I have referenced a COM dll (unmanagged code) in a C# console application and this DLL is referenced in C# program using Interop facility in .NET. This dll actually a dataset/table which is written in Borland Delphi.

Code:
static int Main(string[] args)
{

ClientVarDataSet vds = new ClientVarDataSet();
vds.XML = "";

vds.AddField("x", 3); //"x" field name and
...