dim LineColor = a NextFrame VerticalSync ; Grouping these together saves cycles WSYNC = 2 : VSYNC = 2 : WSYNC = 2 : WSYNC = 2 WSYNC = 0 : VSYNC = 0 VerticalBlank ; Set timer for VB TIM64T = 44 ; Your vertical blank code ; Wait for VB timer to expire before visible screen WaitVB if INTIM then goto WaitVB VisibleScreen VBLANK = 0 ; Draw a different color on each scanline for temp5 = 0 to 191 WSYNC = 0 COLUBK = LineColor LineColor = LineColor + 2 next WSYNC = 0 : LineColor = 0 : COLUBK = 0 OverScan ; Set timer for OS TIM64T = 36 WSYNC = 2 : VBLANK = 2 ; Your overscan code ; Wait for VB timer to expire before visible screen WaitOS if INTIM then goto WaitOS goto NextFrame