[Info-vax] Simh Licensing question 3900 vs 780

[Bob Koehler]

In article <00dbd89d$0$23376$c3e8da3 at news.astraweb.com>, JF Mezei <jfmezei.spamnot at vaxination.ca> writes:
> 
> 
> If I use SIMH in a "780" mode instead of 3900, do I lose any
> speed/functionality ? Am concerned about executables compiled for modern
> vaxes. Would they still run without problem on an emulated 780 ?

   If it runs on a VAX, it runs on a VAX, at least for user mode
   executables linked on the same or earlier versions of VMS.  The 
   emulated 11/780 may or may not have support for G and H floating 
   point operations, a real 11/780 made that optional and didn't include 
   it in the FPA, so most folks didn't buy it.  You'ld have to check the 
   SIMH documents.  If I was putting 11/780 into SIMH, I'd certainly 
   include G and H code that's already there.

   Only a few VAXen include support for the vector instructions.  I
   don't think SIMH supports those models, so there's a very good 
   chance the vector instructions aren't in there.
   
   VMS itself includes the ability to emulate G, H, vector, and other
   instructions not included in all hardware.  So if you're patient
   there's nothing you can't run.

   When support was dropped for the 11/780, it meant that VMS
   Engineering no longer tested on the 11/780, they didn't take time to
   rip out the code.  I'd not be suprized if 7.3 boots on a simulated
   11/780 and runs just fine.  I wouldn't be suprized if you could
   boot it on a real 11/780, if you can fit the VMB.EXE on the 8 1/2 inch 
   floppy.