It really isn't a chip in the VATS (Vehicle Anti Theft System) key. It's a resistor. They used a limited quantity of resistors in these keys. If you have access to a Digital Multi Meter you can check the resistance yourself and tell the key maker what you need. Most good key shops can do it as well.
I was mistaken in my last post about the proper name of the system.
The Vehicle Anti Theft System (VATS) was first installed on the 1985 Corvette. The Personal Anti-theft Security System (PASS-key) replaced VATS in 1988, and while there are some differences, VATS and Pass-key I and II all work the same way. There is no radio communication involved; the system merely looks for the ignition keyÃƒÂ¢Ã¢â€šÂ¬Ã¢â€žÂ¢s unique electronic signature. The PASS-key I & II systems all have a pellet embedded in the ignition key that communicates with the Theft Deterrent Module (TDM). On VATS and PASS-key I, the TDM is hidden deep in the dashboard. On PASS-key II, the TDM is built into the Body Control Module (BCM). The keyÃƒÂ¢Ã¢â€šÂ¬Ã¢â€žÂ¢s visible pellet is a resistor, and you can read its value by touching meter probes to the contacts on either side of the pellet. With the key in the ignition, the pellet touches contacts in the lock cylinder. These contacts are wired to the TDM, which reads the value of the resistor to identify the key. If the resistance is correct, the TDM sends a pulse-width modulated signal to the PCM, which then enables the fuel injectors. The TDM also operates the Theft Deterrent Relay (TDR) that allows power to reach the starter solenoid when the key is turned to the START position. If the TDM doesnÃƒÂ¢Ã¢â€šÂ¬Ã¢â€žÂ¢t recognize the key pellet, it decides a theft attempt is in progress and it will go into anti-theft mode.