[puetzk]

There's actually a 3rd x86 license, that has changed hands quite a few times (Cyrix -> National Semiconductor -> Centaur(IDT) -> VIA -> Zhaoxin, I think, unless I missed a few transitions?)

There's also the https://opencores.org/projects/ao486 - the relevant patents on a 486-era design would have expired

[userbinator]

The Pentium patents have expired too, and if we go by the usual 20-year expiry, then that would mean everything up to the Pentium III (1999) would be in the public domain. IANAL.

[garmaine]

Patents have expired. That doesn't make it public domain.

[jecel]

Isn't the point of patents that instead of ideas being kept secret (and often vanishing when their inventors die) they are published in exchange for a limited time monopoly on their use? In that case when a patent expires it does indeed become public domain.

[garmaine]

Public domain means no IP applies. Patents are only one kind of IP. There’s also copyrights, trademarks, etc.

[jecel]

Sure, Intel didn't have any serious patents on the 8080 but they did copyright the assembly language mnemonics. So the Z80 was 100% compatible at the binary level but had to use other names for the instructions. Same thing with trademarks.

What I was saying is that what is described in the patent text can be freely used after the patent expires.

[Taniwha]

and at least 2-3 other attempts at cloning I know of including Linus's Transmeta and the one I worked on