Is there a C# function that formats a 64bit "Unsigned" value to its equivalent binary value?

You can call it unsigned or signed, but its the same if you look at it bitwise!

So if you do this:

Convert.ToString((long)myNumber,2);

you would get the same bits as you would if there were ulong implementation of Convert.ToString(), and thats why there is none... ;)

Therefore, ((long)-1) and ((ulong)-1) looks the same in memory.

Unfortunately there's no direct .NET equivalent like Convert.ToString(ulong, int). You'll have to make your own, like the following:

public static string ConvertToBinary(ulong value){
  if(value==0)return "0";
  System.Text.StringBuilder b=new System.Text.StringBuilder();
  while(value!=0){
    b.Insert(0,((value&1)==1) ? '1' : '0');
    value>>=1;
  }
  return b.ToString();
}