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Inside Macintosh: Devices /
Chapter 6 - Power Manager / Power Manager Reference
Power Manager Routines / Controlling the Idle State


You can use the GetCPUSpeed function to read the current CPU clock speed.

FUNCTION GetCPUSpeed: LongInt;
The GetCPUSpeed function returns the current effective clock speed (in megahertz) of the CPU.

The MPW development system provides an assembly-language macro to execute the GetCPUSpeed routine. That macro calls the _IdleState trap. To call the _IdleState trap directly, you must first put a longword routine selector in the D0 register. For GetCPUSpeed, the routine selector can be any value that is less than 0. The CPU speed is returned as a single byte in register D0.

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© Apple Computer, Inc.
3 JUL 1996