French start-up Machine Independent Software SA, the cross-system software development subsidiary of the $25m-a-year Sun Microsystems Inc integrator Diva SA, has developed a portable implementation of the Microsoft Corp Windows application programming interface that will enable Windows applications to run on Solaris, UnixWare, AIX, HP-UX, VMS and OSF/1 boxes after recompilation. The software is a new head-to-head competitor for the offerings from the likes of Insignia Solutions Inc, Praxsys, now owned by SunSelect, and Bristol Technology Inc. Reportedly others are on the way. MainSoft, as the company styles itself, expects to begin delivering the product, known as MainWin 3.0, in the US next month. It says MainWin can run on any Posix-compliant X Window-based operating system and it intends to start with Solaris 1.0 and 2.1, AIX, UnixWare and HP-UX. With MainWin, the Windows applications are claimed to run in native mode with no intervening emulation level to slow down performance. In fact, the company claims that when running on a Unix workstation, MainWin’s graphics performance (its Windows display, scroll bars and menus) is the equivalent of Windows running on an Intel Corp 80486 box. Application developers however, need to maintain only a single version of their source code for all systems. Currently MainWin can handle only Windows 3.0 programs with 3.1 support expected in the second half. The programs must also be written in portable ANSI C. If so, developers only have to make slight modifications such as adding include lines and converting file names before compiling and running the application on the target system. With MainWin, the application will run in its native environment such as Open Look or Motif and have the Windows look and feel. The company says the software offers most of 600 Windows calls. It does not include segmented memory management calls that are not useful on 32-bit systems. MainSoft, which intends to branch off into development environments and generic tools over the next 12 months, started shipping the product in Europe in December. It is opening an office in San Francisco, which will be run by founder and president Jacques Quelene. It will strut its stuff at the Software Development conference in Santa Clara, California this month. Development kits will go for $5,000 with run-time licences separately priced.