A simulator for a digital system comprises a simulation model, an event
queue for scheduling changes to the state of the simulation model at
specified times, and a separate delta queue, for scheduling changes to the
state of the simulation model that are to take place instantaneously. The
use of separate event and delta queues facilitates optimization of the
queuing. The simulation model comprises a number of replaceable parts,
each of which contains and is responsible for managing its own state
information. The event and delta queues contain references to the parts of
the model for which changes of state are scheduled, without containing the
actual values of those changes of state.
