anchor.diff:          (if rowSelect then 0x08 else 0x00) |||
           yScroll
       let SetControlRegister1 (value:int) =
  -        SetHighRasterYCompareValue(value) |> ignore
  +        rasterYCompareValue <- (rasterYCompareValue &&& 0x0FF) ||| ((value &&& 0x80) <<< 1)
           extraColorMode <- (value &&& 0x40 <> 0x00)
           bitmapMode <- (value &&& 0x20 <> 0x00)
           displayEnabled <- (value &&& 0x10 <> 0x00)
  
positive.code:     let SetLowRasterYCompareValue (value:int) =
          rasterYCompareValue <- (rasterYCompareValue &&& 0x100) ||| value
          value
      let SetHighRasterYCompareValue (value:int) =
          rasterYCompareValue <- (rasterYCompareValue &&& 0x0FF) ||| ((value &&& 0x80) <<< 1)
          value
  
      // Control register 1 (11) (RST8/ECM/BMM/DEN/RSEL/YSCROLL)
      let mutable extraColorMode = false
  
negative.code: 
      // Raster X Counter (for sprites)
      let mutable rasterX = 0
      let IncrementRasterX () =
          rasterX <- if rasterX >= (config.MaxRasterX - 1) then 0 else rasterX + 1
  
      // Blanking
      let mutable vBlank = true
      let mutable hBlank = true
      let ClearVBlank () =
          vBlank <- false
      let ClearHBlank () =
          hBlank <- false
      let SetVBlank () =
          vBlank <- true
      let SetHBlank () =
          hBlank <- true
  
      // Raster Line Counter (not identical to X)
      let mutable rasterLineCounter = 0
      let IncrementRasterLineCounter () =
          rasterLineCounter <- if rasterLineCounter >= (config.CyclesPerRasterLine - 1) then 0 else rasterLineCounter + 1
  
      // RC
      let mutable rowCounter = 0
  