Micro-Operation (Micro-Ops or µOP) is a simple internal representation of an architectural instruction as handled by the microprocessor. While exact definition of µOPs varies across implementations, the idea is to greatly simplify the internal representations of operations. It is generally associated with designs that transform more complex (e.g. variable length or multiple operations) instructions with simple single-operation commands however µOPs are also used in many other cases even when instructions are fairly uniform. Additionally, Micro-Operations can also be a result of cracking Macro-Operations. It's a common misconception that micro-operations are exclusively a CISC concept. While more often associated with CISC ISAs such as x86 and z/Architecture, micro-ops are also used in various RISC designs such as ARM and POWER.

Nomenclature

• Intel refers to the internal operations of fixed length, regular format, and encoding a micro-operation. Those are a result of decoded macro-operations.
• AMD refers to the simple, single-operation (e.g. a single arithmetic or memory operation) a micro-operation. Those µOPs makes up a potentially more complex macro-operation.
• ARM refers to the internal representation of instructions as micro-operation. Those are a result of decoded instructions or may be part of a group of µOPs as macro-operation.