PAPER 1 • BOOLEAN ALGEBRA

D-Type Flip-Flops

A D-type flip-flop stores one bit of data and acts as a simple memory element inside digital systems.
It reads the D input only at the rising edge of the clock, then holds that value at Q until the next rising edge.
Use the simulator to build the circuit, then complete the timing diagrams to show how the output changes over time.

Visual channel

Dual coding

Verbal channel

A D-type flip-flop is a positive-edge-triggered circuit.
It has two inputs: a data input D and a clock input C.
It has two outputs: Q and ¬Q, where ¬Q is the inverse of Q.
At each rising clock edge, the output Q copies the value currently on D.
When the clock is not rising, the circuit keeps its previous value and behaves like a 1-bit memory store.

Activity 1

Build a D-Type Flip-Flop Circuit

Use the simulator to build a D-type flip-flop circuit using only the sequential components shown in the palette.
Add an INPUT D, a CLOCK, a DFF and the sequential output blocks for both Q and ¬Q.
Wire the data input into the D input of the flip-flop, wire the clock input into the clock pin, then connect the two flip-flop outputs so the circuit shows both Q and ¬Q.

Sequential gates only

Construct the D-type flip-flop circuit

Open standalone simulator

State the purpose of a D-type flip-flop circuit. Describe the inputs and outputs used by a D-type flip-flop circuit, explaining how the inputs are used to control the outputs.

Activity 2

Complete the Output Timing Diagrams

Each card shows a different D input pattern and clock cycle.
Click the cells in the Q row to draw the output graph. Think about what happens only at the rising edge of the clock.
The output holds its previous value until the next rising edge arrives.