Toshiba Corp is investing $4.5m in Geoworks Inc, Alameda, California developer of the Geos operating system for portable computers, which comes on top of the 2.86m shares the company plans to offer. Hewlett-Packard Co and Novell Inc each made $4.5m investments in the company in March 1994, and Nokia Oy invested $7.5m in February. The investment seals a deal in which Toshiba and Geoworks will jointly develop products in the mobile communications arena, with an initial focus on the Asian market.