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Re: Switching Over to New System

 
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James LaRue
Advisor

Switching Over to New System

How hard would it be to move an old VAX 3100 system and a VAX 4000 system over to the newer Alpha systems? Will the old VMS software run on the newer OpenVMS without any problems?
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Volker Halle
Honored Contributor
Solution

Re: Switching Over to New System

James,

welcome to the OpenVMS ITRC forum !

OpenVMS Alpha runs on the Alpha processor, whereas OpenVMS VAX runs on the VAX processor. Both have different HW architectures and instruction sets.

You would need to install the OpenVMS Alpha operating system. All your application .EXE files would typically need to be re-compiled (from source) and re-linked, although there is also a binary translator (called DECmigrate or VEST), which can translate VAX instruction in .EXE files into Alpha instructions at a noticable performance loss.

May I also point out the possibilty to run OpenVMS VAX operating systems and programs using the CHARON-VAX emulator (commercial product) or simh (freeware) ? This is a software emulation of the VAX hardware machine and runs on various host operating systems (e.g. Windows, OpenVMS Alpha and Itanium, Linux). You must see it, to believe that it works, but it does !

Volker.
Steven Schweda
Honored Contributor

Re: Switching Over to New System

It depends on too many things to give an
answer with so little information.

DCL command procedures will probably work.

All compiled programs would need to be
recompiled, as the VAX and Alpha instruction
sets differ. Some (most?) code works with no
changes; some needs serious effort to get it
to work.

Some HP and third-party software may be
unavailable.

Some specialized hardware may cause extra
difficulties.

There are some migration-related documents
available at:

http://h71000.www7.hp.com/doc/archived.html

Migrating an Application from OpenVMS VAX to OpenVMS Alpha

Migrating an Environment from OpenVMS VAX to OpenVMS Alpha

Migrating to an OpenVMS AXP System: Recompiling and Relinking Applications

Migrating to an OpenVMS AXP System: Planning for Migration

The fact that they're included on a page
named "archived.html" suggests that you're
not the first person to try this.

You might also skip straight to Itanium, but
almost any work you need to move to Alpha
would be useful for a later move to Itanium.
James LaRue
Advisor

Re: Switching Over to New System

Thanks Volkre for your response.

My main question is that I have a program that is very very important that runs on the VMS operating system that I would like to be able to work on the newer hardware as I really really need to upgrade. But I am scared that there will be a lot of software reworking to get it to work. But if there is a way to get it to work without rewriting the software completely then that would be great too. Cause in reality this upgrade is just for hardware support as the current system has been working wonderfully for 20 years.
Steven Schweda
Honored Contributor

Re: Switching Over to New System

> All compiled programs would need to be
recompiled

Oops. I completely forgot about VEST.
James LaRue
Advisor

Re: Switching Over to New System

Steven,

thanks for the response.

this system is vms not openvms...it is really old I think version 5.5 or something like that. I have everything written down but I am not where the information is. Basically it is a 32 bit program..so i figure it wont be transferable to the newer 64 bit system.
Volker Halle
Honored Contributor

Re: Switching Over to New System

James,

if this is an important application for you, I definitely would suggest the CHARON-VAX emulator. Depending on your current HW config, you may not need to change ANYTHING from the application and OpenVMS VAX perspective, if you can emulate all your hardware devices using CHARON-VAX.

I would suggest, that you try to find a CHARON-VAX reseller near you. Try

http://www.softresint.com/charon-vax/index.htm

Volker.
Steven Schweda
Honored Contributor

Re: Switching Over to New System

If you would like to experiment on an Alpha
(or Itanium) system at no cost, there are HP
TestDrive systems available. You could FTP
your application kit to one of the TestDrive
machines, and see how difficult it is to
build. Depending on resource requirements,
serious testing may be more difficult, but
it could be a very educational exercise.

http://www.testdrive.hp.com/

Whenever I move some VMS software to a
different hardware platform, I'm always
amazed at how much stuff just works.
Steven Schweda
Honored Contributor

Re: Switching Over to New System

> this system is vms not openvms

Them's fightin' words...

You need to read the [Open]VMS FAQ:

http://h71000.www7.hp.com/faq/openvms_faq.html

2.2 What is the difference between VMS and OpenVMS?

VMS and OpenVMS are two names for the same
operating system. [...]


See? It's already an educational experience,
and you've hardly started.

I've built and run the Info-ZIP Zip and UnZip
programs run on systems from VMS VAX V5.4 to
Itanium V8.2-1, so age by itself is no
guarantee of trouble. (There are some "#if"
directives in the code, of course, but not
so very many, I'd say.) You can assume that
some changes will be needed, but the number
and scope are tough to predict.
Ian Miller.
Honored Contributor

Re: Switching Over to New System

Read the migration documents previously mentioned. See also
http://h71000.www7.hp.com/openvms/integrity/transition/index.html
http://h71000.www7.hp.com/openvms/integrity/resources.html

It depends on the system. If it is really a unchanging application then do look at the emulated VAX option. If the application is likely to be changed in the future then do consider porting to OpenVMS Itanium. This can be remarkably straigtforward or it can be a lot of work but this very much depends on the application.

There are a multitude of considerations - you may wish to find yourself a consultant who has done this before.
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