The 8-bit microprocessors invented in the seventies, had a 16-bit address space. It didn't take long for memory demand to exceed this, with the result that bank switching was a fact of life for the remainder of the lifespan of those architectures.
Many different bank switching schemes were used. The one I'm interested in is the flexible and logically simple one where the 64K address space is divided into pages of size X, each of which can be independently mapped onto any X-sized and aligned section of physical RAM. This was used by the CoCo 3 (8K granularity) and according to the answer to this question, also by the Cambridge Z88 and Enterprise 128 (16K granularity): Which memory management is easiest to program - CoCo 3 or C128/Apple //e?
I imagine someone must have been awarded a patent for that scheme at some point, but Google searches on relevant keywords are just turning up patents on somewhat related but different things. I might guess it would be patented around the early eighties, but one thing I have learned in studying the history of computing is that most things go back a lot further than you think.
Was that bank switching scheme ever patented, and if so, when?