Posing a potentially devastating threat to the rapid take-up of IBM and Microsoft’s Presentation Manager user interface for the OS/2 operating system, Apple Computer Inc launched lawsuits against Hewlett-Packard Co and Microsoft Corp late last week, alleging that Hewlett’s NewWave and Microsoft’s Windows release 2.03 infringe Apple’s copyright in the look and feel of the Apple Macintosh user interface. The Presentation Manager, due to be available towards the end of the year, is the OS/2 extension seen as the principal attraction of the operating system and the key to its widespread acceptance. Presentation Manager is not mentioned in Apple’s suit, but since the product is not yet on the market, it is too early for Apple to complain of damage to its interests. Apple was tightlipped on whether it would launch a suit over Presentation Manager, saying simply that it intends to protect its interests, but the timing of the suit against the other two products seems calculated to inflict the maximum damage on the commercial success of Presentation Manager, coming as it does at a time when software developers are weighing up whether or not to invest in applications that use the interface. The suit contends that Hewlett’s NewWave embodies what it calls the Macint osh audio visual display and that Microsoft’s Windows 2.03 is necess ary for New Wave to operate. Apple believes Hewlett Packard received a licence from Microsoft for the use of Windows 2.03 in NewWave, and its suit contends that the screen disp lays generated by Windows 2.03 are themselves illegal copies of the Macintosh audio visual works and exceed the limited licence rights Apple has granted to Microsoft.