Patrick Finnegan wrote: You guys may very well be right on that, but still, I'll probably go through the motions anyway. It's just what I normally do. From what I can tell, looking at various stickers on and inside the unit, and comments from the donor, this system probably has not seen electricity in its veins for about 13 years. The last markings I see indicate 1994 as the last time it saw any recorded service. I don't know if that's long enough or not for these more 'modern' '80-ish caps to 'go bad' (what's the proper word for that exactly?) to the point of needing to be reformed. Anyway, I'll probably do it anyway, if for no other reason than to get a better understanding of how all the components in the chassis tie together. - Jared

Quoting Patrick Finnegan <pat at computer-refuge.org>: That's fair, but my method does not include the use of a variac. I pull the caps and slowly (10ma max current) bring them up to their rated DC voltage. I let them 'cook' for a while (overnight usually), until I see the leakage current drop and stabilize. Then I put them back in the PS, and check it out as a sub-system. Only then do I think about powering up the whole system. That's my method, anyway. - Jared

On Monday 08 October 2007 23:50, der Mouse wrote: Unless someone replaced it (unlikely, but it's possible), it does use the DEC-standard XX2247 ACE key. Pat -- Purdue University ITAP/RCAC --- http://www.rcac.purdue.edu/ The Computer Refuge --- http://computer-refuge.org

On 10/9/07, der Mouse <mouse at rodents.montreal.qc.ca> wrote: Mine do. As I've posted before, in over 25 years of working with DEC equipment, I've seen exactly *one* key that wasn't XX2247 (PDP-8/L-carcass-for-parts I got at Dayton in 1982). Your easiest choices are to either find a DEC enthusiast with a spare key, or to go to a full-service locksmith with that number, XX2247, and tell them you want a "code cut key". The last time I needed a code-cut key (for a video game cabinet), it was about $15. Newer machines that use the plastic key (11/24, 11/730...) can use an uncut tubular key - about $2 the last time I bought one of the _those_. Oh... since it's *much* cheaper to copy than code-cut, if you can borrow a key from someone, you could get it copied then returned. The problem with that, though, is that I've occasionally had problems getting round keys copied successfully. At one place (that I won't return to), I eventually dragged in the lock because three previous trips failed to produce a working key. -ethan

On 10/9/07, Gordon JC Pearce <gordonjcp at gjcp.net> wrote: Heh... that's one of the reasons for the intricate multiple-facet and other odd security keys - fewer locksmiths to license and train, and less of of chance of one of them getting "excitable". No... in my case, it wasn't that they *wouldn't* copy it - it was that the copies would barely turn in the lock because the depths weren't cut right and the pins were still binding. I finally came in with the lock so they could see how bad the copies were and so that I could leave with a good key. Fundamentally, I think the problem was that they didn't get lots of practice cutting round keys and so they just weren't good at it. -ethan

On 10/9/07, J Blaser <oldcpu2 at rogerwilco.org> wrote: Much harder. Boards store flat ;-) Very handy, but you should still check the backplane - all the list will show is a snapshot in time - not the final configuration. I've seen few machines where those labels were updated consistently. That makes sense. I know I went over bits of this before, but perhaps a different approach might be clearer... Systems Industries made a variety of disk/tape systems for various DEC machines. I have personally seen Qbus and 11/750 host cards, and I think there were others (Unibus, at least). To order an SI system, you'd tell the salesman what box you had, and what devices you wanted to attach. They would spec out the right host controller, and the right cards for the SI9900 external box to do what you wanted to do. I think there was also support for multiple hosts to access multiple disks - not like a true cluster, but more like multi-port access between a set of CPUs and a set of disks and/or tape. When I used an SI9900, it was nearly as simple as it could be. We had an SI 9700 board in our 11/750, a pair of 40-pin cables to SI 9900 box in the next rack, one host-side card in the SI 9900, and two SMD disk cards in the other half of the SI 9900 box. We had two SMD disks (60-pin control, 26-pin analog data) in the rack with the SI 9900, emulating a pair of RM03s and a large RM05. We could have chosen to hang more disks off our SI 9900, but the way SDI disks were plunging in price in the late 1980s, we kept the SI 9900 for our boot disk, and added a couple of RA81s for user data, etc. In your case, it sounds like the SI 9900 box you would run across (if it's still on-site to be found), would have one board with a pair of 40-pin connectors that would hang off of your CPU, then one or more tape interfaces, with, presumably, Pertec-style interfaces. One of the benefits of the 11/750 over, say, the 11/730, is that the CMI bus (I think that's what it was called) had really high bandwidth path to memory. You could hang a low-speed tape drive or two off of the Unibus, but for the free-standing 125 ips vacuum-column monsters, I just don't think the Unibus could keep the tape streaming. On our 11/750, we had that SI 9700 for system disk and one data disk, a UDA-50/RA81 for user directories, and an RH750 and TU78 for backups. It was hell to keep working, but when the TU78 was up, it *screamed* through backups. For your system, since it's going to be easier to find Unibus disk than an SI 9900, I'd recommend de-installing the SI 9700 (which involves twiddling the backplane jumpers on that slot to pass grant across the slot), and picking up a UDA-50. There were some Emulex Unibus SMD interfaces, but ISTR those were more common on PDP-11s and VAXen running UNIX, not VMS. Once the RA-81 fell below $20,000, SDI disks became really popular for sites without VAXclusters. That's one of the things _I_ would like to do with my 11/750 - mount an RA70 in the space to the left of the Unibus - where the battery-backup normally goes... stick a VT102 on top and have a single-cabinet 11/750 "workstation". :-) I do already have an 3-bay 8300 set up, so I'd also probably run a cable over to my RA81 port B, and my MDA 2.3GB ESDI-SDI box, but I'd like to be able to boot the 11/750 in-cabinet, without spinning up several amps of external disk. -ethan

[apologies for the long delay in responding. A spontaneous road trip without internet connectivity came up...] Ethan Dicks wrote: Okay, thanks for the further clarification, and sorry for being somewhat dense on this topic. I've had no success at finding _any_ SI 9700/9900 documentation, and since I have no prior VAX (or even DEC, except for playing with a few qbus -11s this past year) experience, I'm glad for the extra education. So, I guess that means that without the companion gear this 9700 of mine is pretty much useless to me, at present anyway. Sadly, I'm pretty sure that this box is long gone... Ah, more education. I don't know any of the specs of the CMI bus, but what you suggest makes a lot of sense, and would explain the presence of the SI 9700 board. Yes, this is just what I intend to do...unless, of course, the other chunk of the SI 9700/9900 shows itself underneath that enormous pile that the donor still has to sort through. All I need after getting the Unibus interfaces are a couple of gorillas to help me lift and mount those Super Eagles and the RA81 into some kind of rack (they're just stacked on the floor right now). :-) This would be a very cool configuration. Space and power are sometimes in short supply, so these kinds of 'non-standard' solutions serve the purpose of keeping these oldies alive. I might end up doing a similar thing. Depends on how dim the lights get when I turn on the 11/750 _and_ the Super Eagles and RA81! ;-) - Jared