Xemplar Education, the Acorn/Apple joint venture company, is developing a computer which will run Apple's Mac OS and Acorn's RISC OS operating systems. A StrongARM processor, the most powerful version of Acorn's original ARM chip, will be on a card which plugs into a computer based on the PowerPC reference platform, the hardware standard adopted by Apple, IBM and other makers of PowerPC systems. The system might interest Mac-using multimedia developers who plan to deliver their products on network PCs or set-top boxes running RISC OS. The machine will ship within 18 months.