[LordKeren]

Typically I see “u” used in instances where it is the actual SI Unit prefix for 10^-6, and leaving it as “mirco” is used when in its more common form for “very small”

[twic]

The only exception i can think of off hand is "uP" as a very rare abbreviation for "microprocessor": https://www.pcmag.com/encyclopedia/term/microprocessor

[jnordwick]

micro-operation in a CPU is uop.