Sequential Circuit Simulator
Design and test sequential circuits with flip-flops and latches.
What are Sequential Circuits?
Sequential circuits are digital circuits whose outputs depend not only on the current inputs but also on the past inputs (the circuit's state). They have memory, unlike combinational circuits.
Basic Sequential Elements
D Flip-Flop
The D (Data) flip-flop captures the value of the D input at the moment of a rising (or falling) clock edge and holds that value until the next clock edge.
| Current State (Q) | D | CLK | Next State (Q) |
|---|---|---|---|
| 0 | 0 | ↑ | 0 |
| 0 | 1 | ↑ | 1 |
| 1 | 0 | ↑ | 0 |
| 1 | 1 | ↑ | 1 |
JK Flip-Flop
The JK flip-flop is a universal flip-flop that can be used for set, reset, hold, or toggle operations based on the J and K inputs.
| Current State (Q) | J | K | CLK | Next State (Q) | Operation |
|---|---|---|---|---|---|
| X | 0 | 0 | ↑ | Q | No Change |
| X | 0 | 1 | ↑ | 0 | Reset |
| X | 1 | 0 | ↑ | 1 | Set |
| X | 1 | 1 | ↑ | ~Q | Toggle |
Applications of Sequential Circuits
- Counters: Circuits that count clock pulses and produce a specific sequence of states.
- Shift Registers: Circuits that shift data from one flip-flop to another on each clock pulse.
- Memory Elements: Flip-flops and latches are used to store information in memory devices.
- State Machines: Circuits that transition between different states based on inputs and current state.
State Tables and Timing Diagrams
Sequential circuits are often described using state tables and timing diagrams:
- State Tables: Show how the circuit transitions between states based on inputs.
- Timing Diagrams: Show how signals change over time, including clock pulses, inputs, and outputs.
Sequential Circuits in Computer Science
Memory and Storage
Sequential circuits form the basis of computer memory. From individual flip-flops to complex memory arrays, these circuits allow computers to store and retrieve information.
Processor Design
CPUs use sequential circuits for registers, counters, and control units. These elements store intermediate results, track program execution, and coordinate the operation of different components.
A-Level Exam Tips
In A-Level Computer Science exams, you may be asked to analyze sequential circuits, complete state tables, or design simple sequential circuits. Focus on understanding the behavior of different flip-flops and how they can be combined to create more complex circuits.