PROBLEM STATEMent:  mobile and portable computing devices powerable by DC power.

                               given that  power sources are battery and  direct ac to dc via adapter sources

Opportunity : Thus given the content when simultaneous source of power from both a battery and dc source
                   direct via adapter are there ....potential to burn the PCB ...voltage variation or other means
                   ....a virus other program that can engineer such a feat ...by controlling devices or components
                   on a PCB....by making use of the logic-gates concept.

                   thus deriving innovative or efficient circuit-design...to avoid ...loop-hole as illustrated above,
                   objective to be able to use or power a device using both direct dc source [ when battery is absent],
                   and powered by battery when mobile ...such that above scenario is taken care of.


Note: The above problem statement having been encountered in various scenarios
        and detailed in various 'Proof of concepts' as mentioned in 
      
       http://uk.geocities.com/ravivenkatus/projects.pdf
       http://ravishankarkv.tripod.com/projects.pdf
        ....apply appropriate
      'use-case' modeling, rationalize and arrive at a workable and feasible 
       solution both commercially and techinically viable.

 
 