Just recently IBM anounced their new series of (real) mainframes. now called zServer(running zOS and zWhatever). They are supposed to be the follow up architecture of the /390 ISA and will add 64 Bit Software to the /390 world ... And here comes my problem: I can't imagine any way to enhance the /370 (/390) ISA to do such tricks at all without loosing compatibility. It would require a complete new 'mode', almost like Intel had with 16 vs 32 Bit on the 80386, Mode switching an tons of incompatibilities - it took almost 20 years to move the mainframe world from 24 to 31 Bit addressing (and 24 Bit mode is still required for some apps and modules) - and we are talking just about the valid bits of an address word (allwas 32 Bit since the 60s) - introducing new operations and data formats (or at least the usage of known but rarely supported double word size registers) is quite a different task. So what I'm searchin are informations about the new ISA. Any info is apreciated. And yes, I tried to ask IBM, (last attempt today in persona at their 'booth' at the SYSTEMS) but there is no info available. I know this is off topic, since the z900 isn't even for sale by now, but getting information is not only hard becaus IBM doen't offer it, but because the people who know what a /370 ISA is are vanishing .... so any help is apreciated. Gruss H. -- VCF Europa 2.0 am 28./29. April 2001 in Muenchen http://www.vintage.org/vcfe http://www.homecomputer.de/vcfe