Sequential Circuits

Sequential circuits are digital circuits with an output that depends on both (1) current inputs and (2) past states (= previous inputs,) unlike combinational circuits which are purely input-dependent and don't store their past state.

• Think of combinational circuits as simple calculators - they give immediate answers but can’t save or remember them.

Sequential circuits retain past information, enabling them to "remember" states due to their ability to store binary data.

By storing these past states, sequential circuits play a key role in tasks that require memory, such as counters, registers (e.g., CPU registers,) and finite state machines. These circuits are critical in designing memory elements, control units, and other parts of a computer that rely on tracking past operations.

• Memory and state storage are essential in designing CPUs, memory units, and control units, which can’t be done with combinational circuits alone.