So, can anyone make an open hardware version of this chip? Have the patents run out? It's been 45 years, and I understand they only last 25 years. A side question would be which CPU architectures are openly available now that are capable of running a modern Linux distro?
The patent situation is such that one could manufacture a 32-bit x86 processor without the various SIMD and virtualization extensions and not have to worry about patents on the abstract architecture. Implementation techniques up to and almost including the Pentium Pro (November 1995) would likewise be safe from patent threats. However, semiconductors get explicit treatment under copyright law (http://copyright.gov/title17/92chap9.html), so you have to do your own layout until such time as copyrights start expiring again.
