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RAM Footprint

The NewWorld architecture puts the Mac OS ROM Image in RAM, and marks it read-only. Although the image is 4 megabytes in size, not all of it is in use. The portion that is not used is returned to the Mac OS for use as part of system RAM. At the time this document was written, less than 3 megabytes of the 4 megabyte Mac OS ROM Image are in use, allowing more than 1 megabyte to be returned to the Mac OS.