f/w

(firmware) abbr. See firmware.

FAA

(as letters) abbr. Federal Aviation Administration.

factorial

n. The product of all positive integers from 1 to a given number. Expressed as n!.

Example: 5! = 5 4 3 2 1 = 120.

fail-safe

adj. Said of a strategy that handles errors in a way that ensures the system will go into a nondangerous mode if the software or hardware crashes. It is often thought that fail safe means the system cannot fail. That s impossible because everything physical can break. Instead, a fail-safe system dies in a safe mode: the nuclear power plant that shuts down instead of melting down, the ABS brakes that turn control over to a backup mechanical hydraulic system, and so on.

Fail Safe

N. A fascinating 1964 movie about what happens when a system fails in an unexpected mode. Starring Dan O Herlihy, Walter Matthau, Frank Overton, Henry Fonda, and Larry Hagman. Directed by Sidney Lumet.

failover

Example: In the case of the space shuttle, a watchdog checks that one of the computers has generated engine power calculations every 18 ms. If it fails to produce the calculations in that time, then it will failover to a hot backup, which already should have performed those calculations.

failure

n. An unwanted operation of a system. Failures might be relatively benign or even unnoticed, as when a watchdog resets the system without notifying the user. Others can result in death and destruction. See Clementine, Mars Pathfinder,...