Peter, My reading of your hardware setup sounds like what was called a "Mixed-MASSBUS" configuration, that is, mixing disks and tapes on the same MASSBUS. PDP-11 RSX-11M-Plus supported Mixed-MASSBUS. We dual-ported all our disks and used the MASSBUS that came with our tape drives that way. I think Mixed-MASSBUS support was unusual. I do not remember if VMS 3.0 supported Mixed-MASSBUS. If not, what you are seeing might be the result.
Larry Baker US Geological Survey 650-329-5608 ba...@usgs.gov > On 7 Nov 2017, at 12:54:40 PM, simh-requ...@trailing-edge.com wrote: > > ------------------------------ > > Message: 4 > Date: Tue, 7 Nov 2017 20:54:31 +0000 > From: Peter Allan <petermal...@gmail.com <mailto:petermal...@gmail.com>> > To: "simh@trailing-edge.com <mailto:simh@trailing-edge.com>" > <simh@trailing-edge.com <mailto:simh@trailing-edge.com>> > Subject: Re: [Simh] Simh Digest, Vol 166, Issue 12 > Message-ID: > <cajcrz55fv2ube5phmtbouxl5yzt8cpyiyhn1cygxghzhbxe...@mail.gmail.com > <mailto:cajcrz55fv2ube5phmtbouxl5yzt8cpyiyhn1cygxghzhbxe...@mail.gmail.com>> > Content-Type: text/plain; charset="utf-8" > > 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 > > >
_______________________________________________ Simh mailing list Simh@trailing-edge.com http://mailman.trailing-edge.com/mailman/listinfo/simh
