SAN MATEO, Calif. — IBM Corp. may give a peek into Apple Computer Inc.'s 64-bit future when it details a new version of its Power4 microprocessor next week. Aimed for use in desktops and low-end servers, the 64-bit Power4 could be IBM's first PowerPC-compatible chip to support the Altivec multimedia instruction extensions defined by Apple and Motorola Inc. The IBM device is one of about 18 new processors that will be described at the Microprocessor Forum 2002, to be held Oct. 14-17. "I expect there will be a fair amount of discussion about this part," said Peter Glaskowsky, editor-in-chief...