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PATH Hardware Documentation
> PowerBook G3 Series 1999
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RTAS (Run-Time Abstraction Services) can be thought of as a BIOS (basic input/output system). RTAS code handles hardware accesses needed by an operating system, making it possible for multiple operating systems to get hardware services without having to know the specifics. RTAS handles hardware-specific services such as NV-RAM (containing parameter RAM), time services (the real-time clock), PCI configuration cycles, power management, and the code needed to restart and shutdown.
RTAS is relocateable code; its location in RAM is determined by the operating system, and it remains functional after the operating system boots.
Note
RTAS is part of the system software. It is not needed by applications, which use operating system APIs.
