SR latch, S = 1, R = 0 — flip-flops
introthe set operation
Answer
Q⁺ = 1
Why this example is worth doing
Asserting S drives Q high and it stays there after S is released, which is the entire point: the circuit remembers. The page introduces the next-state notation Q⁺ here, because a sequential device needs a column for the current state that no combinational truth table has, and getting that extra column into the reader's head early is what makes every later table on the page readable.
Try your own input in the Flip-flops & latches. SR, D, JK and T: characteristic tables, excitation tables and timing diagrams.
How the answer is reached
The probed row
S = 1, R = 0, Q = 0
Output table
| S | R | Q | Q⁺ |
|---|---|---|---|
| 0 | 0 | 0 | 0 |
| 0 | 0 | 1 | 1 |
| 0 | 1 | 0 | 0 |
| 0 | 1 | 1 | 0 |
| 1 | 0 | 0 | 1 |
| 1 | 0 | 1 | 1 |
| 1 | 1 | 0 | 1 |
| 1 | 1 | 1 | 1 |