With Mac OS 9 and earlier, the Clipboard uses an application program's available memory. Therefore, you cannot copy data to the Clipboard that uses more memory than is available within the application.

When data is copied to the Clipboard, the information is stored within the application program's memory partition. An "out of memory" message when copying data to the Clipboard indicates that there is not enough memory available in the application's memory partition to perform the operation. Consider this simple example:

An application has been assigned a 5 MB memory partition, and uses 2 MB to open and operate. Therefore, 3 MB remains available for data and documents. If a document is opened that uses 2 MB of the application's available memory, then 1 MB is all that is available for use by the Clipboard. Attempting to copy more than 1 MB of data to the Clipboard while using this application results in an "out of memory" error message.

Follow these steps to see how Clipboard usage affects an application's memory:

1. Open your application.

2. Open a document with a large amount of data (a complex image, or a lengthy text passage, or a video clip).

3. Choose Finder from the Application menu.

4. Choose About This Computer from the Apple menu (see Figure 1). Position this window so that it is still visible when using your application.




Figure 1 About This Computer

5. Notice the memory usage bar for your application program. The filled-in portion of the bar represents the amount of memory currently being used by the application. (Choose Show Balloons from the Help menu, then point to the memory usage bar for an exact number.)

6. Choose your application from the Application menu.

7. Select a large amount of data in the document that you have opened.

8. Choose Copy from the Edit menu of your application. Notice how the memory bar changes; the Clipboard is using the application's memory to perform the operation.