When the worker process needs to execute I / O or other asynchronous activity, it initiates the action, marks what it is waiting for, and calls the context-switching function, which selects a different context for execution.
12.
Most phreaking boxes are electronic devices which interface directly with a telephone line and manipulate the line or the greater system in some way through either by generating audible tones that invoke switching functions ( for example, the red box.
13.
Note, however, that the BNS and ST2 models do not use Coulomb's law directly for the electrostatic terms, but a modified version that is scaled down at short distances by multiplying it by the switching function " S ( r ) ":
