anchor.diff:      let mutable videoCounterBase = 0
       let mutable videoMatrixLineIndex = 0
       let videoMatrixLineMemory = Array.zeroCreate 40
  -    let IncrementVideoCounter () =
  -        videoCounter <- (videoCounter + 1) &&& 0x3FF
  -        videoMatrixLineIndex <- (videoMatrixLineIndex + 1) &&& 0x3F
  -    let IncrementVideoCounterBase () =
  -        videoCounterBase <- videoCounter
  -    let ResetVideoCounter () =
  -        videoCounter <- videoCounterBase
  -        videoMatrixLineIndex <- 0
  -    let ResetVideoCounterBase () =
  -        videoCounterBase <- 0
   
       // Graphics shift registers
       let mutable graphicsShiftRegister = 0
  
positive.code:     //  48  First G fetch
      // 125  Last C fetch
      // 126  Last G fetch (NOTE: this overlaps 0 on PAL systems)
      let memoryAccessCycle = Array.init (config.RasterWidth) (fun counter ->
          if (counter % 4 <> 0) then
              -1
          else
  
negative.code:     // Utility
      // ========================================================================
  
      let getValueFromBit index value =
          if value then 1 <<< index else 0
  
      let getValueFromBits(arr:bool[]) =
          (getValueFromBit 0 arr.[0]) |||
          (getValueFromBit 1 arr.[1]) |||
          (getValueFromBit 2 arr.[2]) |||
          (getValueFromBit 3 arr.[3]) |||
          (getValueFromBit 4 arr.[4]) |||
          (getValueFromBit 5 arr.[5]) |||
          (getValueFromBit 6 arr.[6]) |||
          (getValueFromBit 7 arr.[7])
  
      let setBitsFromValue(arr:bool[], value) =
          arr.[0] <- (value &&& 0x01) <> 0
  