that they need attention, want to communicate, etc. Although polling can be very simple, in many situations (e.g., multitasking operating systems) it is more efficient to use interrupts because it can reduce processor usage and/or bandwidth consumption. Poll message A poll message is a control-acknowledgment message. In a multidrop line arrangement (a central computer and different terminals in which the terminals share a single communication line to and from the computer), the system uses a master/slave polling arrangement whereby the central computer sends message (called polling message) to a specific terminal on the outgoing line. All terminals listen to the outgoing line, but only the terminal that is polled replies by sending any information that it has ready for transmission on the incoming line. In star networks, which, in its simplest form, consists of one central switch, hub, or computer that acts as a conduit to transmit messages, polling is not required to avoid chaos on the lines, but it is often used to allow the master to acquire input in an orderly fashion. These poll messages differ from those of the multidrop lines case because there are no site addresses needed, and each terminal only receives those polls that are directed to it. See also Abstraction (computer science) Asynchronous I/O Bit banging Infinite loop Interrupt request (PC architecture) Integer (computer science) kqueue Multiple asynchronous periodic polling Pull technology select (Unix) Signal (IPC) References Events (computing) Input/output fr:Attente active