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dd of vax boot tape

S Zack
Occasional Visitor

dd of vax boot tape

Hello,

Does anybody know how to create dd image of the boot tape I made with backup utility?

Thank you.
11 REPLIES
Steven Schweda
Honored Contributor

Re: dd of vax boot tape

What's a "boot tape"?

> [...] made with backup utility [...]

How, exactly?

Did you wish to do this on a non-VMS system
using "dd", or on a VMS system somehow? Why?
Is there some actual problem which you are
trying to solve?
S Zack
Occasional Visitor

Re: dd of vax boot tape

I made it with STABACKIT utility. Want to try to boot it under simh emulator, so I need a file image of it.
Steven Schweda
Honored Contributor

Re: dd of vax boot tape

> Did you wish to do this on a non-VMS system
> using "dd", or on a VMS system somehow?

This still matters.

I use real VAXes, not emulators, and I
haven't installed any VMS on one for years,
but I'd guess that it'd be easier to start
with something on a (real or emulated) disk
than something on a real tape. I doubt that
the stuff on a Standalone BACKUP tape is the
same as the stuff on a Standalone BACKUP disk
installation, so I doubt that you can boot
off an emulated disk which contains an image
of what's on a (real) tape. (My doubt is
not proof, however.)

Someone who actually does deal with an
emulator may actually know something. I'll
bet that Google could find some info on
booting SAB on a VAX emulator.
S Zack
Occasional Visitor

Re: dd of vax boot tape

I beleive it's still possible. Please see section 2.6 in the http://simh.trailing-edge.com/pdf/simh_faq.pdf
Steven Schweda
Honored Contributor

Re: dd of vax boot tape

> I beleive it's still possible. [...]

Ok. Possible and easy are spelled
differently for a good reason, however.

> > Did you wish to do this on a non-VMS system
> > using "dd", or on a VMS system somehow?
>
> This still matters.

After three tries I stop asking.
DECxchange
Regular Advisor

Re: dd of vax boot tape

I'm not sure exactly what you're asking, but if you're asking how to make a standalone backup on a disk drive under VMS, you must be talking about VAX-VMS, because Alpha does not have Standalone Backup.

To make a standalone backup on a VAX disc drive, you simply to a:

@sys$manager:stabackit

or sys$system, I don't have the VAX in front of me right now.

Then stabackit prompts you with the device name, either tape or disc. Just put the device name in.

I don't think there's a way to create a disc version of Stabackit from a tape. You have to do it from the VMS operating system. Stabackit is only for doing standalone backups, either from disc to tape, tape to disc, or disc to disc. It has no other purpose or capability.

If I presumed your question wrong, then what do you mean by "dd" and what you mean by "boot tape" and exactly what backup utility command with switches did you use?

Thanks.
Volker Halle
Honored Contributor

Re: dd of vax boot tape

S,

welcome to the OpenVMS ITRC forum.

If I understand your question correctly, you have a real VAX with a real tape and you've created a bootable tape using @STABACKIT.

You now want to boot simh from that 'tape', but you don't have a compatible physical tape connected to the system where you're running simh on. So you want to create a 'virtual tape' file from the contents of that physical tape and boot simh with something like >>> B MUA0 where MUA0 points to a virtual tape file.

Assuming simh supports virtual tapes, you need some system which both has a physical tape connected and supports creating a virtual tape file in the correct format for simh to understand.

The CHARON-VAX product provides the MTD utility, which runs on Windows and can copy data from a physical tape to a .MTD (or .VTAPE) virtual tape file. Whether simh would be able to read that virtual tape file, I can't tell.

How about running simh on your VAX, configure a virtual tape and then run @STABACKIT to create a standalone backup on that virtual tape ? This should do what you want.

Volker.
Bojan Nemec
Honored Contributor

Re: dd of vax boot tape

Zack,

Simh uses a special format for virtual tape files. There are some tools for converting to this format (download the simtools.zip file
http://simh.trailing-edge.com/sources/simtools.zip
).
A quick look to the utilities give me the mtcvtv32 utility which converts from UNIX dump format to simh format. The specification of the UNIX dump format looks yust like the VMS variable length sequential file.
So you can try (on VMS) to mount foreign the tape and copy the files to the disk (there should be more than one file on the tape including ANSI tape headers, but now I have no VAX under my hands to check the structure of the boot tape). Examine each file and convert it to a variable length sequential file (use the VMS CONVERT utility with a simple fdl with RECORD FORMAT VARIABLE).
Transfer the files to the simh sistem (binary !) and use the mtcvtv32 utility to create the virtual tape.

I have not tested this procedure so its on you to try it.

Bojan
Verne Britton
Regular Advisor

Re: dd of vax boot tape

If you want to test SIMH, try using the LD utility to create a small container file on your VAX, then build the disk version of STABACKIT on that LD device, then dismount and copy the LD container file to your SIMH machine and boot from it ...

just a thought; I have no SIMH experience at all :-)

Verne
Willem Grooters
Honored Contributor

Re: dd of vax boot tape

In addition to the last entry: Once you have created the diskcontainer, get it as-is (so FTP in binary format) to Windows or Linux, and burn it - as-is - to CD.

Willem
Willem Grooters
OpenVMS Developer & System Manager
John B Pierce
Occasional Visitor

Re: dd of vax boot tape

The following program will read a tape into SIMH tap-format on linux.

http://inwap.com/pdp10/usenet/timage.c

You would need to be using unix (suggested by dd anyways) and be able to attach the magtape drive (hopefully SCSI) to the unix machine. The tap-formatted output file can then be booted by the simulator.