( screen )

:dev/r fff8 ( std read port )
:dev/w fff9 ( std write port )

;centerx 2 ;centery 2 ;i 2

|0100 @RESET 
	
	( set read/write to dev/screen )
	#01 DUP =dev/r =dev/w 

	( find screen center )
	#00 IOR2 #0002 DIV2 =centerx
	#02 IOR2 #0002 DIV2 =centery

	( draw hor line )
	#0000 =i
	@draw-hor
		#03 ~i ~centery ,draw-pixel JSR
		~i #0002 ADD2 =i ( increment )
	~i #00 IOR2 LTH2 ,draw-hor ROT JMP? POP2

	( draw ver line )
	#0000 =i
	@draw-ver
		#03 ~centerx ~i ,draw-pixel JSR
		~i #0002 ADD2 =i ( increment )
	~i #02 IOR2 LTH2 ,draw-ver ROT JMP? POP2

	( draw pixel in the middle )
	#01 ~centerx ~centery ,draw-pixel JSR

BRK

@draw-pixel 
	IOW2 ( y short )
	IOW2 ( x short )
	IOW ( color byte )
	RTS

|c000 @FRAME BRK
|d000 @ERROR BRK 
|FFF0 [ f0ac f0bb f053 ] ( palette )
|FFFA .RESET .FRAME .ERROR ( vectors )