A computer graphics and analysis application improvement providing calculation, regeneration, and display of mechanism solutions based on inputted desired functions such as part positions by extracting functional requirements data from such inputted data so that the designer or engineer can view the mechanism solutions in space and thereby design the desired mechanism or mechanisms. The display utilizes a closed loop laser scanningmodulating arrangement in which a Position Sensitive Device located next to the screen is used to determine the location of the impinging beam, and to transmit timinglocation data to the laser addressing system. The nitrogen content of the purified product is monitored, and the conditions of the purification step are adjusted to increase nitrogen removal if the nitrogen content of the purified product exceeds a preselected value. Shadow based file-systems realize efficiency gains by employing the deferred mechanism. To further avoid collisions, one or more frames of the response messages can be same, making the multiple responses appear as multi-path.