[Simh] Simh Digest, Vol 166, Issue 12
Peter Allan
petermallan at gmail.com
Tue Nov 7 15:54:31 EST 2017
In order to try to understand why I am having trouble reading a simulated
tape with a simulated TE16 tape drive on a simh VAX 780, I have tried
several configurations.
Firstly, a point of clarification. The problem that I came across was in
finishing the installation of VMS 3.0. This was necessary in order to be
able to install VMS 1.5 using DSC2, but I have no problem with the
installation of VMS 1.5 itself. VMS 1.5 is a red herring - the problem is
with VMS 3.0.
I had configured a VAX 780 in simh with three RP06 disk drives and two TE16
tape drives. I was using TE16 tape drives rather than TS11 really just
because when I was the system manager of a real 780, it had two TE16 tape
drives.
All of this has been done on a host system running CentOS 5 (for simh
3.8-1) and CentOS 6 (for simh 4.0).
To remind you of the problem, I started the installation of VMS 3.0 by
booting stand-alone backup and restoring a saveset from a tape that I
downloaded from the University of Stuttgart. The first phase went fine and
when I rebooted the 780, the system asked which device contained the
installation media so that it could automatically complete the installation
of VMS. I entered MTA0: and this is where things went wrong. Wilm suggested
I should trying using a TS11 drive (MSA0) rather than a TE16 drive and this
did indeed work, but this left me wondering why?
I have tried to restore a BACKUP saveset from a tape to a disk using
several configurations. I have tried:
- Two difference versions of simh, 3.8-1 and 4.0
- Three different versions of VMS, 3.0, 4.6 and 7.3
- Different simulated tapes
- The two different simulated tape drives, TS11 and TE16
The results have surprised me.
1) Changing the version of simh makes no difference to the results.
2) I only get a problem in restoring a saveset from tape when running
VMS 3.0 as the operating system. Everything works fine with VMS 4.6 and 7.3.
3) I have tried different tapes, but if the system is going to fail to
do a restore operation, it does it with all of the tapes containing BACKUP
savesets that I tried.
Following a suggestion from Kevin Handy, I tried to copy the savesets from
tape to disk, but the copy failed on the VMS 3.0 system when using a TE16
tape drive.
My experiments indicate that there is a problem with VMS 3.0 when using
TE16 tape drives. However, this seems so unlikely, not least because the
sequence of operations that I have gone through is what hundreds (thousands
probably) of system managers must have done to install VMS 3.0 on real
hardware, including my predecessor with “my own” 780.
This leaves me stumped, but at least I have narrowed the problem down and I
am able to do the installation of VMS 3.0 (which lets me do the
installation of 1.5) by using a TS11 drive.
The only thing I can think of is to wonder if the way that VMS handled TE16
(i.e. massbus) tape drives changed between VMS 3 and VMS 4 and that somehow
there is a bug in simh that only rears its head on the earlier version. I
confess this is a stab in the dark.
Anyone got a bright idea about this?
Cheers
Peter Allan
On 6 November 2017 at 10:27, Peter Allan <petermallan at gmail.com> wrote:
> Thanks Johnny.
>
> The tape file contains several BACKUP savesets - it is actually the
> distribution tape for VMS 3.0 - so I presume that the CRC checks are part
> of the BACKUP saveset.
>
> I thought that I had read some BACKUP savesets (though not this tape)
> using a simulated TE16 drive before, but I cannot be absolutely sure, so I
> will do some tests.
>
> Cheers
>
> Peter Allan
>
> On 5 November 2017 at 22:48, Johnny Billquist <bqt at softjar.se> wrote:
>
>> Ah.
>>
>> That sound like a simh problem. The tape file itself have one of a few
>> different formats, none of them even keep any CRC (at least none of the
>> ones I can think of right now).
>> The backing file storage just have the tape records. And obviously, since
>> the same backing file storage is used on both emulated tape drives, there
>> is obviously nothing wrong with the file.
>>
>> Any CRC indication is purely made up in simh. And that is where you get
>> the error indication. So I guess someone needs to dig into the emulation of
>> the Massbus tape drives.
>>
>> And to directly answer your question - no I didn't know of any
>> difference, and was not aware of this problem. Maybe someone is, but I
>> haven't seen/heard anything, and noone have said anything here so far
>> either.
>>
>> Johnny
>>
>> On 2017-11-05 20:19, Peter Allan wrote:
>>
>>> Quite right Johnny. I obviously was not clear about the problem.
>>>
>>> Essentially, when trying to read a tape file using a simulated TE16 tape
>>> drive (on a simulated VAX 780 running VMS 3.0), I get CRC errors, yet when
>>> I try to read the same tape file with a simulated TS11 tape drive, it works
>>> perfectly. My question is - is there any explanation for this different
>>> behaviour?
>>>
>>> Peter Allan
>>>
>>> On 5 November 2017 at 17:00, <simh-request at trailing-edge.com <mailto:
>>> simh-request at trailing-edge.com>> wrote:
>>>
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>>> Today's Topics:
>>>
>>> 1. Re: VMS 1.5 installable? (Johnny Billquist)
>>>
>>>
>>> ------------------------------------------------------------
>>> ----------
>>>
>>> Message: 1
>>> Date: Sun, 5 Nov 2017 12:55:16 +0100
>>> From: Johnny Billquist <bqt at softjar.se <mailto:bqt at softjar.se>>
>>> To: simh at trailing-edge.com <mailto:simh at trailing-edge.com>
>>> Subject: Re: [Simh] VMS 1.5 installable?
>>> Message-ID: <6a250afb-9965-c07a-284b-3d25d8bfb76f at softjar.se
>>> <mailto:6a250afb-9965-c07a-284b-3d25d8bfb76f at softjar.se>>
>>>
>>> Content-Type: text/plain; charset=utf-8; format=flowed
>>>
>>> Well, obviously there are differences. The TE16 is a Massbus tape
>>> drive.
>>> The TS11 is a Unibus thing. Totally different. Both in how they
>>> connect,
>>> how the programming model is, the exact layout of registers, and of
>>> course then, through which bus interface you program them.
>>>
>>> In essence, they have nothing in common, apart from that they both
>>> use
>>> the same physical tape medium in real life.
>>>
>>> Johnny
>>>
>>> On 2017-11-05 11:39, Peter Allan wrote:
>>> > Thanks to Wilm, I now have VMS 1.5 up and running. This is new
>>> territory
>>> > for me since my first exposure to VAXen was in late 1982 when the
>>> > version was something like 3.0, or just possibly the last version
>>> of
>>> > 2.x. (I didn't pay attention to such things back then. If I could
>>> write
>>> > Fortran programs, I was happy.)
>>> >
>>> > However, the fact that I could complete the installation of VMS
>>> 3.0 by
>>> > using a simulated TS11 tape drive when it failed with a TE16
>>> drive has
>>> > got me wondering if there is a bug in simh. Surely on a real
>>> system you
>>> > could use a real TS11 or TE16 drive? Obviously there is no
>>> density on a
>>> > simulated tape file, but is there any other difference between
>>> the two
>>> > simulated tape drives that explains what is going on?
>>> >
>>> > Cheers
>>> >
>>> > Peter Allan
>>> >
>>> >
>>> > On 25 October 2017 at 14:08, Peter Allan <petermallan at gmail.com
>>> <mailto:petermallan at gmail.com>
>>> > <mailto:petermallan at gmail.com <mailto:petermallan at gmail.com>>>
>>> wrote:
>>> >
>>> > Thanks Wilm, I will try that out. I doubt I would have
>>> thought of
>>> > using a TS11 rather than a TE16 without your advice.
>>> >
>>> > Peter
>>> >
>>> > On 25 October 2017 at 12:39, Wilm Boerhout
>>> <wboerhout at gmail.com <mailto:wboerhout at gmail.com>
>>> > <mailto:wboerhout at gmail.com <mailto:wboerhout at gmail.com>>>
>>> wrote:
>>> >
>>> > Your approach is correct, I have regularly used it over
>>> the past
>>> > weeks to bring up VMS 1.0.
>>> >
>>> > I also saw these CRC errors on restore sometimes. There
>>> are two
>>> > ways around this:
>>> >
>>> > 1. Mount the 3.0 tape on a generic (newer) VAX/VMS
>>> system, use
>>> > $MOUNT/OVER=ID and copy the LIBRARY and OPTIONAL
>>> savesets to a
>>> > (RP06-sized) disk in the [0,0] directory. In a later
>>> step, $
>>> > mount
>>> > /foreign this disk, and point the installer to this
>>> disk as
>>> > the source.
>>> > 2. On your 3.0 system just booted with just the REQUIRED
>>> > saveset, use a
>>> > TS11 and not a TE16 tape unit in the simh config.
>>> Somehow this
>>> > worked. Also, when you use a TE16, use an explicit
>>> $MOU/FOR
>>> > /DEN=800. I forget in which version, but this also
>>> worked
>>> > sometimes.
>>> >
>>> > HTH
>>> >
>>> > /Wilm
>>> >
>>> >
>>> > Peter Allan schreef op 25-10-2017 om 13:30:
>>> >
>>> > Encouraged by all of the posting about running VMS
>>> 1.5 on an
>>> > emulated VAX 780 with simh, I have tried to do the
>>> same.
>>> > However, I am having a problem.
>>> >
>>> > I don't have an existing VMS 3.x system running (4.6
>>> is my
>>> > earliest), so I tried to do a VMS 3.0 installation
>>> using the
>>> > tape from uni-stuttgart which I had downloaded some
>>> time ago.
>>> >
>>> > I booted a VMS 4.6 system on an emulated 780 and did
>>> an
>>> > image restore using BACKUP of the REQUIRED saveset on
>>> the
>>> > VMS 3.0 installation tape to an RP06. So far, so
>>> good. Then
>>> > I booted the newly created RP06 disk, which continued
>>> the
>>> > installation process by attempting to restore the
>>> LIBRARY
>>> > saveset on the VMS 3.0 tape. However, this crashed
>>> with too
>>> > many CRC errors.
>>> >
>>> > This is where I am stuck. I could download the tape
>>> from
>>> > uni-stuttgart again, but is there any reason to
>>> expect a
>>> > better result by doing this? Can someone who has got
>>> this to
>>> > work advise me what to try next please. I have
>>> downloaded
>>> > the files that Christian posted, but while that has
>>> > standalone backup on a disk image, I need DSC to read
>>> the
>>> > VMS 1.5 tape (don't I?) which is the only reason that
>>> I was
>>> > trying to get VMS 3.0 working in the first place.
>>> >
>>> > Cheers
>>> >
>>> > Peter Allan
>>> >
>>> > On 20 October 2017 at 09:43, Wilm Boerhout
>>> > <wboerhout at gmail.com <mailto:wboerhout at gmail.com>
>>> <mailto:wboerhout at gmail.com <mailto:wboerhout at gmail.com>>
>>> > <mailto:wboerhout at gmail.com
>>> <mailto:wboerhout at gmail.com> <mailto:wboerhout at gmail.com
>>> <mailto:wboerhout at gmail.com>>>>
>>> > wrote:
>>> >
>>> > Matt Burke schreef op 17-10-2017 om 23:17:
>>> >
>>> > You may also want to try VAX/VMS 1.0 (or as
>>> close
>>> > as you can
>>> > get to it):
>>> >
>>> >
>>> > http://www.9track.net/vms/BB-D782A-BE.zip
>>> <http://www.9track.net/vms/BB-D782A-BE.zip>
>>> > <http://www.9track.net/vms/BB-D782A-BE.zip
>>> <http://www.9track.net/vms/BB-D782A-BE.zip>>
>>> > <http://www.9track.net/vms/BB-D782A-BE.zip
>>> <http://www.9track.net/vms/BB-D782A-BE.zip>
>>> > <http://www.9track.net/vms/BB-D782A-BE.zip
>>> <http://www.9track.net/vms/BB-D782A-BE.zip>>>
>>> >
>>> > This is not taken from an original tape. It's
>>> > something I
>>> > reconstructed
>>> > from a disk containing early VAX/VMS source
>>> and
>>> > binaries. The
>>> > dates
>>> > indicate that this is earlier than VAX/VMS
>>> 1.5.
>>> > Hopefully someone can find an original at
>>> some point.
>>> >
>>> > Matt
>>> > ______________________________
>>> _________________
>>> > Simh mailing list
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>>> <mailto:Simh at trailing-edge.com <mailto:Simh at trailing-edge.com>>
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>>> <mailto:Simh at trailing-edge.com>>>
>>> > http://mailman.trailing-edge.com/mailman/listinfo/simh
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>>> > <http://mailman.trailing-edge
>>> .com/mailman/listinfo/simh
>>> <http://mailman.trailing-edge.com/mailman/listinfo/simh>>
>>> >
>>> > <http://mailman.trailing-edge
>>> .com/mailman/listinfo/simh
>>> <http://mailman.trailing-edge.com/mailman/listinfo/simh>
>>> > <http://mailman.trailing-edge
>>> .com/mailman/listinfo/simh
>>> <http://mailman.trailing-edge.com/mailman/listinfo/simh>>>
>>> >
>>> >
>>> > Wonderful!
>>> >
>>> >
>>> > I now have VMS 1.0 up and running on simh
>>> VAX780. Does
>>> > anyone know
>>> > whereto find the Fortran installation tape for
>>> this system?
>>> >
>>> >
>>> > BTW, I also use a fine VT52 emulator I found on
>>> github.
>>> >
>>> >
>>> > /Wilm
>>> >
>>> >
>>> > _______________________________________________
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>>> >
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>>>
>>> --
>>> Johnny Billquist || "I'm on a bus
>>> || on a psychedelic trip
>>> email: bqt at softjar.se <mailto:bqt at softjar.se> ||
>>> Reading murder books
>>> pdp is alive! || tryin' to stay hip" - B. Idol
>>>
>>>
>>> ------------------------------
>>>
>>> Subject: Digest Footer
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>>> ------------------------------
>>>
>>> End of Simh Digest, Vol 166, Issue 12
>>> *************************************
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>>
>> --
>> Johnny Billquist || "I'm on a bus
>> || on a psychedelic trip
>> email: bqt at softjar.se || Reading murder books
>> pdp is alive! || tryin' to stay hip" - B. Idol
>> _______________________________________________
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