[Info-vax] Prices of Microvax 3100's

[Paul Sture]

On Thu, 03 May 2012 13:45:41 -0700, John Wallace wrote:

> On May 3, 2:59 pm, koeh... at eisner.nospam.encompasserve.org (Bob Koehler)
> wrote:
>> In article
>> <0c85168b-2bb2-413c-b27a-214935e8d... at w7g2000vbg.googlegroups.com>, AEF
>> <spamsink2... at yahoo.com> writes:
>>
>>
>>
>> > So why not run Charon or SIMH? Speaking of which -- and please pardon
>> > me if this is a stupid question -- do these things run as a separate
>> > process or do they take over the entire machine? I don't see why it
>> > can't be the former. Just making sure.
>>
>>    SIMH is just an ordinary application as far as I've seen.  It can
>>    be a significant CPU load, but I've been able to timeshare with it
>>    on all the desktop OS I've tried it with.
> 
> SIMH can be greedy, as can others, but the main issue with coexistence
> is likely not the behaviours of the VMS-hosting emulator application,
> but the behaviour of Windows and Windows-based applications on Windows
> systems, and in in particular the impact of any undesirable behaviour on
> VMS and the applications in the VMS environment. (I hope that sentence
> made sense).

The problem with SIMH of several years ago was that the VMS idle loop 
would use 98% or so of the host processor and the fans would kick in.

As I recently reported here, the latest Release Candidate of SIMH using 
the "set cpu idle[=vms]" option will take 10% or less of the host's CPU 
when VMS is not doing any work.  Obviously, throw some CPU intensive work 
at VMS, and it will take the host processor up to 90% or more.
 
> That's why from time to time you see people round here asking about
> Linux versions of the emulators and why at least one of the emulators
> has a version that runs on QNX, the realtime OS. If the host OS has to
> be Windows then it's presumably safest to treat the Window box as a
> single purpose box but that isn't really much of a guarantee of good
> behaviour, especially in the presence of the stuff usually associated
> with a Window box of any kind.

Another problem is with "Patch Tuesday".  Obviously those responsible for 
the health of the Windows systems want to make sure they are all up to 
date with patches, but you as the manager of a VMS system want to avoid 
unnecessary downtime.  You almost certainly don't want Windows to do the 
automatic update complete with reboot at 3am, which is the "recommended 
option" (yeah, and by default it nags you to change to that 
recommendation if you have it set otherwise).

The other problem is the sheer length of time it can take to apply some 
Windows patches. April's Patch Tuesday brought me some .NET patches which 
seemed to take an eternity to apply on some systems here, but were 
relatively painless on others.

If your host is Windows Server rather than Windows 7, the patches aren't 
confined to Patch Tuesday either, at least in my experience.

-- 
Paul Sture