How do I optimise memory in Mac OS 9 for use with Openlab?

Technical Note: 97
Reads: 6524
Creation Date: 11/04/2000
Modification Date: 19/08/2005

How much memory is installed in your computer?

To check the amount of memory installed in your computer, you need to make sure that you are in the finder (ie. click on the Desktop) and that you have quit Openlab. Go to the "Apple" menu in the top left hand corner of the screen, select "About This Computer". This will display a dialogue which will tell you the amount of "Built-in Memory" and the "Largest Unused Block".

Memory requirements (for all versions of Openlab)

You should assign to Openlab approximately 85 - 90% of the amount of memory shown in the "Largest Unused Block". Do not allocate all of the available memory to Openlab as this may cause the Finder to operate incorrectly.

To change the memory allocation to Openlab, find and select the Openlab program icon (not the Openlab alias icon). Press "Apple"and "i" together, and in the window which appears, select "Memory" from the "Show" pop-up menu. The amount of memory which is currently allocated to Openlab is shown in "Preferred Size". Change this figure to match 80 – 85% of the "Largest Unused Block". Note that as with all memory re-allocation , you must quit the application and restart the computer to invoke the change.

Openlab was introduced with Mac OS 7.5, we recommend the latest operating system available for use with currently available versions of Openlab. At present this is Mac OS 9.2.2. Note that the later versions of Mac OS require more RAM for their functionality, so check the overall system memory usage when you install an updated OS.

Mac OS X

Mac OS X has a completely different memory management system. It is not necessary to assign memory to applications or be concerned about virtual memory. Openlab 3.1 and higher will run on Mac OS X. Please see TN355 for more information.