Circuit patterns
Understand reusable circuit blocks and the role of feedback.
Combinational circuits
In a combinational circuit, the output depends on the current inputs. Gates, adders, and multiplexers are examples.
Build and check a small block before combining it with others. A truth table is useful for checking every input combination.
Reuse a structure
A useful circuit pattern separates a problem into smaller parts. A full adder combines two half adders; a multiplexer combines two selectable paths.
Arrange these parts so their inputs and outputs are easy to follow. Use the same convention when building a larger circuit.
Feedback and memory
Sequential circuits depend on both current inputs and stored state. Feedback, where an output connects back to an earlier part of the circuit, is one way to build memory.
An SR latch uses two cross-coupled NOR gates. Set and Reset control which state it stores.
This diagram illustrates the feedback structure. Gately’s current simulator does not provide a reliable latch memory model, so the example should not be used to verify stored state or timing behavior.
Where to continue
Use half adders, full adders, and multiplexers to explore larger combinational circuits. Check each block on its own, then verify the combined result.