diff --git a/fpga/icebreaker_vga.dg b/fpga/icebreaker_vga.dg
index 376f010..bcfa6a9 100644
--- a/fpga/icebreaker_vga.dg
+++ b/fpga/icebreaker_vga.dg
@@ -40,10 +40,14 @@ run_icepll = current target ->
 
 
 Top = subclass Elaboratable where
+    __init__ = x y ~> None where
+        @x = x
+        @y = y
+
     elaborate = platform ~> m where with m = Module! =>
 
         # Configure DVI controller
-        dvi = Submodule$ DviController12 x:800 y:480 fps:60
+        dvi = Submodule$ DviController12 @x @y fps:60
 
         # setup clock
 
@@ -94,13 +98,13 @@ Top = subclass Elaboratable where
         Sync$ dvi.r :== 0x0
         Sync$ dvi.g :== 0x0
         Sync$ dvi.b :== 0x0
-        cx = to_signed dvi.pixel_x - (800//2)
-        cy = to_signed dvi.pixel_y - (480//2)
+        cx = to_signed dvi.pixel_x - (@x // 2)
+        cy = to_signed dvi.pixel_y - (@y // 2)
         rx = cx*cx
         ry = cy*cy
-        tx1 = (dvi.pixel_x - scroll) & (1<<5)
-        ty1 = (dvi.pixel_y - scroll) & (1<<5)
-        tx2 = (dvi.pixel_x + scroll) & (1<<6)
+        tx1 = (dvi.pixel_x - scroll     ) & (1<<5)
+        ty1 = (dvi.pixel_y - scroll     ) & (1<<5)
+        tx2 = (dvi.pixel_x + scroll     ) & (1<<6)
         ty2 = (dvi.pixel_y + scroll + 40) & (1<<6)
         When
             rx + ry < 200**2 ,->
@@ -118,4 +122,4 @@ if __name__ == "__main__" =>
     plat = ICEBreakerPlatform!
     plat.add_resources$ pmod.dvi_12bit 0
     plat.add_resources$ plat.break_off_pmod
-    plat.build Top! do_program: ("--flash" in sys.argv) synth_opts: "-dsp"
+    plat.build (Top 800 480) do_program: ("--flash" in sys.argv) synth_opts: "-dsp"