> > > > You can't seriously mean that you think that a 32-bit application and > > a 64-bit application would be expected to be compatible with each other? > > I would expect the 32-bit code to work in 32-bit mode, but having it > > work if you are in 64-bit mode is a ridiculous expectation. > > Really? It works fine on IBM's z/OS. > > It seems ridiculous to me that you think it shouldn't. This is what I have > been > saying. IBM moved from 24 bit to 31 bit to 64 bit and everything still works. > No expanded footprint, no duplicate libraries, no problem. >
That’s not (quite) true. As I said before problem state code works fine. Anything that uses supervisor mode will likely fail. It took IBM a lot of work, microcode (SIE instruction) and a new Hypervisor to get from MVS/SP to MVS/XA. I am told VM/XA only exits because they needed it to debug MVS/XA. There is much more I info about IBM and especially VM's history on Melinda Varian's home page:- http://www.leeandmelindavarian.com/Melinda/ and as for backwards compatibility the book "The soul of a new machine" http://www.amazon.co.uk/The-Soul-Machine-Modern-Library/dp/0679602615 has some interesting observations about building a new machine... Dave G4UGM _______________________________________________ Simh mailing list Simh@trailing-edge.com http://mailman.trailing-edge.com/mailman/listinfo/simh
