diff --git a/README.md b/README.md
index 0cd373c..a2f7a36 100644
--- a/README.md
+++ b/README.md
@@ -78,8 +78,8 @@ RTS
 
 |FF00 ;dev/console Console
 
-|FFF0 [ f3f0 f30b f30a ] ( palette )
-|FFFA .RESET .FRAME .ERROR
+|FFF0 .RESET .FRAME .ERROR
+|FFF8 [ f3f0 f30b f30a ] ( palette )
 ```
 
 ## Emulator
diff --git a/assembler.c b/assembler.c
index de7f2bf..4947932 100644
--- a/assembler.c
+++ b/assembler.c
@@ -295,11 +295,15 @@ pass1(FILE *f)
 			addr += 1;
 		else {
 			switch(w[0]) {
-			case '|': addr = shex(w + 1); break;
+			case '|':
+				if(shex(w + 1) < addr)
+					return error("Memory Overlap", w);
+				addr = shex(w + 1);
+				break;
 			case '<': addr -= shex(w + 1); break;
 			case '>': addr += shex(w + 1); break;
-			case '=': addr += 4; break; /* STR helper */
-			case '~': addr += 4; break; /* LDR helper */
+			case '=': addr += 4; break; /* STR helper (lit addr-hb addr-lb str) */
+			case '~': addr += 4; break; /* LDR helper (lit addr-hb addr-lb ldr) */
 			case ',': addr += 3; break;
 			case '.': addr += (slen(w + 1) == 2 ? 1 : 2); break;
 			case '+': /* signed positive */
@@ -345,12 +349,12 @@ pass2(FILE *f)
 		else if(w[0] == '+' && sihx(w + 1) && slen(w + 1) == 4) pushshort((Sint16)shex(w + 1), 1);
 		else if(w[0] == '-' && sihx(w + 1) && slen(w + 1) == 2) pushbyte((Sint8)(shex(w + 1) * -1), 1);
 		else if(w[0] == '-' && sihx(w + 1) && slen(w + 1) == 4) pushshort((Sint16)(shex(w + 1) * -1), 1);
-		else if(w[0] == '=' && (l = findlabel(w + 1)) && l->len){ pushshort(findlabeladdr(w+1), 1); pushbyte(findopcode(findlabellen(w+1) == 2? "STR2" : "STR"), 0); }
+		else if(w[0] == '=' && (l = findlabel(w + 1)) && l->len){ pushshort(findlabeladdr(w+1), 1); pushbyte(findopcode(findlabellen(w+1) == 2 ? "STR2" : "STR"), 0); }
 		else if(w[0] == '~' && (l = findlabel(w + 1)) && l->len){ pushshort(findlabeladdr(w+1), 1); pushbyte(findopcode(findlabellen(w+1) == 2 ? "LDR2" : "LDR"), 0); }
+		else if(w[0] == '=' && sihx(w + 1)) { pushshort(shex(w + 1), 1); pushbyte(findopcode("STR2"), 0); }
+		else if(w[0] == '~' && sihx(w + 1)) { pushshort(shex(w + 1), 1); pushbyte(findopcode("LDR2"), 0); }
 		else if((l = findlabel(w + 1))) pushshort(findlabeladdr(w+1), w[0] == ',');
-		else {
-			return error("Unknown label in second pass", w);
-		}
+		else return error("Unknown label in second pass", w);
 		/* clang-format on */
 	}
 	return 1;
diff --git a/build.sh b/build.sh
index 6f35a7f..a7b2e56 100755
--- a/build.sh
+++ b/build.sh
@@ -20,5 +20,5 @@ cc -std=c89 -DDEBUG -Wall -Wno-unknown-pragmas -Wpedantic -Wshadow -Wextra -Werr
 # cc uxn.c emulator.c -std=c89 -Os -DNDEBUG -g0 -s -Wall -Wno-unknown-pragmas -L/usr/local/lib -lSDL2 -o bin/emulator
 
 # run
-./bin/assembler examples/dev.ctrl.usm bin/boot.rom
+./bin/assembler examples/dev.mouse.usm bin/boot.rom
 ./bin/emulator bin/boot.rom
diff --git a/emulator.c b/emulator.c
index e50ca38..749a9eb 100644
--- a/emulator.c
+++ b/emulator.c
@@ -65,7 +65,7 @@ SDL_Texture *gTexture;
 Uint32 *pixels;
 
 Screen screen;
-Device *devconsole, *devscreen, *devmouse, *devkey, *devsprite, *devctrl;
+Device *devconsole, *devscreen, *devmouse, *devkey, *devsprite, *devctrl, *devsystem;
 
 #pragma mark - Helpers
 
@@ -368,6 +368,13 @@ sprite_poke(Uint8 *m, Uint16 ptr, Uint8 b0, Uint8 b1)
 	return b1;
 }
 
+Uint8
+system_poke(Uint8 *m, Uint16 ptr, Uint8 b0, Uint8 b1)
+{
+	printf("system_poke\n");
+	return b1;
+}
+
 Uint8
 ppnil(Uint8 *m, Uint16 ptr, Uint8 b0, Uint8 b1)
 {
@@ -384,7 +391,7 @@ start(Uxn *u)
 {
 	int ticknext = 0;
 	evaluxn(u, u->vreset);
-	loadtheme(u->ram.dat + 0xfff0);
+	loadtheme(u->ram.dat + 0xfff8);
 	if(screen.reqdraw)
 		redraw(pixels, u);
 	while(1) {
@@ -435,10 +442,14 @@ main(int argc, char **argv)
 	devkey = portuxn(&u, "key", ppnil, ppnil);
 	devmouse = portuxn(&u, "mouse", ppnil, ppnil);
 
-	u.ram.dat[0xff10] = (HOR * 8 >> 8) & 0xff;
-	u.ram.dat[0xff11] = HOR * 8 & 0xff;
-	u.ram.dat[0xff12] = (VER * 8 >> 8) & 0xff;
-	u.ram.dat[0xff13] = VER * 8 & 0xff;
+	u.devices = 7;
+	devsystem = portuxn(&u, "system", ppnil, system_poke);
+
+	/* Write screen size to dev/screen */
+	u.ram.dat[devscreen->addr + 0] = (HOR * 8 >> 8) & 0xff;
+	u.ram.dat[devscreen->addr + 1] = HOR * 8 & 0xff;
+	u.ram.dat[devscreen->addr + 2] = (VER * 8 >> 8) & 0xff;
+	u.ram.dat[devscreen->addr + 3] = VER * 8 & 0xff;
 
 	start(&u);
 	quit();
diff --git a/examples/dev.console.usm b/examples/dev.console.usm
index cc057b7..819b62d 100644
--- a/examples/dev.console.usm
+++ b/examples/dev.console.usm
@@ -25,5 +25,5 @@ RTS
 
 |FF00 ;dev/console Console
 
-|FFF0 [ f3f0 f30b f30a ] ( palette )
-|FFFA .RESET .FRAME .ERROR
\ No newline at end of file
+|FFF0 .RESET .FRAME .ERROR
+|FFF8 [ f3f0 f30b f30a ] ( palette )
\ No newline at end of file
diff --git a/examples/dev.ctrl.usm b/examples/dev.ctrl.usm
index eca15fe..4fb86f0 100644
--- a/examples/dev.ctrl.usm
+++ b/examples/dev.ctrl.usm
@@ -75,5 +75,5 @@ RTS
 |FF20 ;dev/sprite Sprite
 |FF30 ;dev/ctrl   Controller
 
-|FFF0 [ 0daf 02ff 035f ] ( palette )
-|FFFA .RESET .FRAME .ERROR
+|FFF0 .RESET .FRAME .ERROR
+|FFF8 [ 0daf 02ff 035f ] ( palette )
diff --git a/examples/dev.key.usm b/examples/dev.key.usm
index 67d540c..d055f1c 100644
--- a/examples/dev.key.usm
+++ b/examples/dev.key.usm
@@ -130,5 +130,5 @@ RTS
 |FF20 ;dev/sprite Sprite
 |FF40 ;dev/key    Keyboard
 
-|FFF0 [ f0ff f00f f00f ] ( palette )
-|FFFA .RESET .FRAME .ERROR
+|FFF0 .RESET .FRAME .ERROR
+|FFF8 [ f0ff f00f f00f ] ( palette )
diff --git a/examples/dev.mouse.usm b/examples/dev.mouse.usm
index 878f5a3..4b3e181 100644
--- a/examples/dev.mouse.usm
+++ b/examples/dev.mouse.usm
@@ -4,8 +4,10 @@
 &Sprite { pad 8 x 2 y 2 addr 2 color 1 }
 &Mouse  { x 2 y 2 state 1 chord 1 }
 
+&Label2d { x 2 y 2 color 1 addr 2 }
 &Point2d { x 2 y 2 }
 
+;label Label2d
 ;cat Point2d 
 ;mouse Point2d
 ;pos Point2d
@@ -23,42 +25,37 @@
 
 BRK
 
-|c000 @FRAME
+|0200 @FRAME
 	
-	( clear last cursor )
-	#10 ,clear_icn ~mouse.x ~mouse.y ,draw-sprite JSR
-	( record mouse positions )
-	~dev/mouse.x =mouse.x ~dev/mouse.y =mouse.y
+	,draw-cursor JSR
+
 	( reset timer -> move cat tail )
-	~dev/mouse.state #01 NEQ ,no-click ROT JMP? POP2
+	,no-click ~dev/mouse.state #00 EQU JMP? POP2
 		#50 =timer
 	@no-click
-
 	( detect click )
-	~dev/mouse.state #11 NEQ ,no-click12 ROT JMP? POP2
-		,mouse12_text #0058 #0040 ,draw-label JSR
+	,no-click12 ~dev/mouse.state #11 NEQ JMP? POP2
+		#0058 #0040 #01 ,mouse12_text ,draw-label JSR
 		#10 ,cursor_icn ~mouse.x ~mouse.y ,draw-sprite JSR
 		~color ,mouse12_icn #0048 #0040 ,draw-sprite JSR
 		,end-click JMP
 	@no-click12
-	~dev/mouse.state #01 NEQ ,no-click1 ROT JMP? POP2
-		,mouse1_text #0058 #0040 ,draw-label JSR
+	,no-click1 ~dev/mouse.state #01 NEQ JMP? POP2
+		#0058 #0040 #01 ,mouse1_text ,draw-label JSR
 		#12 ,cursor_icn ~mouse.x ~mouse.y ,draw-sprite JSR
 		~color ,mouse1_icn #0048 #0040 ,draw-sprite JSR
 		,end-click JMP
 	@no-click1
-	~dev/mouse.state #10 NEQ ,no-click2 ROT JMP? POP2
-		,mouse2_text #0058 #0040 ,draw-label JSR
+	,no-click2 ~dev/mouse.state #10 NEQ JMP? POP2
+		#0058 #0040 #01 ,mouse2_text ,draw-label JSR
 		#13 ,cursor_icn ~mouse.x ~mouse.y ,draw-sprite JSR
 		~color ,mouse2_icn #0048 #0040 ,draw-sprite JSR
 		,end-click JMP
 	@no-click2
 	( default )
-	,mouse0_text #0058 #0040 ,draw-label JSR
+	#0058 #0040 #01 ,mouse0_text ,draw-label JSR
 	~color ,mouse0_icn #0048 #0040 ,draw-sprite JSR
-	#11 ,cursor_icn ~mouse.x ~mouse.y ,draw-sprite JSR
 	@end-click
-	
 	( animate )
 	,animate-polycat JSR
 	( update last pos )
@@ -66,6 +63,21 @@ BRK
 
 BRK
 
+@draw-cursor
+
+	~mouse.x ~dev/mouse.x NEQU2
+	~mouse.y ~dev/mouse.y NEQU2
+
+	#0000 EQU2 RTS? ( Return if unchanged )
+
+	( clear last cursor )
+	#10 ,clear_icn ~mouse.x ~mouse.y ,draw-sprite JSR
+	( record mouse positions )
+	~dev/mouse.x =mouse.x ~dev/mouse.y =mouse.y
+	#11 ,cursor_icn ~mouse.x ~mouse.y ,draw-sprite JSR
+
+RTS
+
 @draw-polycat
 
 	( ears )
@@ -117,14 +129,16 @@ RTS
 
 RTS
 
-@draw-label ( text x1 y1 )
-	=pos.y =pos.x
+@draw-label ( x y color addr )
+	
+	( load ) =label.addr =label.color =dev/sprite.y =dev/sprite.x ~label.addr
 	@draw-label-loop
-		( draw ) ~pos.x ~pos.y =dev/sprite.y =dev/sprite.x DUP2 LDR #00 SWP #0008 MUL2 ,font ADD2 =dev/sprite.addr ~color =dev/sprite.color
+		( draw ) DUP2 LDR #00 SWP #0008 MUL2 ,font ADD2 =dev/sprite.addr ~label.color =dev/sprite.color
 		( incr ) #0001 ADD2
-		( incr ) ~pos.x #0008 ADD2 =pos.x
+		( incr ) ~dev/sprite.x #0008 ADD2 =dev/sprite.x
 		DUP2 LDR #00 NEQ ,draw-label-loop ROT JMP? POP2
 	POP2
+
 RTS
 
 @draw-sprite
@@ -211,10 +225,11 @@ RTS
 @mouse2_text   [ mouse _2 ] <1 .00
 @mouse12_text  [ mouse 12 ] <1 .00
 
+|d000 @ERROR BRK 
+
 |FF10 ;dev/screen Screen
 |FF20 ;dev/sprite Sprite
 |FF50 ;dev/mouse  Mouse
 
-|d000 @ERROR BRK 
-|FFF0 [ 0f85 0fd5 0fb5 ] ( palette )
-|FFFA .RESET .FRAME .ERROR
+|FFF0 .RESET .FRAME .ERROR
+|FFF8 [ 0f85 0fd5 0fb5 ] ( palette )
diff --git a/examples/dev.screen.usm b/examples/dev.screen.usm
index e4c0d11..97579ff 100644
--- a/examples/dev.screen.usm
+++ b/examples/dev.screen.usm
@@ -53,5 +53,5 @@ BRK
 |FF10 ;dev/screen Screen
 |FF20 ;dev/sprite Sprite
 
-|FFF0 [ f0ac f0bb f053 ] ( palette )
-|FFFA .RESET .FRAME .ERROR ( vectors )
+|FFF0 .RESET .FRAME .ERROR ( vectors )
+|FFF8 [ f0ac f0bb f053 ] ( palette )
diff --git a/examples/gui.picture.usm b/examples/gui.picture.usm
index a3dc159..f98600f 100644
--- a/examples/gui.picture.usm
+++ b/examples/gui.picture.usm
@@ -312,5 +312,5 @@ RTS
 |FF10 ;dev/screen Screen
 |FF20 ;dev/sprite Sprite
 
-|FFF0 [ 0ffc 0f0b 0f03 ] ( palette )
-|FFFA .RESET .FRAME .ERROR
+|FFF0 .RESET .FRAME .ERROR
+|FFF8 [ 0ffc 0f0b 0f03 ] ( palette )
diff --git a/examples/gui.shapes.usm b/examples/gui.shapes.usm
index a7c94ae..9bb0cf3 100644
--- a/examples/gui.shapes.usm
+++ b/examples/gui.shapes.usm
@@ -149,5 +149,5 @@ RTS
 |FF10 ;dev/screen Screen
 |FF20 ;dev/sprite Sprite
 
-|FFF0 [ 0f0f 0fff 0ff0 ] ( palette )
-|FFFA .RESET .FRAME .ERROR ( vectors )
\ No newline at end of file
+|FFF0 .RESET .FRAME .ERROR ( vectors )
+|FFF8 [ 0f0f 0fff 0ff0 ] ( palette )
\ No newline at end of file
diff --git a/examples/old.hover.usm b/examples/old.hover.usm
index 2c741bb..ed2ff20 100644
--- a/examples/old.hover.usm
+++ b/examples/old.hover.usm
@@ -180,5 +180,5 @@ RTS
 
 |d000 @ERROR BRK 
 
-|FFF0 [ e2af eab2 e652 ] ( palette )
-|FFFA .RESET .FRAME .ERROR
+|FFF0 .RESET .FRAME .ERROR
+|FFF8 [ e2af eab2 e652 ] ( palette )
diff --git a/examples/old.paint.usm b/examples/old.paint.usm
index 66eeb64..e531edb 100644
--- a/examples/old.paint.usm
+++ b/examples/old.paint.usm
@@ -91,5 +91,5 @@ BRK
 
 |d000 @ERROR BRK 
 
-|FFF0 [ f1c3 f12e f12a ] ( palette )
-|FFFA .RESET .FRAME .ERROR
+|FFF0 .RESET .FRAME .ERROR
+|FFF8 [ f1c3 f12e f12a ] ( palette )
diff --git a/uxn.c b/uxn.c
index 6c77ba0..99cd20c 100644
--- a/uxn.c
+++ b/uxn.c
@@ -193,9 +193,9 @@ loaduxn(Uxn *u, char *filepath)
 	if(!(f = fopen(filepath, "rb")))
 		return haltuxn(u, "Missing input rom.", 0);
 	fread(u->ram.dat, sizeof(u->ram.dat), 1, f);
-	u->vreset = mempeek16(u, 0xfffa);
-	u->vframe = mempeek16(u, 0xfffc);
-	u->verror = mempeek16(u, 0xfffe);
+	u->vreset = mempeek16(u, 0xfff0);
+	u->vframe = mempeek16(u, 0xfff2);
+	u->verror = mempeek16(u, 0xfff4);
 	printf("Uxn loaded[%s] vrst:%04x vfrm:%04x verr:%04x.\n",
 		filepath,
 		u->vreset,