🚀 go-pugleaf

Daniel Mocsny (dmocsny@minerva.che.uc.edu) writes:

>Will MIPS, SPARC, or HP-PA CPU run any binary compiled before the year
>1985? That is what I meant by "very far backwards". (See that I
>qualified my claim with "seems": I don't claim to have expertise
>here.)

PA-RISC machines with MPE XL (the HP 3000 Series 900) will run binaries
compiled in 1973 for the HP 3000 Series II, a 16-bit stack machine.  
MPE XL recognizes them and runs an emulator (called Compatibility Mode).
The performance hit is about a factor of three versus recompiling if
the program spends most of its time in user code (the system functions
have been recompiled to run natively).  There is also an object code
translator which makes (inefficient) native-mode binaries out of
"Classic 3000" binaries.  These tools were critical (and still are) for 
moving the installed base of 30,000 HP 3000s to the new architecture.

But I think IBM has more to brag about since its 3090s run 360 binaries
compiled in the 1960's (or so I've heard).  On the other hand, I believe
360 code has a hard time on System 34, System 36, System 38, the AS/400
line, and the PS/2.

Looking forward, I think the i786 (whenever it comes out) will still run 
8088 binaries.  And the Motorola 68060 will probably run 68020 code.

>Are we likely to see the fastest CPU in year X being able to run,
>without change, a binary program more than 5 years old? (Does HP-PA
>do this right now? If so, I am very impressed. I would be much more
>impressed if it could also run the large existing libraries of 
>CISC binaries at full speed, but that would be asking quite a bit :-)

The earliest PA-RISC binaries were probably compiled in 1985 and they
run native (and about 10 times faster) on the Series 700 in 1991.  That's
over five years.  Are you impressed?  :-)

-- Bill Habeck, Hewlett-Packard Company
   bhabeck@hprasor.cup.hp.com

Not a statement of HP.  No warranties.  Corrections welcome.  Etc.