Original: Instruction set architecture , or ISA , is the abstract image of a computing system that is seen by a machine language ( or assembly language ) programmer , including the instruction set , word size , memory address modes , processor registers , and address and data formats .
Simplified: Instruction set architecture , or ISA , is the abstract model of a computing system that is seen by a machine language ( or assembly language ) programmer , including the instruction set , memory address modes , processor registers , and address and data formats .