NetBSD is known as a very portable operating system, currently running on 44 different architectures (12 different types of CPU). This paper takes a look at what has been done to make it portable, and how this has decreased the amount of effort needed to port NetBSD to a new architecture. The new AMD x86-64 architecture, of which the specifications were published at the end of 2000, with hardware to follow in 2002, is used as an example.