Thanks to everyone for their suggestions. To answer Bob's questions:
1) I am using the vmb.exe image that comes with simh 2) The hang does not occur in SYSBOOT. I can get into SYSBOOT, look at the parameter values, change them and type CONTINUE. That is when the system hangs. Yesterday I tried a minimal boot by going into SYSBOOT and typing SET/STARTUP OPA0:, but that did not help. 4) I will try using the Massbus and RP debugging capability and see what it tells me. I am running this on a recently purchased quad-core system that is rather fast. I have simh set up on a system that is much slower, so I will give that a try to see if there is a difference. Cheers Peter Allan On 26 January 2011 12:44, Bob Supnik <bsup...@comcast.net> wrote: > I agree with Dave Hittner: the hang in booting VMS 4.6 from Massbus is > either a timing problem, or a bug in replicating some small detail of the > Massbus controller. > > Because booting from an RA81 waits in the same place (but eventually > succeeds), the "branch to self" loop where the simulator is waiting appears > to be an idle loop, where VMS is waiting for some sort of event, like a disk > interrupt. The disk interrupt may have occurred too soon and been lost (a > problem which occurred in DEC PDP-11 operating systems and in BSD Unix as > well). Or some detail that was unimportant in VMS 7.x mattered in VMS 4.x, > such as the handling of attention interrupts versus data transfer > interrupts. For an example of the kinds of details that could go wrong, see > http://simh.trailing-edge.com/docs/massbusmystery.pdf, which documents an > error in the 7.X driver sources for these disks. > > What would be most useful would be a VMS 4.X source set, but up until now, > no one in the community has found one. So here are some questions and ideas > for debugging this problem. > > 1. Are you using the VMB (primary boot) image that comes with the 4.X > series, or the default VMB image that comes with the simulator, which is > from 7.2? While I don't know of any version skew issues, they could > certainly exist. Does the same problem occur when booting with a 4.X VMB? > > 2. Does the hang occur in SYSBOOT (secondary boot), or in VMS proper? VMS > runs at high virtual memory (8XXXXXXX), yet the branch to self is in low > memory. If the hang is in SYSBOOT, the problem is likely to be easier to > solve, as the environment is simpler. One thing to check: is memory > management enabled? > > 3. Other users have reported success in getting early versions of VMS to > run. I seem to recall that versions as far back as 1.5 have run > successfully. Can we get a census of which versions have been successfully > tested on the 780 booting from Massbus, and what version of VMB they use? > > 4. Both the Massbus controller (RH) and the device (RP) have debugging > capabilities. You can log every register read and write to see how far the > the controller gets. > > 5. As a last resort, zip up your RP disk image and post it to an uploading > site, like Megaupload, so that others in the community can try their hand at > the problem. You'll need to include not just the disk image, but > configuration data, as well as any auxiliary files (such as an earlier VMB, > if you use one). > > /Bob Supnik > > > _______________________________________________ > Simh mailing list > Simh@trailing-edge.com > http://mailman.trailing-edge.com/mailman/listinfo/simh >
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