ITPEC FE Morning October 2023 Question 20

Flip-flop — a sequential circuit with feedback that holds one of two stable states, 0 or 1, until an input changes it.

A sequential circuit's output depends on its stored state as well as its current inputs. A flip-flop is the simplest one: it stores one bit, and it is the building block of registers, counters and SRAM cells.

Answer (c)

Why not others:

• •(a) Adder circuit — a combinational circuit: its output depends only on its current inputs and nothing is stored
• •(b) Capacitor — a passive electronic component that stores charge, not a logic circuit; DRAM uses it but must refresh it
• •(d) NAND gate — a single combinational gate; two cross-coupled NAND gates can form a latch, but one gate has no memory

Key rule: Combinational circuits (gates, adders, decoders) have no memory; sequential circuits (flip-flops, registers, counters) keep state.

Hardware · AI-written, may contain errors