diff --git a/main.usm b/main.usm
index 8132044..a654706 100644
--- a/main.usm
+++ b/main.usm
@@ -41,6 +41,7 @@
 		&pattern-x $2 &pattern-y $2 
 		&pattern-vspacing $2 &pattern-hspacing $2
 		&playhead-x $2 &playhead-y $2 ]
+@Edit [ &selection-x $1 &selection-y $1 ]
 
 ( program )
 
@@ -48,13 +49,13 @@
 
 ( set a pallete )
 #0f00 .System/r DEO2 
-#0ff0 .System/g DEO2
-#0f0f .System/b DEO2
+#0f00 .System/g DEO2
+#0fff .System/b DEO2
 
 ( speed - how many ticks we play a note every )
-#10 .Playback/speed POK
+#10 .Playback/speed STZ
 
-;pattern .Playback/pattern-addr POK2
+;pattern .Playback/pattern-addr STZ2
 
 ( display/audio init )
 ;on-frame .Screen/vector DEO2
@@ -63,27 +64,34 @@
 #0002 .Audio0/length DEO2
 
 ( drawing properties )
-#0010 .Draw/pattern-x POK2
-#0010 .Draw/pattern-y POK2
-#0004 .Draw/pattern-vspacing POK2
-#0007 .Draw/playhead-x POK2
-#0004 .Draw/pattern-hspacing POK2
+#0010 .Draw/pattern-x STZ2
+#0010 .Draw/pattern-y STZ2
+#0004 .Draw/pattern-vspacing STZ2
+#0007 .Draw/playhead-x STZ2
+#0004 .Draw/pattern-hspacing STZ2
 BRK
 
 @on-frame ( -> )
 	;draw JSR2
-	.Playback/tick PEK .Playback/speed PEK NEQ ,&inc JNZ ( if the tick != speed, skip to inc )
+	.Playback/tick LDZ .Playback/speed LDZ NEQ ,&inc JCN ( if the tick != speed, skip to inc )
 	;on-step JSR2 ( otherwise, run the on-step routine )
-	#00 .Playback/tick POK ( reset the tick )
+	#00 .Playback/tick STZ ( reset the tick )
 	,&end JMP ( jump to end )
 	&inc
-	#01 .Playback/tick PEK ADD .Playback/tick POK ( tick up 1 )
+	#01 .Playback/tick LDZ ADD .Playback/tick STZ ( tick up 1 )
 	&end
 BRK
 
 @draw-nibble ( nibble ) 
 	#08 MUL #00 SWP ;font_hex ADD2 .Screen/addr DEO2 ( locate nibble in the hex font )
+	.Edit/selection-y LDZ .Draw/row LDZ NEQ 
+	.Edit/selection-x LDZ .Draw/col LDZ NEQ ADD ( if the row and column are the selected ones, use a different color )
+	,&else JCN
+	#22 .Screen/color DEO
+	,&then JMP
+	&else
 	#21 .Screen/color DEO ( display it )
+	&then
 	.Screen/x DEI2 #0008 ADD2 .Screen/x DEO2 ( move right a sprite )
 RTN
 	
@@ -95,36 +103,36 @@ RTN
 
 ( draw-pattern-line draws a single line in a pattern )
 @draw-pattern-line ( addr )
-	#00 .Draw/col POK
+	#00 .Draw/col STZ
 	&loop
 		DUP2 LDA ;draw-byte JSR2
 		.Screen/x DEI2 #0004 ADD2 .Screen/x DEO2 ( add spacing between digits )
 		#0001 ADD2 ( get the next byte in the pattern )
-		#01 .Draw/col PEK ADD .Draw/col POK
-		.Draw/col PEK PTN_WIDTH LOB NEQ ,&loop JNZ
+		#01 .Draw/col LDZ ADD .Draw/col STZ
+		.Draw/col LDZ PTN_WIDTH LOB NEQ ,&loop JCN
 	POP2 ( remove final address from stack )
 RTN
 
 ( draw-pattern draws a pattern )
 @draw-pattern ( addr )
-	#00 .Draw/row POK
+	#00 .Draw/row STZ
 	&loop
-		.Draw/pattern-y PEK2 .Screen/x DEO2
+		.Draw/pattern-y LDZ2 .Screen/x DEO2
 		DUP2 ;draw-pattern-line JSR2
-		.Screen/y DEI2 #0008 .Draw/pattern-vspacing PEK2 ADD2 ADD2 .Screen/y DEO2 ( add spacing between rows )
+		.Screen/y DEI2 #0008 .Draw/pattern-vspacing LDZ2 ADD2 ADD2 .Screen/y DEO2 ( add spacing between rows )
 		PTN_WIDTH ADD2 ( get the next byte in the pattern )
-		#01 .Draw/row PEK ADD .Draw/row POK
-		.Draw/row PEK PTN_LEN LOB NEQ ,&loop JNZ
+		#01 .Draw/row LDZ ADD .Draw/row STZ
+		.Draw/row LDZ PTN_LEN LOB NEQ ,&loop JCN
 	POP2 ( remove final address from stack )
 RTN
 
 @draw-playhead 
 	( clear previous playhead )
-	.Draw/playhead-y PEK2 .Screen/y DEO2
-	.Draw/playhead-x PEK2 .Screen/x DEO2
+	.Draw/playhead-y LDZ2 .Screen/y DEO2
+	.Draw/playhead-x LDZ2 .Screen/x DEO2
 	#20 .Screen/color DEO
 	( draw new playhead )
-	.Draw/pattern-y PEK2 .Playback/position PEK2 #0001 SUB2 #0004 MUL2 ADD2 #0008 SUB2  DUP2 .Draw/playhead-y POK2
+	.Draw/pattern-y LDZ2 .Playback/position LDZ2 #0001 SUB2 #0004 MUL2 ADD2 #0008 SUB2  DUP2 .Draw/playhead-y STZ2
 	.Screen/y DEO2
 	;playhead_icon .Screen/addr DEO2
 	#21 .Screen/color DEO
@@ -132,26 +140,26 @@ RTN
 
 @draw
 	;draw-playhead JSR2
-	.Draw/pattern-x PEK2 .Screen/x DEO2
-	.Draw/pattern-y PEK2 .Screen/y DEO2
-	.Playback/pattern-addr PEK2 ;draw-pattern JSR2
+	.Draw/pattern-x LDZ2 .Screen/x DEO2
+	.Draw/pattern-y LDZ2 .Screen/y DEO2
+	.Playback/pattern-addr LDZ2 ;draw-pattern JSR2
 RTN
 	
 @on-step ( whenever a pattern step should be played )
 
-	PTN_WIDTH PTN_LEN MUL2 .Playback/position PEK2 NEQ2 ,&continue JNZ ( if we're at the end of the pattern, reset the counter )
-	#0000 .Playback/position POK2
+	PTN_WIDTH PTN_LEN MUL2 .Playback/position LDZ2 NEQ2 ,&continue JCN ( if we're at the end of the pattern, reset the counter )
+	#0000 .Playback/position STZ2
 	&continue
-	.Playback/position PEK2 .Playback/pattern-addr PEK2 ADD2 ( put pattern line address on the stack )
+	.Playback/position LDZ2 .Playback/pattern-addr LDZ2 ADD2 ( put pattern line address on the stack )
 	DUP2 VOL LDA .Audio0/volume DEO ( ln -- ) ( put the address of the pattern line on the stack )
 	NOTE LDA  ( get the current note )
-	DUP #00 EQU ,&rest JNZ ( if the note is 00, aka empty, skip playing it )
+	DUP #00 EQU ,&rest JCN ( if the note is 00, aka empty, skip playing it )
 	.Audio0/pitch DEO ( play the note )
 	,&end JMP ( jump to the end )
 	
 	&rest POP ( if the note is a 00, jump here. POP to clean up the stack )
 	&end
-	PTN_WIDTH .Playback/position PEK2 ADD2 .Playback/position POK2
+	PTN_WIDTH .Playback/position LDZ2 ADD2 .Playback/position STZ2
 	;draw-playhead JSR2 ( update the playhead position )
 RTN