The reason one would want to disable a processor is if they are developing and want to test it for systems that do not have multiple processors.

This is important to people who are concerned about compatibility and memory efficiency.

Another specific example is if you want to play older games, such as Baldur's Gate - Shadows of Amn. which was developed for a single processor.

This has been around for awhile and it is great!

There is another way, although it is more complicated and not as safe...

Using the Mac OS X Terminal to Set the Number of Processors to One
The following instructions work for Mac OS X only. You must have the root or admin password in order to make this change. You will use the Terminal application to issue the nvram command to set the "boot-args" configuration variable. Follow these steps:

Step 1. Launch the Terminal application. The Terminal application is found at /Applications/Utilities/Terminal.

Step 2. To see the current setting of "boot-args", enter the following command:


% nvram boot-args


Step 3. Enter the following command


% sudo nvram boot-args="cpus=1"

You will need to reenter the current value of "boot-args" if you want to preserve it. For example, if the result of Step 2 was:


boot-args debug=0x4

the nvram command would read:


% sudo nvram boot-args="debug=0x4 cpus=1"


Step 4. Enter the root or administrator password when prompted.

Step 5. Restart the system.

The above command sets the "boot-args" Open Firmware configuration variable in nonvolatile RAM (NVRAM). This means that the setting is persistent across system restarts. If you decide to change the setting before restarting, a subsequent setting will overwrite a preceding setting. If you misspell "boot-args", there is no warning, a (probably useless) new entry into NVRAM is made, and the number of processors used will be unchanged after restart.


-Mac0s-