- Terms:
- Port: a port is a point of connection on a component, such as a
gate, to a wire.
- Node: a node is a collection of wires that are electrically
connected.
- Component: a component is typically a gate or a device that has
input ports and output ports.
- Propagational delay: it takes a short amount of time for a component
to update its output port(s) after at least one of the input ports is
changed. This amount of time is called a propagational delay.
In pseudocode, the logic can be summarized as follows:
- Begin with a starting state.
- Make initial changes to one or more input pins.
- Perform the following steps until there is no change from the last
step (PD row):
- This is a NC (node connectivity) row. Depending on the
wiring of the circuit, update all other ports of the same node
connected to a port that is changed.
- This is a PD (propagational delay) row. After a propagational delay,
analyze and compute the output port(s) of every component that has at
least one input port changed in the previous step.
- Only record in the table if an output port is changed from its
current value.
Mechanically, this can be done by using a spreadsheet or any
table.
