Systems and Technologies

Increase the application preferred memory size

In classic Mac OS (but not Mac OS X), you may need to increase the amount of memory allocated to a program. This can sometimes fix problems when running the program or improve performance when you have more memory installed in the computer.

Mac OS 9 office systems at RIT, for example, typically had 32-128 MB of memory installed. However, many programs would not make use of all the available memory unless you modified their settings slightly. (Mac OS X automatically allocates memory for each application as needed.)

Note: You should only increase the memory allowance for an application if you are getting "out of memory" or "not enough memory" errors when you run it. Increasing the memory allocation is not a cure-all and will not solve every application problem on classic Mac OS.

To increase the amount of memory alloted a program:

  1. Quit the application so that it is no longer running. (Generally, use File menu > Quit.)
    Note: You cannot change the amount of memory assigned to a program while the program is running.
  2. Find the program's icon in the Finder.
  3. Click once on the program's icon to highlight it.
  4. Select File menu > Get Info.
    9GetInfoGeneral: Mac OS's Get Info window, showing general information
  5. Choose "Memory" from the "Show" pop-up menu in the "Get Info" window.
    9GetInfoMemory: Mac OS 9's Get Info window, showing an application's memory information
  6. Type a higher number in the "Preferred Size" field.
    Note: Start by doubling the "Preferred Size." If doubling this figure doesn't resolve your memory-related problem with the application, there may be other problems that simply changing the memory allocation won't solve.
    Note: Do not change the "Minimum Size" field. This sets how much memory the application will use at the minimum; increasing may actually create problems. The "Preferred Size" field provides the upper limit and is therefore safer to change.
  7. Close the "Get Info" window to save the changes.
  8. Re-launch the application. If you were having a memory-related problem, determine whether it persists.
Section: Use a Macintosh
Keywords: applications, error, mac os 8, mac os 9, system administration, troubleshooting
Question: How do I increase the amount of memory a program is able to use in classic Mac OS?
FAQ item: true
Score: 750