A summary of Southern California-related business litigation developments during the past week.

Microsoft Sued by Small Firm: A Pomona-based maker of computer hardware filed an antitrust lawsuit against Microsoft Corp., charging the software giant with unfair and “outrageous” business dealings. Z-Nix Co., which makes mouse devices, accused the Redmond, Wash., company of violating antitrust laws that prohibit a company dominating one market from using its position to control another market. Z-Nix is seeking treble damages of $4.5 million on losses that it claims stem from Microsoft’s business practices. (Case No. 90-5990. Filed Nov. 7, 1990)