reversible counter
A digital counter that can count both up and down, used in computing and digital electronics.
A reversible counter is built into this circuit.
カウンタ is a general term for any counter, while 可逆計数器 specifically refers to a counter that can increment and decrement.
Compound of 可逆 (reversible) and 計数器 (counter). The exact derivation is uncertain, but the term is formed from standard technical kanji.