The article explains: > Though you can not patent an instruction set, you can patent machines and methods that are necessary to implement a particular unusual

The article explains: > Though you can not patent an instruction set, you can patent machines and methods that are necessary to implement a particular unusual instruction that is part of the instruction set. That legally blocks competitors from creating a fully compatible clone of your processor. The author is making a very clear and correct distinction. It continues: > There are four instructions in the MIPS-I instruction set that were protected by one US patent, 4,814,976. These instructions, lwl, lwr, swl, and swr are known as the unaligned load and store instructions.