He also co-founded Transversal, a software company that specialises in search based on natural speech and wrote the textbook "Information Theory, Inference, and Learning Algorithms", available online for free.
In the wider world MacKay is best known for his 2008 book
“Sustainable Energy - Without the Hot Air,, which had a major impact on thinking about energy. Within nine months, MacKay was appointed Chief Scientific Advisor to the Department of Energy and Climate Change, a role he occupied until 2014.
Sustainable Energy — without the hot air is here in a 383 page pdf