On Sun, 21 Feb 2016 08:50:45 -0500 Clem Cole <[email protected]> wrote: > To pick on DEC (or IBM), the later generations of their respective ISAs > cannot boot the older OS – which Intel’s primary ISA can – and that is > what started this discussion.
I can't speak to DEC's issues but with IBM has already been said, this was by design. They were selling hardware. The OS and program products helped them do that. However, we see that Intel's hardware compatability is only of academic interest because virtually none of the OS or apps for several generations of Intel chips runs on any remotely current Intel-hosted OS. I already pointed out many day-to-day incompatibilities between code running 32 bit vs. 64 etc. on Intel today. You can blame Microsoft or Bell Labs or even Richard Stallman but Intel has certainly been involved intimately with much OS development on its platform and has continued to bork time after time. We all know at the end of the day people buy hardware to run apps. We also know most of the apps ever written for Intel are no longer useful even if you could boot obsolete OS and run them. Any meaningful notion of compatibility has to include the ability to continue to run your apps on every new OS and hardware generation. With Intel you can't. You can point all the fingers you want but that is the reality in the Intel environment. In practice, several decades of software and development investment, applications, and OS go up in smoke with each new generation of Intel chips. In contrast IBM has preserved the customer's investments in technology, development, and applications. IBM takes the loss on the OS development but the customer's applications continue to run forever on the latest platform. Intel is an ecosystem of churning, turmoil and waste. That's something only an accountant could love. As has been noted code from virtually the beginning of OS/360 still runs today and furthermore can happily coexist with newly written apps without any hoop jumping like relinking, recompiling, or needing multiple libraries. It just continues to work. Software compatibility beats hardware compatibility any day of the week. What's important is that your application and development investment continues to be viable on each new hardware platform with each new OS. That is what IBM has done, and it is a combination of hardware and software designed to work together and boy does it ever, as opposed to a pizza with everything on it spoiled by too many chefs. In terms of rubber meets the road upward compatibility what IBM has delivered over the lifetime of OS/360->MVS-XA-ESA-z is infinitely more valuable than compatibility on paper that nobody who runs Intel has ever been able to take any practical advantage of. _______________________________________________ Simh mailing list [email protected] http://mailman.trailing-edge.com/mailman/listinfo/simh
