Integer ALU ops. ADD , AND , SUB , OR . Data transfer between memory and registers. OS instructions, virtual memory management instructions.
All machines generally provide a full set of operations for the first three categories.
All machines MUST provide instruction support for basic system functions. Floating point instructions are optional but are commonly provided. Decimal and string instructions are optional but are disappearing in recent ISAs. They can be easily emulated by sequences of simpler instructions. Graphic instructions are optional.