US reports say that Apple Computer Inc intends to try to raise interest in the PowerPC microprocessor it has co-developed with IBM Corp and Motorola Inc by licensing its Macintosh System 7 operating system to other personal computer manufacturers interested in using the chip. Apple is said to have already offered System 7 to such MS-DOS and Windows devotees as Dell Computer Corp and Gateway 2000 Inc. Both firms declined to comment. Until now, Apple has indicated that other vendors will be able to run Macintosh software only in an emulation window under the PowerOpen Unix environment, which should be available by the middle of 1994. Earlier this year, it also came to light that Apple engineers are experimenting with a modified version of System 7.1 that would run on Intel Corp 80486-based machines, using Microsoft Corp’s MS-DOS.