diff --git a/stack.cpp b/stack.cpp
index 91cf184..c70293d 100644
--- a/stack.cpp
+++ b/stack.cpp
@@ -16,20 +16,20 @@ const bool stack_isfull(t_stack& stack) {
 	return stack.top == stack.max;
 }
 
-void stack_push(t_stack& stack, const char value) {
+void stack_push(t_stack& stack, const unsigned char value) {
 	if (!stack_isfull(stack)) {
 		stack.data[++stack.top] = value;
 	}
 }
 
-const char stack_pop(t_stack& stack) {
+const unsigned char stack_pop(t_stack& stack) {
 	if (!stack_isempty(stack)) {
 		return stack.data[stack.top--];
 	}
 
 }
 
-const char stack_peek(t_stack& stack) {
+const unsigned char stack_peek(t_stack& stack) {
 	return stack.data[stack.top];
 }
 
diff --git a/stack.h b/stack.h
index f2e2a87..42c84a1 100644
--- a/stack.h
+++ b/stack.h
@@ -6,10 +6,10 @@ struct t_stack {
 	int max{ 0 };
 };
 
-void		stack_init(t_stack& stack, const int size);
-const bool	stack_isempty(t_stack& stack);
-const bool	stack_isfull(t_stack& stack);
-void		stack_push(t_stack& stack, const char value);
-const char	stack_pop(t_stack& stack);
-const char	stack_peek(t_stack& stack);
-void		stack_delete(t_stack& stack);
+void				stack_init(t_stack& stack, const int size);
+const bool			stack_isempty(t_stack& stack);
+const bool			stack_isfull(t_stack& stack);
+void				stack_push(t_stack& stack, const unsigned char value);
+const unsigned char	stack_pop(t_stack& stack);
+const unsigned char	stack_peek(t_stack& stack);
+void				stack_delete(t_stack& stack);
diff --git a/vm.cpp b/vm.cpp
index 0a5bd21..488b181 100644
--- a/vm.cpp
+++ b/vm.cpp
@@ -4,6 +4,9 @@
 #define MAX_DATA_STACK		256
 #define MAX_CALL_STACK		256
 
+typedef unsigned char byte;
+typedef unsigned short word;
+
 enum OPS {
 	OP_NOP = 0,
 	OP_PUSH,
@@ -21,6 +24,8 @@ enum OPS {
 	OP_SETX,
 	OP_SETY,
 	OP_SETZ,
+	OP_GETY,
+	OP_GETZ,
 	OP_INCX,
 	OP_DECX,
 	OP_INCY,
@@ -62,6 +67,7 @@ enum OPS {
 	OP_NEG,
 	OP_INC,
 	OP_DEC,
+	OP_CONCAT,
 
 	OP_EQ,
 	OP_NEQ,
@@ -69,12 +75,20 @@ enum OPS {
 	OP_GT,
 	OP_LEQ,
 	OP_GEQ,
+
+	OP_IN,
+	OP_OUT,
 };
 
 typedef void(*t_extcall)(t_stack&);
 t_extcall external_calls[MAX_EXTERNAL_CALLS];
 int numcallbacks = 0;
-	
+
+typedef void(*t_out_port)(const byte&);
+typedef byte(*t_in_port)();
+t_out_port out_ports[256];
+t_in_port in_ports[256];
+
 const unsigned char* vm_program = nullptr;
 int vm_pc = 0;
 int vm_cycles = 0;
@@ -112,6 +126,8 @@ void vm_step() {
 	case OP_SETX: rX = WORD(); vm_cycles++; break;
 	case OP_SETY: rY = stack_pop(vm_datastack); vm_cycles++; break;
 	case OP_SETZ: rZ = stack_pop(vm_datastack); vm_cycles++; break;
+	case OP_GETY: stack_push(vm_datastack, rY); vm_cycles++; break;
+	case OP_GETZ: stack_push(vm_datastack, rZ); vm_cycles++; break;
 	case OP_INCX: rX++; vm_cycles++; break;
 	case OP_DECX: rX--; vm_cycles++; break;
 	case OP_INCY: rY++; vm_cycles++; break;
@@ -125,19 +141,19 @@ void vm_step() {
 	case OP_RET: rZ = stack_pop(vm_callstack); rY = stack_pop(vm_callstack); rX = (stack_pop(vm_callstack) << 8) + stack_pop(vm_callstack); vm_pc = stack_pop(vm_callstack); vm_cycles++; break;
 	case OP_CALL: external_calls[vm_program[vm_pc++]](vm_datastack); vm_cycles++; break;
 	case OP_RJ: vm_pc += vm_program[vm_pc]; vm_cycles++; break;
-	case OP_RB: vm_pc -= vm_program[vm_pc]; vm_cycles++; break;
+	case OP_RB: vm_pc -= vm_program[vm_pc]+1; vm_cycles++; break;
 	case OP_RJZ: if (stack_pop(vm_datastack) == 0) vm_pc += vm_program[vm_pc]; vm_cycles++; break;
 	case OP_RJN: if (stack_pop(vm_datastack) != 0) vm_pc += vm_program[vm_pc]; vm_cycles++; break;
-	case OP_RBZ: if (stack_pop(vm_datastack) == 0) vm_pc -= vm_program[vm_pc]; vm_cycles++; break;
-	case OP_RBN: if (stack_pop(vm_datastack) != 0) vm_pc -= vm_program[vm_pc]; vm_cycles++; break;
+	case OP_RBZ: if (stack_pop(vm_datastack) == 0) vm_pc -= vm_program[vm_pc]+1; vm_cycles++; break;
+	case OP_RBN: if (stack_pop(vm_datastack) != 0) vm_pc -= vm_program[vm_pc]+1; vm_cycles++; break;
 	case OP_RJYZ: if (rY == 0) vm_pc += vm_program[vm_pc]; vm_cycles++; break;
 	case OP_RJYN: if (rY != 0) vm_pc += vm_program[vm_pc]; vm_cycles++; break;
-	case OP_RBYZ: if (rY == 0) vm_pc -= vm_program[vm_pc]; vm_cycles++; break;
-	case OP_RBYN: if (rY != 0) vm_pc -= vm_program[vm_pc]; vm_cycles++; break;
+	case OP_RBYZ: if (rY == 0) vm_pc -= vm_program[vm_pc]+1; vm_cycles++; break;
+	case OP_RBYN: if (rY != 0) vm_pc -= vm_program[vm_pc]+1; vm_cycles++; break;
 	case OP_RJZZ: if (rZ == 0) vm_pc += vm_program[vm_pc]; vm_cycles++; break;
 	case OP_RJZN: if (rZ != 0) vm_pc += vm_program[vm_pc]; vm_cycles++; break;
-	case OP_RBZZ: if (rZ == 0) vm_pc -= vm_program[vm_pc]; vm_cycles++; break;
-	case OP_RBZN: if (rZ != 0) vm_pc -= vm_program[vm_pc]; vm_cycles++; break;
+	case OP_RBZZ: if (rZ == 0) vm_pc -= vm_program[vm_pc]+1; vm_cycles++; break;
+	case OP_RBZN: if (rZ != 0) vm_pc -= vm_program[vm_pc]+1; vm_cycles++; break;
 	case OP_ADD: stack_push(vm_datastack, stack_pop(vm_datastack) + stack_pop(vm_datastack)); vm_cycles++; break;
 	case OP_SUB: stack_push(vm_datastack, stack_pop(vm_datastack) - stack_pop(vm_datastack)); vm_cycles++; break;
 	case OP_MUL: stack_push(vm_datastack, stack_pop(vm_datastack) * stack_pop(vm_datastack)); vm_cycles++; break;
@@ -149,15 +165,32 @@ void vm_step() {
 	case OP_NEG: stack_push(vm_datastack, -stack_pop(vm_datastack)); vm_cycles++; break;
 	case OP_INC: stack_push(vm_datastack, stack_pop(vm_datastack)+1); vm_cycles++; break;
 	case OP_DEC: stack_push(vm_datastack, stack_pop(vm_datastack) - 1); vm_cycles++; break;
+	case OP_CONCAT:
+		val = stack_pop(vm_datastack);
+		for (int i = 0; i < val; i++) stack_push(vm_callstack, stack_pop(vm_datastack));
+		val2 = stack_pop(vm_datastack);
+		for (int i = 0; i < val; i++) stack_push(vm_datastack, stack_pop(vm_callstack));
+		stack_push(vm_datastack, val + val2);
+		vm_cycles++; break;
 	case OP_EQ: stack_push(vm_datastack, stack_pop(vm_datastack) == stack_pop(vm_datastack)); vm_cycles++; break;
 	case OP_NEQ: stack_push(vm_datastack, stack_pop(vm_datastack) != stack_pop(vm_datastack)); vm_cycles++; break;
 	case OP_LT: stack_push(vm_datastack, stack_pop(vm_datastack) < stack_pop(vm_datastack)); vm_cycles++; break;
 	case OP_GT: stack_push(vm_datastack, stack_pop(vm_datastack) > stack_pop(vm_datastack)); vm_cycles++; break;
 	case OP_LEQ: stack_push(vm_datastack, stack_pop(vm_datastack) <= stack_pop(vm_datastack)); vm_cycles++; break;
 	case OP_GEQ: stack_push(vm_datastack, stack_pop(vm_datastack) >= stack_pop(vm_datastack)); vm_cycles++; break;
+	case OP_IN: stack_push(vm_datastack, in_ports[vm_program[vm_pc++]]()); vm_cycles++; break;
+	case OP_OUT: out_ports[vm_program[vm_pc++]](stack_pop(vm_datastack)); vm_cycles++; break;
 	}
 }
 
 void vm_register_call(void(*callback)(t_stack&)) {
 	external_calls[numcallbacks++] = callback;
 }
+
+void vm_register_in_port(const byte port, t_in_port callback) {
+	in_ports[port] = callback;
+}
+
+void vm_register_out_port(const byte port, t_out_port callback) {
+	out_ports[port] = callback;
+}
diff --git a/vm.h b/vm.h
index adc7ff6..d402517 100644
--- a/vm.h
+++ b/vm.h
@@ -4,3 +4,5 @@
 void vm_init(const unsigned char* program);
 void vm_step();
 void vm_register_call(void(*callback)(t_stack&));
+void vm_register_in_port(const unsigned char port, unsigned char(*callback)(void));
+void vm_register_out_port(const unsigned char port, void(*callback)(const unsigned char&));