[Simh] Compatibility you can use Was: VAX/VMS

[Johnny Billquist]

On 2016-02-22 07:07, lists at openmailbox.org wrote:
> On Sun, 21 Feb 2016 08:50:45 -0500
> Clem Cole <clemc at ccc.com> 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.

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. And the OS 
should detect that it's a 32-bit application, and set the system up for 
running such an application with the CPU set the right way. The CPU can 
do it. If things fail because the OS does things wrong, you should not 
blame the CPU.

> 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.

I think you are confusing the backware compatibility in the processor, 
which is working just fine, with the less than stellar backward 
compatibility in various OSes along the way, which is nothing you should 
blame on Intel.

Like I said, grab an old DOS floppy, pop it into a a new machine, and it 
will boot. That's a fact.

> 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.

Yes. IBM has done an excellent job.

	Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol