AppSizer interrupts the launching of your application to allow you to set the application’s MultiFinder memory partition size.  It does this when you hold down either the Control or Command key as you launch your application.  You can select which key does this in the AppSizer Control Panel.

When an application launch is interrupted, AppSizer displays a modal dialog that contains information about the memory situation on your Macintosh.  Five pieces of information are displayed: Total Installed Memory, Largest Unused Block, Suggested Memory Size, Minimum Suggested Size, and the Application’s Memory Size.

TOTAL INSTALLED MEMORY is the amount of RAM present on your Macintosh.  Under System 7, it is the amount of logical memory present.  This may be more than your physical memory if you are using virtual memory.

LARGEST UNUSED BLOCK is the amount of memory available for you to run your application in.  Your application’s memory size must be less than or equal to this number.  Warning: this number is approximate and you may sometimes have to use less than this amount.  Also, the System tends to function better if you always leave a little memory free.

SUGGESTED MEMORY SIZE is the amount of memory the creators of the application recommend for its operation.  This is often a good number to use as the application’s memory size.

MINIMUM SUGGESTED SIZE is the minimum of amount of memory the creators of the application recommend for its operation.  Using less than this amount can result in the application being unable to open documents or even bombing.

APPLICATION MEMORY SIZE is the amount of memory the application will use when it is launched.  You should set this to be somewhere between the minimum suggested and the largest unused block size.

If you do not want AppSizer to load at startup time, hold down the shift key or the mouse button and AppSizer will not install itself.  It will show a startup icon that is X-ed out to indicate that it did not load. If for any reason AppSizer encounters a problem while loading, it will also display the X-ed out icon and not load.