Alpha Microsystems Inc has been frustrated in a whole string of acquisitions and alliances over the past couple of years, but the Santa Ana, California manufacturer of proprietary multi-user microsystems is determined to increase its volume by picking up one of its siblings. Latest target is believed to be the Business Machines arm of Rexon Inc, in nearby Culver City, California, which does some $12m a year selling its proprietary Intel iAPX-based multi-user systems. It is understood that San Francisco venture capital firm Hambrecht & Quist Inc, which has management control of Rexon, is seeking offers for the unit, and that Alpha Micro is not the only company to have expressed interest. Only the business systems arm of Rexon is for sale; the group also includes Wangtek tape drives and Tec.cw 8 mar personal computer expansion boards.