Junction node
A branch point on a wire. The node takes the signal arriving on its input and repeats it, unchanged, on up to three branches, so one source can reach several destinations. It carries no logic and adds no delay — it is the drawing of a shared connection, not a component that does anything to the signal.
You do not place it — you create it
The node is the one part that never comes from the palette. Start dragging from an input terminal that has nothing wired to it, and drop the end onto the middle of an existing wire: a node appears at that point and both destinations now receive the same signal. Drop further input terminals onto that node to reuse its remaining branches.
One clock, many destinations
A clock that has to reach three flip-flops is the everyday case. Wire the clock to the first flip-flop, then drop the other two clock inputs onto that wire. Each drop makes a node, and all three flip-flops now sample on the same edge. Without nodes you would be drawing three separate wires from the same source, which is harder to read and easy to get wrong.
Three branches, and what to do past that
A node offers three branches, which is a drawing limit, not an electrical one. When a signal has to reach a fourth destination, drop onto one of the branch wires and a second node appears there — nodes chain, so the fan-out is effectively unbounded. The branches inherit the width of the wire they were tapped from, so tapping a bus gives you the whole bus on every branch, not one of its bits; use a Splitter when you want a single line out of a bus.
Citations
- Harris, D. M., & Harris, S. L. (2012). Digital design and computer architecture (2nd ed.). Morgan Kaufmann. Reference 1
- Mano, M. M., & Ciletti, M. D. (2018). Digital design: With an introduction to the Verilog HDL, VHDL, and SystemVerilog (6th ed.). Pearson. Reference 2