What is International Solar Alliance (ISA)? The International Solar Alliance (ISA) is an intergovernmental organization that was launched in 2015, by the Prime Minister of India and the President of France, at the United Nations Climate Change Conference held in Paris. The correct answer is Instruction Set Architecture. Key Points An instruction set architecture (ISA), also called computer architecture, is an abstract model of a computer. A device that executes instructions described by that ISA, such as a central processing unit (CPU), is called an implementation. In general, an ISA defines the supported instructions, data types, registers, the hardware support for managing main memory, fundamental features (such as the memory consistency, addressing ... ISA is a common abbreviation that can stand for many different terms, such as Industry Standard Architecture, Individual Savings Account, or International Society of Arboriculture. See the full list of ISA definitions and categories on The Free Dictionary website. ISA can vary significantly between different types of processors, such as x86, ARM, and PowerPC. Each ISA has its own set of instructions and architectural features optimized for specific types of applications, performance requirements, and design goals.