Anyone looking for support or advice on old products or custom apps from Adit Limited (1988 to 2019) can contact the founders via the Contact page.
This web site supports three technical books.
You will find all of the code from the books organised by chapters together with some additional materials.
There are occasional blog posts related to Arduino projects that can be found here.
More general technical blogging on C#, .NET and so on lurks here.
A new JavaScript blog can be found here.