When the Terminator, the teen John Connor, Sarah Connor and Miles Dyson go to the Cyberdyne Systems Corporation building in order to destroy any data that could lead to Skynet's creation (and therefore to Judgment Day), the alarm is raised by the reception guards and as a consequence all entry panels are deactivated.
At this point Miles Dyson's knowledge is useless. He knows the codes but everything is remotely blocked. John Connor uses his "Pin cracker" device, used for cracking ATMs, and tries to get the code and so open the safe.
But here's the problem... Myles Dyson already knew the codes. There was no need to "get them" illegally. The problem is not there, the problem is that the panels are blocked anyways, codes are irrelevant. Not to mention that an ATM probably works very differently from a security panel in a secret research building.
Am I missing something?