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After starting the program, it automatically minimizes itself into the system tray. It can be identified by one of four different icons which indicate the current CPU policy:

Icon	CPU policy	means ...
	Max. performance	keeps the CPU at maximum speed (i.e. a Pentium-M 1.6 GHz runs at 1.6 GHz continously)
	Battery optimized	keeps the CPU at the lower speed (i.e. a Pentium-M 1.6 GHz runs at 600 MHz continously)
	Max. battery	Keeps the CPU at the lower speed and allows further throttling depending on remaining battery power
	Dynamic switching	switches between the lower and maximum speed according to current CPU utilization (i.e. a Pentium-M 1.6GHz switches automatically between 600 MHz and 1.6 GHz)

If you move the mouse pointer over the tray icon, you see the current CPU policies for AC (external power) and DC (battery power) in a small popup window:

A rightclick on the tray icon opens a small window which allows fast switching between the different CPU policies:

When changing the CPU policy, the tray icon changes automatically to reflect the new CPU policy.

A leftclick on the tray icon opens the main window. It looks like this:

On the main window, you can change the CPU policies for both external and battery power. The program automatically switches between the external and battery CPU policies when a power state change occurs (pulling the AC plug or plugging it back in). You can also adjust the main power options here like display timeouts, HD spindown timeouts, etc.

Clicking on 'Detect max. speed' activates the detection of the CPU's maximum speed. This process takes approximately two seconds.

Clicking on the options button shows the options window:

These options have the following meaning:

• Enable Autostart
  Activates the autostart functionality. When activated, the program will be started automatically on every boot.
• Enable Debugmode
  Activates the debug mode. When in this mode, the program writes runtime log messages to the log file "SpeedswitchXP.log".
• Minimize To Tray...
  When activating this option, the program will be minimized to the tray instead of shutting down when clicking on the 'Close' button.
• Reactivate previus power scheme when terminating
  Reactivates the power scheme that was active at program start when the program is terminated.
• Check power scheme integrity
  Checks the power scheme "Speedswitch Control" on the given interval for changes from outside the program. When detecting a change, the program restores the power scheme settings to its original values.
• Read CPU speed
  Activates the CPU speed detection in certain intervals. The CPU speed can be detected by two methods: receiving the current speed from Windows XP ('Ask Windows about speed') or calculating the current speed in realtime ('Realtime speed calculation'). You can also enable a separate tray icon which shows the CPU speed by enabling the option 'Show in tray icon'.
• Read CPU load
  Detects the current CPU load in certain intervals. You can also enable a separate tray icon which shows the CPU speed by enabling the option 'Show in tray icon'. If both these options here and for the CPU speed are activated then there's only one icon showing the speed in its upper part and the load in its lower part.
• Show history diagram
  Displays the detected CPU speeds and loads in the history diagram on the main window. The CPU speed is displayed in 100MHz units and can be scaled to get a clearer speed display.
• Show battery level in tray
  Displays an additional tray icon which shows the remaining battery capacity:

  

  The program can display the battery icon only when the system runs from battery ('Only when on battery power') or when running both from AC or battery. The value shown in the tray icon can be either the remaining battery charge in % or the remaining battery time in minutes. When moving the mouse pointer over the tray icon, both values are shown in a small popup window:

  .

  The option 'Indicate battery charging status' shows a charging battery icon if the battery is currently being charged. In this mode, the icon automatically displays the remaining battery charge in percent so you can observe the charging status:

  

• Update interval
  Determines the update interval for the CPU speed, CPU load, and battery capacity detection.

The 'User policy', 'Machine policy' and 'CPU policy' tabs take you to the internal settings of the power scheme. Before you make any changes to these internal settings you should teach yourself on their internal functionality. I suggest that you read these documents to fully understand their meaning:

• Windows XP native processor performance control
  
• User policy settings
• Machine policy settings
• CPU policy settings

If you want to know even more about processor control and C-states then take a look at these sites:

• ACPI specification 2.0a
  
• Microsoft ACPI/Power Management site

Clicking on the 'Show system info' button on the main window brings up a window showing some info about the CPU and your system's power capabilities:

The second window tab shows your system's power capabilites:

Last Update: 29. June 2006 Christian Diefer