it looks like asynchronous sequential circuit.
here, Next state, $Y = x \oplus y$ , where $x$ is input , $y$ is present state
Present state $y$ |
input
$x$ |
Next state $Y$ |
0 |
0 |
0 |
0 |
1 |
1 |
1 |
0 |
1 |
1 |
1 |
0 |
At $x=0$, circuit reach to stable state, if y is $0$, it will remain $0$, or if it is $1$ it will remain $1$.
At $x=1$ , states goes $0$ to $1$ , $1$ to $0$, so on , will not reach to stable state.
At $x=y$, next state will remain always at $0$, as seen in table.
so , At $x=1$ , the above circuit will generate the sequence of 0,1,0,1.. , can be used as clock generator.