diff --git a/bin/debugger.cpp b/bin/debugger.cpp
index 3d68b2b..15b32d1 100644
--- a/bin/debugger.cpp
+++ b/bin/debugger.cpp
@@ -32,7 +32,10 @@
 
 namespace {
 
+	const uint32_t kGlobalSize = 0x10000;
+
 	bool sigInt = false;
+	bool memBreak = false;
 	void sigIntHandler(int)
 	{
 		sigInt = true;
@@ -180,6 +183,8 @@ namespace {
 		// return false to break (toolbreak, address break, etc.)
 
 		uint16_t op;
+		memBreak = false;
+
 		cpuExecuteInstruction();
 
 		uint32_t pc = cpuGetPC();
@@ -205,6 +210,13 @@ namespace {
 			return false; 			
 		}
 
+		if (memBreak)
+		{
+			printf("Memory break\n");
+			memBreak = false;
+			return false;
+		}
+
 
 		// check for pc breaks
 		if (brkMap.lookup(pc))
@@ -250,6 +262,70 @@ namespace {
 	}
 
 
+	void MemoryLogger(uint32_t address, int size, int readWrite, uint32_t value)
+	{
+
+		if (address < kGlobalSize && Flags.traceGlobals)
+		{
+			const char *name = GlobalName(address);
+			if (!name) name = "unknown";
+
+			fprintf(stdout, "%-20s %08x - ", name, address);
+			if (readWrite)
+			{
+				fprintf(stdout, " write %d bytes", size);
+				switch(size)
+				{
+					case 1:
+						fprintf(stdout, " [%02x]\n", value);
+						break;
+					case 2:
+						fprintf(stdout, " [%04x]\n", value);
+						break;
+					case 3:
+						fprintf(stdout, " [%06x]\n", value);
+						break;
+					case 4:
+						fprintf(stdout, " [%08x]\n", value);
+						break;				
+					default:
+						fprintf(stdout, "\n");
+						break;
+				}
+			}
+			else
+			{
+				fprintf(stdout, " read  %d bytes\n", size);
+			}
+		}
+
+
+		// check for memory breaks.
+		if (readWrite)
+		{
+			// todo -- what if writing 1 byte 4-bit address?
+			// todo -- if not single stepping at time of break, should
+			// disasm the prev pc before printing.
+
+
+			if (!wbrkMap.lookup(address)) return;
+
+			printf("Write $%08x\n", address);
+			// todo -- print previous value, old value.
+
+			memBreak = true;
+		}
+		else
+		{
+			if (!rbrkMap.lookup(address)) return;
+
+			printf("Read $%08x\n", address);
+
+			memBreak = true;
+		}
+	}
+
+
 
 }
 
@@ -564,7 +640,40 @@ void Break()
 }
 
 
+void ReadBreak()
+{}
 
+void WriteBreak()
+{}
+
+
+
+void ReadWriteBreak()
+{
+}
+
+
+
+void ReadBreak(int32_t address)
+{
+	// sanity check address?
+
+	if (address < 0) rbrkMap.remove(-address);
+	else rbrkMap.add(address);
+}
+
+void WriteBreak(int32_t address)
+{
+	// sanity check address?
+	if (address < 0) wbrkMap.remove(-address);
+	else wbrkMap.add(address);
+}
+
+void ReadWriteBreak(int32_t address)
+{
+	ReadBreak(address);
+	WriteBreak(address);
+}
 
 void Step(const Command &cmd)
 {
@@ -680,6 +789,7 @@ void Shell()
 	disasm(cpuGetPC());
 
 	signal(SIGINT, sigIntHandler);
+	memorySetLoggingFunc(MemoryLogger);
 
 	for(;;)
 	{
diff --git a/bin/debugger.h b/bin/debugger.h
index ec0ce9f..06852bc 100644
--- a/bin/debugger.h
+++ b/bin/debugger.h
@@ -58,6 +58,15 @@ void ToolBreak();
 void Break(int32_t address);
 void Break();
 
+void ReadBreak();
+void ReadBreak(int32_t address);
+
+void WriteBreak();
+void WriteBreak(int32_t address);
+
+void ReadWriteBreak();
+void ReadWriteBreak(int32_t address);
+
 }
 
 #endif
\ No newline at end of file
diff --git a/bin/lexer.re.cpp b/bin/lexer.re.cpp
index bb5b8a6..86760c9 100644
--- a/bin/lexer.re.cpp
+++ b/bin/lexer.re.cpp
@@ -240,6 +240,22 @@ bool ParseLine(const char *iter, Command *command)
 			continue;	
 		}
 
+		'mbrk' | 'mbreak' | 'rwbrk' | 'rwbreak' {
+			Parse(parser, tkRWBREAK, 0, command);
+			continue;
+		}
+
+		'rbrk' | 'rbreak' {
+			Parse(parser, tkRBREAK, 0, command);
+			continue;
+		}
+
+		'wbrk' | 'wbreak' {
+			Parse(parser, tkWBREAK, 0, command);
+			continue;
+		}
+
+
 		'g' | 'go' {
 			Parse(parser, tkCONTINUE, 0, command);
 			continue;
diff --git a/bin/parser.lemon b/bin/parser.lemon
index cc6993c..97a6995 100644
--- a/bin/parser.lemon
+++ b/bin/parser.lemon
@@ -93,6 +93,33 @@ stmt ::= TBREAK expr(a) EOL.
 	Debug::ToolBreak(a);
 }
 
+stmt ::= RBREAK EOL .
+{
+	Debug::ReadBreak();
+}
+
+stmt ::= RBREAK expr(a) EOL.
+{
+	Debug::ReadBreak(a);
+}
+
+stmt ::= WBREAK EOL.
+{
+	Debug::WriteBreak();
+}
+
+stmt ::= WBREAK expr(a) EOL.
+{
+	Debug::WriteBreak(a);
+}
+
+
+stmt ::= RWBREAK expr(a) EOL .
+{
+	Debug::ReadWriteBreak(a);
+}
+
+
 stmt ::= NEXT EOL.
 {
 	command->action = Debug::cmdStep;