A battery-powered computer chassis intrusion detection circuit which stores the time and date that the chassis hood, components, or AC power was removed. When intrusion occurs, an alarm bit isolates the detection circuit oscillator from the circuit, effectively stopping a real time clock from incrementing the time and date. When the computer is powered back up, internal ROM checks to see if an alarm condition occurred. If so, the intrusion date and time is recorded and the user or administrator may be alerted.