No, you do not have to re-program a VISTA System when you replace the PROM chip. All of the programming settings and configurations for the system will remain set as they were before. Once the PROM chip is replaced, and the panel is powered back on, the update will be automatically applied. Replacing a PROM Chip serves as a way to upgrade a Honeywell VISTA System. This can be necessary for unlocking certain functions and features on the system. One of the most important reasons to replace the PROM chip for a VISTA is to gain access to Total Connect 2.0. This is an interactive service platform available exclusively for Honeywell Systems. Being able to access this service can make controlling an alarm system much easier. At this time, Alarm Grid offers PROM chip upgrades for the VISTA-15P, VISTA-20P and VISTA-21iP Systems. You will not have to reprogram your Honeywell VISTA Security System upon replacing the PROM chip. All system zones will remain programmed, and all system user codes will still be usable. Complete the following steps to replace a Honeywell VISTA System PROM Chip: 1. Power down the system. Before replacing the PROM chip, you must power down the system. Failing to do so could result in serious damage to your panel. To power down the system, first disconnect the backup battery. Then unplug the transformer. The system will power down, and the keypad will go blank. 2. Remove the old PROM. Locate the PROM chip inside the system. You can identify the small chip as a small black square. The picture shown above after the first paragraph actually shows a Version 9.12 PROM chip for a VISTA-20P. The old PROM chip for your VISTA should look similar. Take a binder clip or a similar tool and carefully pry the PROM chip from the system. 3. Apply the new PROM. Take your new PROM chip and put it in the previous location of the old PROM chip. Press it down, and it should snap into place. Make sure it is nice and secure. 4. Power on the system. Plug the transformer back into the wall outlet. This should power the system back on. After the reboot process is complete, the update should be automatically applied. You can then reattach the backup battery.