( screen ) :dev/r fff8 ( std read port ) :dev/w fff9 ( std write port ) ;width 2 ;height 2 |0100 @RESET ( set read/write to dev/screen ) ,01 DUP ,dev/r STR ,dev/w STR ( load screen size ) ,00 IOR2 ,width STR2 ,02 IOR2 ,height STR2 ( draw pixel at screen center ) ,0101 ,width LDR2 ,0002 DIV2 ,height LDR2 ,0002 DIV2 ,putpixel JSR BRK |c000 @FRAME BRK @putpixel IOW2 ( y short ) IOW2 ( x short ) IOW ( color byte ) IOW ( redraw byte ) RTS |d000 @ERROR BRK |FFFA .RESET .FRAME .ERROR