Wireless proximity detector security feature

Abstract

A security system for computers defines a control zone using radiation, preferably at radio frequency, having a distinctive characteristic, such as a particular frequency. The zone may be established, for example, at a door exit or other limited passage to a secured area. Computer systems are provided with receivers that detect the distinctive characteristic and responsively produce an alarm signal which triggers security logic. The security logic cooperates with the start-up logic of the computer and disables start-up so that the computer becomes inoperative. In a more complex variation, the radiation triggers a device in the computer that in turn sends out a serial number signal. A receiver located near the control zone applies the serial number to a table look up computer that triggers an emergency signal if a match to an authorized list of serial numbers does not occur. The emergency signal activates a transmitter that sends out a radiation signal with a second distinctive characteristic. A second receiver in the computer then responds to the radiation with the second characteristic to trigger the security logic to render the computer inoperative.