diff --git a/cpu.c b/cpu.c
index 3af8e53..0c200b6 100644
--- a/cpu.c
+++ b/cpu.c
@@ -11,10 +11,10 @@ void free_fetch_data(__attribute__((unused)) struct fetch_data_t *tofree){
 }
 int fetch(struct simdata_t *simdata){
 	free_instr_list(&simdata->cpu_gui_hints->fetching_list);
-	simdata->decode_data->in_bytecode=(uint32_t)(simdata->RAM[simdata->PC])<<24|(uint32_t)(simdata->RAM[simdata->PC+1])<<16|(uint32_t)(simdata->RAM[simdata->PC+2])<<8|(uint32_t)(simdata->RAM[simdata->PC+3]);
-	simdata->decode_data->address=simdata->PC;
-	add_to_instr_list(&simdata->cpu_gui_hints->fetching_list,simdata->PC);
-	simdata->PC+=4;
+	simdata->decode_data->in_bytecode=(uint32_t)(simdata->RAM[simdata->registers->PC])<<24|(uint32_t)(simdata->RAM[simdata->registers->PC+1])<<16|(uint32_t)(simdata->RAM[simdata->registers->PC+2])<<8|(uint32_t)(simdata->RAM[simdata->registers->PC+3]);
+	simdata->decode_data->address=simdata->registers->PC;
+	add_to_instr_list(&simdata->cpu_gui_hints->fetching_list,simdata->registers->PC);
+	simdata->registers->PC+=4;
 	return 0;
 }
 
@@ -200,18 +200,18 @@ int exec(struct simdata_t *simdata){
 			}
 			if(condition){
 				if(simdata->exec_data->EXEC_ACTION==CALL){
-					simdata->RAM[simdata->SP]=simdata->PC;
-					simdata->SP+=6;
+					simdata->RAM[simdata->registers->SP]=simdata->registers->PC;
+					simdata->registers->SP+=6;
 				}
 				if(simdata->exec_data->out_op->OP_ADDR==IMMEDIATE)
-					simdata->PC=simdata->exec_data->out_op->data;
+					simdata->registers->PC=simdata->exec_data->out_op->data;
 				else
 					return 1;
 			}
 			break;
 		case RET:
-			simdata->SP-=6;
-			simdata->PC=simdata->RAM[simdata->SP];
+			simdata->registers->SP-=6;
+			simdata->registers->PC=simdata->RAM[simdata->registers->SP];
 			break;
 		case EXEC_ALU:
 			if(	simdata->exec_data->in_op1->OP_ADDR==REGISTER &&
@@ -273,12 +273,12 @@ int exec(struct simdata_t *simdata){
 				case REGISTER: /* This is for special registers like the SP which is 24bits long */
 					if(simdata->exec_data->in_op1->OP_ADDR==IMMEDIATE){
 						if( (simdata->exec_data->in_op1->data&0xFF000000) == 0 )
-							simdata->SP=simdata->exec_data->in_op1->data;
+							simdata->registers->SP=simdata->exec_data->in_op1->data;
 						else
 							return 2;
 					}else{
 						if( (simdata->registers->GPR[simdata->exec_data->in_op1->data]&0xFF000000) == 0 )
-							simdata->SP=simdata->registers->GPR[simdata->exec_data->in_op1->data];
+							simdata->registers->SP=simdata->registers->GPR[simdata->exec_data->in_op1->data];
 						else
 							return 2;
 					}
@@ -349,6 +349,8 @@ int cpu_simdata_malloc(struct simdata_t *simdata){
 	simdata->decode_data=malloc_decode_data();
 	simdata->exec_data=malloc_exec_data();
 	simdata->registers=malloc(sizeof(struct registers_t));
+	simdata->registers->PC=0x00000000;
+	simdata->registers->SP&=0x00FFFFFF; //intentionally leave it uninitialised but within the legal range
 	if((simdata->fetch_data!=NULL)&&(simdata->decode_data!=NULL)&&(simdata->exec_data!=NULL))
 		return 1;
 	else
diff --git a/cpu.h b/cpu.h
index e231db2..ccde7fc 100644
--- a/cpu.h
+++ b/cpu.h
@@ -79,6 +79,8 @@ int cpu_cycle_clock(struct simdata_t *simdata);
 struct registers_t{
 	uint32_t GPR[8];
 	uint32_t FLAGS;
+	uint32_t PC;
+	uint32_t SP;
 };
 
 #endif
diff --git a/gui.c b/gui.c
index c6cb63a..207a444 100644
--- a/gui.c
+++ b/gui.c
@@ -243,6 +243,11 @@ int update_general_disas(struct simdata_t *simdata){
 	int width,height;
 	getmaxyx(general_disas,height,width);
 	box(general_disas, 0 , 0);
+	mvwprintw(general_disas,0,width/2-7,"[ DISASSEMBLY ]");
+	if(simdata->registers==NULL||simdata->RAM==NULL){
+		mvwprintw(general_disas,1,1,"Data not initialised");
+		return 0;
+	}
 	int offset_arrow;
 
 	int have_legend=(width>29);
@@ -253,17 +258,16 @@ int update_general_disas(struct simdata_t *simdata){
 		offset_arrow=2;
 	else
 		offset_arrow=3;
-	mvwprintw(general_disas,0,width/2-7,"[ DISASSEMBLY ]");
 	if(width<18){
 		mvwprintw(general_disas,1,1,"too small window");
 	}else{
-		uint32_t ADDRESS=(simdata->PC-(usable_height/2-2)*4)&0x00FFFFFF;
+		uint32_t ADDRESS=(simdata->registers->PC-(usable_height/2-2)*4)&0x00FFFFFF;
 		for (int i=2;i<usable_height;i++){
 			int overall_offset=offset_arrow-2;
 
 			mvwaddch(general_disas,i,11+overall_offset,ACS_VLINE);
 
-			if(ADDRESS==simdata->PC)
+			if(ADDRESS==simdata->registers->PC)
 				wattron(general_disas,A_BOLD);
 			mvwprintw(general_disas,i,4+overall_offset,"%06X",ADDRESS);
 			char* disas=disassemble(*(uint32_t*)(simdata->RAM+ADDRESS));
@@ -275,7 +279,7 @@ int update_general_disas(struct simdata_t *simdata){
 			mvwprintw(general_disas,i,13+overall_offset,"%s",disas);
 			select_instruction_color(simdata,general_disas,ADDRESS,0);
 
-			if(ADDRESS==simdata->PC)
+			if(ADDRESS==simdata->registers->PC)
 				wattroff(general_disas,A_BOLD);
 
 			ADDRESS=(ADDRESS+4)&0xFFFFFF;
@@ -319,6 +323,10 @@ int update_general_stack(struct simdata_t *simdata){
 	getmaxyx(general_stack,height,width);
 	box(general_stack, 0 , 0);
 	mvwprintw(general_stack,0,width/2-4,"[ STACK ]");
+	if(simdata->registers==NULL||simdata->RAM==NULL){
+		mvwprintw(general_stack,1,1,"Data not initialised");
+		return 0;
+	}
 	if(width<13){
 		mvwprintw(general_stack,1,1,"too small window");
 	}else{
@@ -333,13 +341,13 @@ int update_general_stack(struct simdata_t *simdata){
 		}
 
 		// draw data
-		uint32_t ADDRESS=(simdata->SP-(height/2-2)*4)&0x00FFFFFF;
+		uint32_t ADDRESS=(simdata->registers->SP-(height/2-2)*4)&0x00FFFFFF;
 
 		for(int i=0;i<height-4;i++){
-			if(ADDRESS==simdata->SP)
+			if(ADDRESS==simdata->registers->SP)
 				wattron(general_stack,A_BOLD);
 			mvwprintw(general_stack,i+2,offset_data,"%08X",*(uint32_t*)(simdata->RAM+ADDRESS));
-			if(ADDRESS==simdata->SP)
+			if(ADDRESS==simdata->registers->SP)
 				wattroff(general_stack,A_BOLD);
 			ADDRESS=(ADDRESS+4)&0xFFFFFF;
 		}
@@ -375,13 +383,17 @@ int update_general_memdump(struct simdata_t *simdata){
 	getmaxyx(general_memdump,height,width);
 	box(general_memdump, 0 , 0);
 	mvwprintw(general_memdump,0,terminal_width/4-6,"[ MEMDUMP ]");
+	if(simdata->registers==NULL||simdata->RAM==NULL){
+		mvwprintw(general_memdump,1,1,"Data not initialised");
+		return 0;
+	}
 	if(width<16){
 		mvwprintw(general_memdump,1,1,"too small window");
 	}else{
 		int n=(width-12)/4; // bytes in each line
 		int usable_height=height-3-(width-12)%2;
 
-		uint32_t ADDRESS=(simdata->PC-n*usable_height/2)&0x00FFFFFF;
+		uint32_t ADDRESS=(simdata->registers->PC-n*usable_height/2)&0x00FFFFFF;
 
 		uint32_t color_addr;
 		int have_color;
@@ -391,7 +403,7 @@ int update_general_memdump(struct simdata_t *simdata){
 			wprintw(general_memdump,"%06x  ",ADDRESS);
 			uint32_t temp_address=ADDRESS;
 			for (int i=0;i<n;i++){
-				if(ADDRESS>=simdata->PC&&ADDRESS<=simdata->PC+3)
+				if(ADDRESS>=simdata->registers->PC&&ADDRESS<=simdata->registers->PC+3)
 					wattron(general_memdump,A_BOLD);
 				else
 					wattroff(general_memdump,A_BOLD);
@@ -412,7 +424,7 @@ int update_general_memdump(struct simdata_t *simdata){
 				select_instruction_color(simdata,general_memdump,color_addr,0);
 			ADDRESS=temp_address;
 			for (int i=0;i<n;i++){
-				if(ADDRESS>=simdata->PC&&ADDRESS<=simdata->PC+3)
+				if(ADDRESS>=simdata->registers->PC&&ADDRESS<=simdata->registers->PC+3)
 					wattron(general_memdump,A_BOLD);
 				else
 					wattroff(general_memdump,A_BOLD);
@@ -430,6 +442,10 @@ int update_general_registers(struct simdata_t *simdata){
 	getmaxyx(general_registers,height,width);
 	box(general_registers, 0 , 0);
 	mvwprintw(general_registers,0,terminal_width/4-7,"[ REGISTERS ]");
+	if(simdata->registers==NULL){
+		mvwprintw(general_registers,1,1,"Data not initialised");
+		return 0;
+	}
 	if(simdata->registers==NULL)
 		mvwprintw(general_registers,1,1,"Registers data structure not initialised");
 	else{
diff --git a/simdata.c b/simdata.c
index 6218187..dad352d 100644
--- a/simdata.c
+++ b/simdata.c
@@ -36,8 +36,6 @@ struct simdata_t *init_simdata(){
 		return 0;
 	}
 
-	ret->PC=0;
-	ret->SP=0;
 	ret->registers=NULL;
 	ret->cpu_state=CPU_RUNNING;
 	ret->cpu_gui_hints=malloc(sizeof(struct cpu_gui_hints_t));
diff --git a/simdata.h b/simdata.h
index c83f6b3..8999d5f 100644
--- a/simdata.h
+++ b/simdata.h
@@ -9,8 +9,6 @@ enum CPU_STATE_t{
 struct simdata_t{
 	long unsigned int current_clock;
 	uint8_t *RAM;
-	uint32_t PC;
-	uint32_t SP;
 	struct fetch_data_t *fetch_data;
 	struct decode_data_t *decode_data;
 	struct exec_data_t *exec_data;