As it said it would last year (CI No 1,219), Unisys Corp has brought all the versions of the Convergent workstation operating system CTOS together under its CTOS/Open initiative. The cornerstone of this move is the first common published Application Programming Interface for all CTOS networked workstations including Unisys BTOS, Bull Starsys, Telenorma TNOS, MDS/REI and Momentum Systems Hero/OS. These operating systems (representing an installed base of 750,000) now have applications portability thanks to CTOS/Open. Christopher Isaac, CTOS marketing manager for Unisys in the UK says we call this approach 'optimised open systems' and believe that it represents an important new phase in the Open Systems movement. In fact, Unisys needs to support another operating system - a proprietary one at that - like a fish needs an umbrella. Indeed, it is widely believed that Unisys was goaded into suggesting this initiative by gossip that Bull SA was about to move in on its US CTOS market with Starsys (CI No 1,219). As it happens the Application Programming Interface is the work of the CTOS/Open Advisory Council which is sponsored by (you guessed it) Unisys and Groupe Bull. The Unisys graphical user interface for CTOS is described as consistent across both character-based and graphical workstations and is allegedly compliant with IBM's Systems Application Architecture Common User Access standard. It is built round Microsoft's Presentation Manager, and the Microsoft C Professional Development Systems v.6.0 and Pascal v.4.0 environments. Early copies of the CTOS-based Presentation Manager and the C and Pascal development environments will ship later this year, with customer shipments following in mid-1991. Presentation Manager will come bundled with an enhanced CTOS operating system. Under a second agreement, Unisys is developing a technology with XVT Software Inc to make it possible to program graphical user interface applications that are portable across, and appear as native applications on, all CTOS workstations and workstations supporting Presentation Manager, Microsoft Windows, X-Window and Macintosh windowing systems. Finally, as one might expect of a proprietary product being championed by an open systems vendor, CTOS will be Posix-compliant and is claimed to be the first non-Unix operating system to be so; unfortunately, the Posix standard as so far defined is so low-level that compliance does not mean very much.