Contents
Turbo for Windows 95 and Windows NT  -  August 1997

Contents  (this topic)

Description

Operation

Menus

Technical Notes

Turbo is a free utility program.  You may redistribute Turbo, as long as all files in the original distribution are included, and no fee is charged except for media.   Turbo is copyrighted.  All rights are retained.  The author does not warrant the suitability of Turbo for any purpose.   The author may be contacted by e-mail: mico@msn.com


Turbo Description

Turbo is a software "Turbo Switch".  You may set the effective CPU speed anywhere from 1 to 100% of full speed.  All programs will execute at the reduced CPU speed set by Turbo.   This could be useful for the following situations:

o	A program designed with CPU timing loops needs to be slowed down to run on a faster CPU than originally intended.
o	A program outputs information very quickly, and overwrites this information before it can be viewed by the user.
o	Software being debugged needs to be slowed down, so that the details of its output sequence can be observed.
o	Software needs to be tested under adverse loading conditions, or its performance on a slower CPU needs to be evaluated.


Operation

To operate Turbo, run the program Turbo.exe, select the menu Turbo, enter a value in the range 1-100 in the dialog box, press the OK button.  To change the speed, select the menu Turbo and enter another value.  The current speed is displayed in the main window.  The value 1-100 is the approximate percent of full speed that is available to other applications.  To stop execution, select the menu Quit.


Menus

Quit	Quit the application
Turbo	Dialog: set new Turbo Speed
Help	Display application help file (this file)


Technical Notes

Turbo works by starting a high-priority execution thread that consumes CPU time corresponding to the turbo speed that has been set.  Normal threads get only what is left over.  Real-time threads are not affected.  The execution interval is 20 milliseconds.  For example, a turbo speed of 22% means that Turbo runs 15.6 milliseconds of every 20 millisecond interval, leaving 4.4 milliseconds for other process threads to run.

Turbo has been tested on Windows 95 and Windows NT 4.0.  The consistency and accuracy for Windows 95 is less than for Windows NT.  This is because timer interrupts are not delivered as precisely (from the viewpoint of the SetTimer API).  Very small Turbo values (10% or less) will give less accurate results, i.e. the actual performance will not be exactly as specified.  The worst case, a Turbo value of 1%, results in a real slowdown to about 3-4% of full speed.