A baseband processor is a chip that manages the cellular radio functions of a device. In the case of iDevices, the baseband processor has its own RAM and firmware, separate to the main processor.
Over the years, Apple has used many different baseband processors. Specifically, Broadcom and Intel are the most common, but Infineon has been used before. Recently, Apple has begun utilizing two processors at the same time. In other words, newer devices support two processors (one Broadcom, one Intel), but which one is used in your device depends on many factors.
This list is sorted roughly in chronological order. The devices listed to the right of each processor model number are the devices it is used in.
iPhone3,2models), iPad 2 (
iPhone3,3model), iPad 2 (