micro-operation
/ˌmʌɪkrəʊˌɒpəˈreɪʃn/noun
1 Biology and Surgery. An operation performed under or with the aid of a microscope.
2 Computing. A simple operation carried out in response to a microinstruction.
Origin
Early 20th century; earliest use found in Journal of the Royal Microscopical Society. From micro- + operation.