The secret second operating system that could make every mobile
phone insecure  Qualcomm's MDM9600 baseband chip  Share This
article  When we talk about computers — PCs, smartphones, cars —
we generally assume that there’s just one operating system: A
single, monolithic piece of software that manages each
individual piece of hardware, from the CPU to the USB controller
to the wireless connectivity. If your system crashes, we nearly
always blame the operating system, or perhaps a software driver
that links into the OS. In just about every computer science
textbook, a computer consists of just three blocks: the
hardware, the operating system, and then all the (user-land)
software that runs on the OS. In actual fact, unbeknownst to the
user, almost every computer has multiple operating systems
running at the same time, managing various different parts of
the computer — and worryingly, these OSes are usually
proprietary, closed-source, bug-ridden, and have extensive, low-
level access to your data.  Take your smar