Abstract: A security device for use with equipment having a microprocessor that produces a warning from a warning device such as an alarm if the equipment is changed from a predetermined condition. The change from the predetermined condition can be caused by loss of power to the equipment, physical movement of the equipment, or both. The security device includes an interface means to allow information such as passwords, battery checks, alarm tests, and alarm arming sequences to be passed between the equipment (via its microprocessor) and the security device. The warning device includes a latching mechanism for continuously producing the warning signal until some reset action is undertaken. A password can be used to arm the warning device. If the equipment is powered by a standard AC power outlet common in walls, the security device can include a reset that involves reconnecting the AC power supply.