Linked by Thom Holwerda on Tue 12th Nov 2013 23:06 UTC
PDAs, Cellphones, Wireless

I've always known this, and I'm sure most of you do too, but we never really talk about it. Every smartphone or other device with mobile communications capability (e.g. 3G or LTE) actually runs not one, but two operating systems. Aside from the operating system that we as end-users see (Android, iOS, PalmOS), it also runs a small operating system that manages everything related to radio. Since this functionality is highly timing-dependent, a real-time operating system is required.

This operating system is stored in firmware, and runs on the baseband processor. As far as I know, this baseband RTOS is always entirely proprietary. For instance, the RTOS inside Qualcomm baseband processors (in this specific case, the MSM6280) is called AMSS, built upon their own proprietary REX kernel, and is made up of 69 concurrent tasks, handling everything from USB to GPS. It runs on an ARMv5 processor.

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RE: Comment by shmerl
by Carewolf on Wed 13th Nov 2013 16:52 UTC in reply to "Comment by shmerl"
Carewolf
Member since:
2005-09-08

Beyond all those that run on their own chips for specific components there is also a low power operating system in most phones that run when the phone is powered off. Its main job is to react to power button key events.

edit: typos

Edited 2013-11-13 16:53 UTC

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