What does the following logic diagram represent ?

Answer: Ripple Counter (2-bit asynchronous counter).

Explanation:

• Each JK flip-flop has J = K = 1, so each flip-flop toggles its output on each active clock edge.

• The external clock is connected to the clock input of only the first flip-flop. The output of the first stage (Q0) is used to drive the clocking of the next stage.

• Because subsequent stages are clocked by the previous stage's output rather than by the common external clock, state changes propagate from stage to stage (they "ripple"), making the counter asynchronous.

• Each stage divides the input frequency by two. With two stages the outputs form a binary count sequence 00, 01, 10, 11 repeating (a mod-4 counter).

• This contrasts with a synchronous counter, where all flip-flops receive the same clock simultaneously; here only the first receives the external clock.