Sorry for taking so long to reply, It’s been a battle updating our fleet of Radios.
jmr: Motorola has used the iButton in some shape for many years now. The previous generation of radios, such as the Astro Saber and XTS-3000 used the iButton solely for feature and firmware updating. CPS wouldn’t allow you to do these functions without same, and it would plug into a special RIB box vs the normal one for general programming. The iButtons back then were hacked and people were able to flash any firmware they wanted, as well as any feature they wanted. I am not sure how that as achieved, but it would be cool to learn. Motorola doesn’t care much about those radios as they aren’t used or compatible with modern trunked radio systems.
The next generation of radios, such as the XTS-5000 used a “flash Zap” method as well as the iButton for firmware and feature upgrades. Although, the Depot CPS which was leaked from Motorola allowed you to make any codeplug for these types of radios, with literally any function. A popular one was FPP(Front panel programming) which was a Govt. only feature and make it like a typical HAM radio so you could directly punch in any frequency you wanted. As long as it was a type 3 radio(aka with a keypad).
The newest generation of Motorola radios, such as the APX series utilize the iButton as an Advanced System Key in a USB dongle. This allows the system admin to lock down the radio once it’s programmed. They can also make daughter keys with limited functionality to give to subscribers. It’s come a long was from the previous gen or radios that used a software system key, which was easily hackable with a simple DOS program.