FEEDBACK from testing of Microsoft's Windows NT operating system Beta I has shown Microsoft that its customers are taking the compatibility and connectivity of Microsoft Windows NT for granted. ''They know that Microsoft will get connectivity right, and that it will be a truly open system - because it will become the industry standard. ''What customers are asking about is the power,'' said Microsoft country manager Mr Laurie Kan. When Windows NT is released (scheduled for the middle of this year), it will support three applications environments: MS DOS, 16-bit and 32-bit Windows applications; IBM's OS/2 text-based operating system; and basic POSIX stream I/O applications. Anyone who has invested in these environments should be able to use Windows NT and its applications without changing a single line of code. So far, UNIX-based hardware vendors HP and Digital are working on versions of Windows NT to run on their reduced-instruction-set-computing-based (RISC-based) workstations. DOS-based Intel and UNIX-based MIPS have already developed versions of NT to run on their workstations and it is the MIPS Beta II version that is now being test-run by about 35,000 Microsoft users whose responses will be considered by Microsoft. A further 35,000 Beta 1 versions have already been tested, and responses as to scalability, expansion, security and connectivity have been considered for modifications since made to Beta II. Microsoft believes development by these major four vendors will mean Windows NT will cover more than 90 per cent of the workstation market. About 250 major software vendors which, including, in Microsoft's view, all the key companies, are now developing Windows NT applications with WIN 2, Microsoft's new Application Programming Interface. Microsoft expects these yet-to-be-developed applications will run on Windows NT on any desktops, workstations or minis, regardless of what operating system the hardware used to run on. A total of 55,000 Software Development Keys of source information for software development have been sold to all levels of the development market. ''With WIN32, developers will make the most of any hardware, so that Windows NT will become a true industry standard,'' said Mr David Chung, Microsoft product support and services engineer. ''WIN32 is very important because it enables development of client or server applications or both. ''Previously, everyone had to develop UNIX applications under a UNIX API. ''Now, with WIN32, there is a new interface to develop on, based on the new operating system, Windows NT,'' Mr Chung said. Because WIN32 is an extension of WIN16, Microsoft expects applications development on WIN32 will be easy, even without retraining. ''With HP, Digital, MIPS, and Intel developing their versions of Windows NT, we have covered more than half the RISC-based machines on the market. ''At this stage, the only two big vendors left out are Sun Microsystems and IBM.'' Wider support of industry standards by Windows NT depends on the time-frame and the priority Microsoft puts on different operating systems. The company believes it has fulfilled what it claimed it would for the first version of Windows NT. Customer demand for new features such as further IBM OS/2 support (for example, of OS/2 Presentation Manager support) or further POSIX support, or a move up to B2 security are likely enhancements for future versions. Mr Kan thought it ridiculous that Microsoft had been criticised for excluding some vendors from playing the Windows NT game. ''We're not trying to shake other companies out of the industry. We want to take an evolutionary approach, which is easier for training and migration to Windows NT,'' Mr Kan said. ''Companies have to demonstrate that they seriously want to develop products on the Windows NT platform. ''And, of course, there are companies such as IBM, Novell and Sun Microsystems which don't want to get involved because they have competing products,'' Mr Kan said. He expected Windows NT would be hitting the workstation market hard because the new operating system would force vendors to speed up development of better hardware and software applications technology at a lower price. ''The customer who has previously been limited to UNIX and limited only to expensive workstations such as Sun's will find that a cheaper PC - for example, Intel-based - will suddenly be used for industrial 'mission-critical' applications that used to be handled only by expensive hardware,'' he said. The power for multi-tasking, in-built networking communications, and better memory and speed - crucial for winning over industrial users - is available on Windows NT, which will support both 16-bit and 32-bit Windows applications. When Digital's version is available on its 64-bit Alpha processor, Microsoft claims there will be virtually no industrial applications that cannot be handled by the Windows NT-Alpha combination. Mr Kan said COSE, the Common Open Systems Environment group - which includes IBM, Sun Microsystems, Novell and USL, HP, and SCO - did not worry Microsoft. ''It seems that every few years, UNIX vendors get together to placate customers' worries about the way products run on too many different versions of UNIX. ''This time, the group is not as big. It does not include Digital, NCR nor ICL, as similar groups have in the past, so I don't think it will be such a successful group,'' he said.