The collection of assembly/machine instruction set of the machine and the machine resources (memory and programmer-accessible registers) that can be managed with these instructions is called Instruction Set Architecture ( ISA(Instruction Set Architecture) The collection of assembly/machine instructions of the machine and the machine resources (memory, general purpose registers, …etc.) that can be managed with these instructions). An Assembly programmer must understand the ISA of the specific machine he is writing codes for in order to write correct programs.
Fig. m010133.1 shows a few examples of the ISA of several machines.