IBM Corp is now planning to announce Windows NT for the System/390 mainframe on Tuesday – and has gone down to the wire and then pulled the announcement four times already, IBM System User hears. It appears that the facility, expected to be available in the fourth quarter, is more a means of running Windows NT applications on the mainframe than a full-blown implementation of the operating system – it apparently runs not on a co-processor, or in a Logical Partition but as a personality for MVS. NT applications will need to be recompiled and tuned. The native IBM operating system traps all the system calls because, IBM claims, native Windows NT imposes an unexpectedly high overhead, which is minimized by having MVS do the real work. Basis of the implementation is thought to be the Wind/U version of Windows NT for Unix from Bristol Technology Corp, moved across from Unix and adapted to run over MVS. Bristol Technology, of Bridgefield, Connecticut, is one of only four companies to which Microsoft Corp has deigned to license the generality of its Windows and Windows NT source code.
