Underlining the fact that VM/370 remains the poor relation in IBM’s operating system hierachy, the company only yesterday brought XA functionality for VM up to scratch – halfway through the life of the second generation of XA mainframes – but it won’t be available until April next year – March in the US, as the 3090s enter late middle age. The new VM/XA System Product Release 1 most importantly supports concurrent 31-bit and 24-bit addressing under the Conversational Monitor System, so that users can at last use the most convenient and logical approach to migrating old applications to Extended Architecture. There turns out to be plenty of hitherto unactivated microcode in the 3090E models, much of which is there to support the new VM/XA SP 1.0 release. One is extensions to the Start Interpretive Excecution Assist which enable up to four guest operating systems on a 3090E to run under VM at close to native speed. Under VM/XA SP 1, this Multiple High Performance Guests Support feature enables up to four such guests to run efficiently. Other features of VM/XA SP 1 include support for single-image working over the six-CPU 3090/600E; support for more CMS users; support for numerically- intensive functions under CMS; a new interface for development of applications that are portable between 370 and 370/XA; and support for the 3480 tape drive and 3800 printer. A second release, VM/XA SP 2, will provide support for Systems Network Architecture in an XA environment – but there is no release date given for that. The company also announced, for delivery next month, VM/ Interface Systems Facilities 2, enabling up to four mainframes to be loosely tied together under VM/High Performance Option. Release 1.8 of Resource Access Control Facility supports VM/XA SP. On the hardware front, the company has already hit the 2Gb address range limit of Extended Architecture on the 400E and 600E by doubling the maximum Expanded Storage to 2Gb; the limit on the 200E and 300E is increased to 1Gb, available second quarter 1988.