Energy Saver Control Panel: Sleep and Power Management

This article provides details about the "Sleep" and power management functions of the Energy Saver control panel shipping with the Power Macintosh 7200, 7500, and 8500 series computers.

Questions answered in this article:

1) Is the central processing unit (CPU) still responsive when the Energy Saver control panel spins down the hard disk in sleep mode?

2) Is it possible to spin down the hard disk, but not put the monitor into sleep mode?

3) Can the Energy Saver control panel spin down any hard disk attached to the SCSI bus, or only the startup disk?

4) When does the Energy Saver control panel begin the countdown before putting the computer to sleep or shutting down? Is there a specified delay, or does the countdown begin as soon as the computer is idle?

5) If the computer is in sleep mode, and a fax call comes in (assuming the fax software is set to receive faxes), does my computer wake up and receive the fax?
1) Question: Is the central processing unit (CPU) still responsive when the Energy Saver control panel spins down the hard disk in sleep mode?

Answer: While in sleep mode, the CPU responds to mouse, keyboard, and serial port activity. If an activity requires disk access, the hard disk is spun up.


2) Question: Is it possible to spin down the hard disk, but not put the monitor into sleep mode?

Answer: Yes, it is possible for the hard disk to spin down even though the monitor is not in sleep mode. When the hard disk is spun down, the arrow is unresponsive (as if the system is unresponsive), but pressing a key spins the hard disk back up. However, there is a delay before the drive spins back up, and there is no notification that the drive is spinning back up.


3) Question: Can the Energy Saver control panel spin down any hard disk attached to the SCSI bus, or only the startup disk?

Answer: The Energy Saver control panel may or may not spin down all hard disks attached to the SCSI bus. Apple has not tested The ability to spin down a hard disk is dependent on the formatting software used on the hard disk. In limited testing, the Energy Saver control panel has spun down external drives formatted with Drive Setup.


4) Question: When does the Energy Saver control panel begin the countdown before putting the computer to sleep or shutting down? Is there a specified delay, or does the countdown begin as soon as the computer is idle?

Answer: The countdown to shutdown or sleep begins as soon as the computer is idle. Your computer is idle if when all of the following conditions are met:

- No Apple Desktop Bus (ADB) routines other than routine monitoring of the bus
- No Input/Output (I/O) calls to firmware (Read, Write, Control, Format, Status)
- No changes in the cursor (for example, the rotation of a hand in the clock icon)
- No post-event calls (for example, a call resulting from insertion of a disk)
- No communication through the serial port


5) Question: If my computer is in sleep mode, and a fax call comes in (assuming the fax software is set to receive faxes), does the computer wake up and receive the fax?

Answer: A modem that uses the serial port's 'wake on ring' pin setting, and that has software that reads it, can wake the CPU from sleep. The GeoPort Telecom Adapter from Apple features this capability. Depending on background activity, some fax software may keep the CPU busy and not allow the computer to enter "sleep" mode.
Published Date: Feb 20, 2012