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BLOCKDIAGRAM · COMBINATIONAL LOGIC

Combinational Logic Block Diagrams

Combinational logic circuits are the building blocks of digital systems, where outputs depend solely on current inputs. From simple gates to complex ALUs, visualizing these circuits as block diagrams is key to understanding and design.

4 EXAMPLES· UPDATED 2026-08-01
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COMBINATIONAL LOGIC

4-bit Adder-Subtractor Block Diagram

COMBINATIONAL LOGIC

4-Input Population Counter

DIGITAL LOGIC

8-to-3 Priority Encoder

DIGITAL LOGIC

BCD to 7-Segment Decoder

ABOUT

About these examples.

See it in action

Browse our gallery of combinational logic block diagram examples: 4-bit adder-subtractor, priority encoder, BCD to 7-segment decoder, and a population counter. Each shows how logic blocks come together to solve real problems.

Make your own

Ready to build? Use the combinational logic block diagram generator below. Drag-and-drop logic blocks, connect wires, and verify your design instantly.

HOW TO

Make one yourself.

  1. 1

    Open the block diagram generator

    Launch the tool and select a blank canvas or a pre-built template for combinational logic.

  2. 2

    Add logic blocks

    Drag standard gates (AND, OR, XOR, etc.), decoders, multiplexers, or custom blocks onto the workspace.

  3. 3

    Connect the blocks

    Wire inputs and outputs to match your truth table. Use buses for multi-bit signals.

  4. 4

    Simulate and verify

    Toggle inputs and watch outputs update in real time. Confirm the circuit behaves as expected.

  5. 5

    Export or share

    Download as PNG, SVG, or PDF, or generate a shareable link for your team.

FAQ

Frequently asked questions

What is a combinational logic circuit?01
A combinational logic circuit is a digital circuit where the outputs depend only on the current combination of inputs, with no memory of past states. Common examples include adders, encoders, decoders, and multiplexers.
What are some common combinational logic blocks?02
Typical blocks include basic logic gates (AND, OR, NOT), exclusive-OR gates, multiplexers, demultiplexers, encoders, decoders, comparators, and arithmetic functions like half/full adders.
How do I create a block diagram for a 4-bit adder?03
Start by placing four full-adder blocks in parallel. Connect the carry-out of each stage to the carry-in of the next. The A and B inputs form the two 4-bit numbers, and the sum outputs produce the result.
Can I simulate my combinational logic circuit in ChatDiagram?04
Yes, the block diagram generator includes interactive simulation: click input ports to toggle high/low and see outputs change instantly.
What export formats are supported?05
You can download your diagram as PNG, SVG, or PDF. A shareable URL is also available for collaboration.
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