PNP transistor

It identifies the PNP layer order in a circuit.

A transistor switches or amplifies electrical signals. PNP names its P-type, N-type, P-type layers; P-type carries holes (missing electrons), while N-type carries electrons. The emitter arrow points toward the base, following conventional current (positive to negative).

Bell Labs, the U.S. research lab that invented the transistor, proposed its symbol in 1947; a 1961 standards meeting chose it over a rival. The glyph maps to the Japanese character set of Sharp's MZ home computers, where circuit marks could join thin line characters.