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Inside Macintosh: Devices /
Chapter 6 - Power Manager / Power Manager Reference
Power Manager Dispatch Routines / Determining the Power Manager Features Available


You can use the PMFeatures function to find out which features of the Power Manager are implemented.

unsigned long PMFeatures();
The PMFeatures function returns a 32-bit field describing hardware and software features associated with the Power Manager on a particular machine. If a bit value is 1, that feature is supported or available; if the bit value is 0, that feature is not available. Unused bits are reserved by Apple for future expansion.
Bit nameBit numberDescription
hasWakeupTimer0The wakeup timer is supported.
hasSharedModemPort1The hardware forces exclusive access to either SCC port A or the internal modem. (If this bit is not set, port A and the internal modem can be used simultaneously by means of the Communications Toolbox.)
hasProcessorCycling2Processor cycling is supported; that is, when the computer is idle, the processor power will be cycled to reduce power use.
mustProcessorCycle3The processor cycling feature must be left on (turn it off at your own risk).
hasReducedSpeed4Processor can be started up at a reduced speed in order to extend battery life.
dynamicSpeedChangeXProcessor speed can be switched dynamically between its full and reduced speed at any time, rather than only at startup time.
hasSCSIDiskMode6The SCSI disk mode is supported.
canGetBatteryTime7The computer can provide an estimate of the battery time remaining.
canWakeupOnRing8The computer supports waking up from the sleep state when an internal modem is installed and the modem detects a ring.
hasDimmingSupport9The computer has dimming support built into the ROM.

The trap is _PowerMgrDispatch ($A09E). The selector value for PMFeatures is 1 ($01) in the low word of register D0. The 32-bit field of supported features is returned in register D0.

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© Apple Computer, Inc.
3 JUL 1996