[Simh] Deathrow OpenVMS SIMH Node.. Hosted by OpenVMS?

Hittner, David T (IT) david.hittner at ngc.com
Wed Mar 11 13:58:43 EDT 2009

I'm not ruling out OpenVMS as a SIMH VAX platform. Far from it. Use it
if you want to.

Simulation of another CPU eats an astonishing number of host CPU cycles
to perform the simulation work. 

I'm trying to set your (and other's) expectation level, based on my
simulation experiences. Context is important here - maybe it's because I
already have some real VAXes, but I don't WANT another "smaller"
MicroVAX in my cluster. I already have a physical MicroVAX 4000/VLC in
my cluster, and to be frank, it's performance sucks at 5.8 VUPS,
particularly when compared to my physical MicroVAX 4000-500 at 22 VUPS.

When I ran a SIMH VAX on my Alpha PWS 500au (which runs at 155 VUPS), I
get 1.1 VUPS on the SIMH VAX. For comparison, when I ran the SIMH VAX on
my 3.0 GHz PC, it simulated 1.89 VUPS.

If you have newer iron like the multi-issue Alpha ESxx/GSxx servers (or
even a DS10!!) just sitting around that you can run simulations on, go
for it. If you are looking at _purchasing_ a low-cost platform for home
use to run VAX software, I'm merely suggesting that you might want to
take the cheaper path to Hobbyist VAX performance, which is a fast PC
running SIMH VAX - or many times, just a used VAX.

I'd be happy to look at your Alpha-based SIMH VAX VUPS numbers for
comparison with mine; maybe my measuring and estimating sucks. :-))

FWIW, my low-end HP Integrity rx2620 [at work] running OpenVMS clocks in
at 533 VUPS. I've never tried running SIMH it, but I'm sure it would be
much better than the Alpha (at 155 VUPS); but then again, just try to
buy an rx2620 on Ebay ... $$$. The semi-affordable, semi-supported
rx2600 is pretty reasonable on Ebay at $300-$2500, but is _much_ slower
than the rx2620.


> -----Original Message-----

> From: Bill Korendyk [mailto:bill at korendyk.net] 
> Sent: Wednesday, March 11, 2009 12:14 PM
> To: Hittner, David T (IS); simh at trailing-edge.com
> Subject: RE: [Simh] Deathrow OpenVMS SIMH Node.. Hosted by OpenVMS?
> Hi Dave,
> Thanks for your response.
> On Tue, 10 Mar 2009 13:13:06 -0500 "Hittner, David T (IT)" 
> <david.hittner at ngc.com> wrote:
> > Bill,
> > 
> > The reason you don't see any networking under OpenVMS Alpha 
> is likely 
> > because you didn't install the VMS PCAP Execlet. I didn't see any 
> > reference to you doing so in the message below.
> I believe the Execlet was installed; if I recall correctly, 
> the behaviour and errors were very different before it was installed.
> I'll check the next time I have a chance to work on this. In 
> the meantime, additional hints are welcome ;-)
> > Regarding running SIMH VAX on OpenVMS Alpha: that would be a gross 
> > waste of the Alpha unless it had absolutely nothing else to do. The 
> > performance of SIMH on a recent PC will decimate SIMH 
> performance on 
> > OpenVMS Alpha. Same for any Itegrity machines that you or I 
> can afford.
> > :-)
> Hmm. I fear he doth exaggerate slightly :-)
> > All Alphas were excellent then, but the lower-end ones are somewhat 
> > slow now compared to high-end PCs. Higher-end 
> Alpha/Integrity machines 
> > might perform better, but still - SIMH really chews up 
> single-stream 
> > CPU cycles, and a PC is much cheaper.
> Yes, newer boxes are faster (and cheaper). But I already have 
> the Alpha and wanted to avoid building and configuring (yet) 
> another box needing care and attention, and adding to the power bill.
> And since my "old" PCs are "really" old, buying a new PC for 
> this task seemed silly with a perfectly good Alpha to use. 
> SimH/VAX works fine (albeit off the network) and my 
> benchmarks show it running as well as a smaller MicroVAX. 
> So I find the SimH/VAX hosted on OpenVMS is adequate, 
> especially for a hobbyist environment. Saves time and money, 
> runs solid, responds well, and the process (unless very 
> CPU-intensive) is barely noticed (i.e. buried in all the 
> other activity) on my lowly DS10 ;-)  I'd sure like to try it 
> on an Integrity...
> So, let's not offhand rule out OpenVMS as a SimH host shall we :-)
> \bill
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>      Bill Korendyk      Bill at korendyk.net    "Just call me Bill."
> --------------------------------------------------------------------
>          "Where am I going... and why am I in a handbasket?"
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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