[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.