					throw new NotImplementedException();
+					throw new ArgumentException(INVALID);
 			}
 		}
 	}