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VAX 11/780 Site Planning

NF6X

NF6X

Veteran Member
Joined
Sep 9, 2013
Messages
1,561
Location
Riverside, CA, USA
Recently, I've gotten this idea crazy stuck in my head that I would actually like to assemble a working VAX 11/780 system as the centerpiece of my vintage computer collection. Maybe I'd even frame up a computer room out in my barn/workshop, complete with raised computer room flooring? Realistically, the chances of actually pulling this off is somewhat less that 100%, and it would be a multi-year project for sure, but it'll be fun to play what-if anyway.

My imaginary system would be something like the system I recall working with a bit back at UC Irvine back around 1989-1992. I've never booted up or shut down a VAX, or even changed a disk pack, but I did tape backups on that system. As I recall, it had one expansion cabinet to the right of the main cabinet, a TU77 tape drive on the left of the main cabinet, and then two or more shorter cabinets to the left of the TU77 with hard drives. I recall them looking like RL02 drives, but I don't know if that makes sense. I never saw them rolled out of their racks, but the front panel of an RL02 looks like what I remember (quite possibly incorrectly) seeing back then.

I've found some caches of VAX 11/780 documents online, including some installation manuals. What I have not found yet is the sort of information necessary for site planning of an 11/780 installation: What are the dimensions of the main cabinet, expansion cabinet, TU77 tape drive, suitable hard drives, printing console terminal, maybe a line printer, etc? What are their power requirements? Floor loading? Cooling requirements? Clearance requirements for front and rear access?

Were there such site planning documents available back in the day that I might look for as either scans or original copies?

My barn/workshop that I could possibly host a 780 in is a 30'x48' steel building with a concrete floor. Among other things, it's a workshop for working on my old military trucks, doing metalworking, etc. I could possibly frame a computer room into a back corner rather than having machines out in the open. I have a 240V single phase 200A panel in the workshop. I understand that a 780 normally uses 3-phase power, but that it's possible to rewire one for single phase power. I have machine tools that use 3-phase with which I use a rotary phase converter, but I don't think that would produce clean enough power for a computer even if it was big enough. So, once I figure out how much 3-phase power a 780 installation would use, then I can look into how much it would take to set up a solid-state 3-phase converter big enough, since that could run my machine tools, too. I suspect it'd probably be way too expensive to do that.

I think this project idea is quite likely to be too ambitious, but given the space and power I do have available, it might just be borderline do-able for me. So, what do y'all think about my crazy project idea?
 
The 11/780 doesn't need much.

TECV01P10_16.jpg


It will work on a concrete floor with no space behind and almost none in front or at the sides.
 
I was thinking about having clearance to access the rear sides of the cabinet, but I guess I will only need that during system assembly and debugging. Once I get the system working, I can push it against a wall.

By the way, what is that "excellent space heater" in your signature? I've been meaning to ask about that. I don't recognize it.
 
SGI Onyx.
It may be -25 in the winter but it's +30 in the machine room. ;)

The way my racks are setup their backs are removed and there's a 6" cavity. A fan pulls air from the cavity behind through a duct in the wall to a plastered over fireplace in the other room. Once you know where air is drawn in and out of your system you can build the ventilation around that.
 
Wow, that Onyx must put out a lot of BTUs. I think that the only SGI systems I've been exposed to were Indigos.

A NeXT cube system is one of the things on my someday-wish-list, too. I thought those were really cool when they came out, and I got to play with one a bit back in college.

The wait for a nice PDP-xx or VAX-11/7xx system to appear sure seems eternal to an impatient person like me! :)

I hope I'll have time to start digging into my recently acquired PDP-11/44 pile over the Thanksgiving break. Other projects and family time might prevent that, though.
 
Why not pour a little gasoline on this fire...

Suggested reading Dual Processor VAX 11/780 paper.

It also poses some questions you might want to think about before leaping.

Still, your quest will be governed by the hardware you find available to you. Begin immediately and pass up nothing. [especially cabinetry] These things get scrapped too often.

Look for: PDP-11/780 Hardware Installation Planning Guide - it's what you need.

I'm afraid I disagree about the raised floor... it's a must. [an absolute if you have any MASSBUS peripherals] If you want the machine to run, you need to plan for it to be maintained - front rear and underneath access. Otherwise, it won't stay that way long, especially if powered part time.

Pretty sure the power needs are like that of the 11/70 - 3-phase. Better check. It really needs CTCH.

Wasn't the final incarnation of the series a 785? Don't recall now.


So... UNIX?
 
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Begin immediately and pass up nothing. [especially cabinetry] These things get scrapped too often.
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I know this sounds like a way to very quickly amass piles of otherwise useless hardware (and with DEC stuff it takes up a LOT more space) but after a while it begins to make sense. I did this when 386's and 486's were on every curb. Was one of the best decisions I made when the gold bugs made everything from that era scarce a few years later.
 
Grabbing what I can find whenever I find it sounds like a good idea to me, too. I can always use stuff as trade fodder. I may end up with a different system than my ideal just because of availability, just like I'm starting off with a PDP-11/44 that wouldn't have been my first choice, but it's what turned up.

Yes, I believe there were 780 through 785 models. I think any of them would satisfy my desire for something 780-like. The 750 doesn't interest me as much, but it starts looking sexier once some RL02 or similar drives are in cabinets next to it. A friend used to have a 730 with an RL02 or two in its cabinet, and it was pretty neat. He also had a 725. Now I wish I could go back in time and get those from him, but I didn't know how much they interested me back then. They were just exciting from the "OMFG my friend has two VAXen!" weirdness factor. :)

For operating system. 4.3BSD would be my first choice. I might be interested in playing with VMS a bit to learn about it, but I never liked it back in the day.

I wonder how many MASSBUS boa cables managed to evade metal recyclers? I remember coils of abandoned MASSBUS cables down under computer room floors back then that nobody bothered to drag out after their VAXen were retired. Those are probably mostly long gone now.

I do have a stack of RL02 disk packs already in various states from apparently unused to definitely used. I would dearly love to get an RL02 drive to go with them, and I think that my PDP-11/44 pile includes one of the controller cards for them. A proper DEC cabinet for the PDP-11/44 + RL02 would be great to find, too. For now, I'm watching Craigslist and eBay, and telling everybody I see that I'm interested in DEC hardware.
 
Here's the best I've come up with: 11/780 installation guide, it should familiarize you with what to look forward to. (I think the Planning Guide was in the S&O Catalog)

Highlights you'll need for a low to mid-size system:

Power:

  • 120v/208v [240v] 3-phase Y 30Amps service
  • 10A for the CPU and SBI cabinets
  • single phase 120/240v for the UNIBUS cabinet (20A/10A)

System weight: - well north of 2000 lbs plus peripherals.

Area: - varies depending on what you find. If you plan for the minimum, you'd better also pre-plan how you'll expand it should that happen, otherwise there will be a lot of waste in the do-over.

I could see a "small size" system fitting in a 10'x10' area. But for planning's sake - it could be more than double. So for example 15'x20' might be a good "expanded" size to keep in mind for Phase 2.

You'll see what I mean from the manual.

Storage: - In general, the system shouldn't be exposed to more than 40% humidity and for the components to last, keep it well above freezing. If it's to be kept in conditions that are un-controlled - consider putting it under a heavy plastic tarp and keeping 300 watts of incandescent lights inside on the bottoms of the cabinets. This will help prevent condensing conditions and hopefully keep things above freezing. Of course, these conditions are ideal for rodents and insects, so include precautions against them as well.

Give thought to mold prevention and detection.

Operating: - 50 - 85 degrees ambient, 10-40% RH. There may be some dissenting opinions on this.

Specific Cautions:
  • Do not install the system in a building with solvents, petrol products, leather, evaporating liquids or chemicals. [i.e. - Chlorines, Formaldehydes, etc...]
  • All concrete surfaces of the area should be sealed, and preferably painted - particularly the floor. [A good conductive epoxy paint - maybe hangar floor paint?] Concrete dust is highly corrosive.
  • Ground the walking surface.
  • Ceilings should be reasonably dust free and sound absorbent
  • At least one wall should be sound absorbent - two adjacent ones is better.
  • Plan space for a printing console terminal and video terminal - with seating.
  • Space media / storage cabinets away from outside walls, especially if the structure is uninsulated.
  • Check to be sure you do not install UV producing illumination and prevent direct sunlight.
  • Include a CO2 fire extinguisher and smoke detector.
  • Emergency electrical service disconnect access in the computer room.
  • Do not smoke in the computer room.


Other:

If you were planning continuous or prolonged operation I'd suggest air conditioning and at least filtration. A good HEPA filter in the room will pay back in reducing drive and other system filter maintenance to zero.
 
I hadn't considered that concrete dust would be corrosive. Thanks!

Continuous operation is out just due to power cost, but filtration is a good idea anyway. This is a dusty area.
 
NF6X said:
...For operating system. 4.3BSD would be my first choice. I might be interested in playing with VMS a bit to learn about it, but I never liked it back in the day.

I wonder how many MASSBUS boa cables managed to evade metal recyclers? I remember coils of abandoned MASSBUS cables down under computer room floors back then that nobody bothered to drag out after their VAXen were retired. Those are probably mostly long gone now.

I do have a stack of RL02 disk packs already in various states from apparently unused to definitely used. I would dearly love to get an RL02 drive to go with them, and I think that my PDP-11/44 pile includes one of the controller cards for them...
Click to expand...

There's no shame in BSD UNIX. That link I provided [in the "gasoline" post] was to a paper from Dennis Ritchie's collection. It may even have been co-authored by him.

VMS [or OpenVMS?] would probably only interest an ex-DEC type or someone curious how a real-time prioritized preemptive multitasking heritage was implemented on VAX.

Keep collecting - it has a habit of "avalanching" on one, usually when you least expect it. An RL drive and cabinets will find their way to you. Every day, people like you and I are forced to give up on their dream system collections. Sad, but it's a fact. You KNOW they'd rather see it go to a good home than any other place. Just be there, and be ready.

Cables are the primary reason I feel a raised computer floor is a must for this "advanced" level of collecting. Air flow is another, but can be worked around. Unless you are lucky enough to have included a wide wire trough in your floor, there's really no practical alternative. Power and MASSBUS cables are hell to trip over. They're always in the way on the floor. Hard wired outlets are crazy for anyone planning to expand their system in any way, or keep it over time. Compared to other logistical considerations - this flooring is easy. You'll be so glad you did. You might even get lucky and get one free for the effort of de-installing it for the owner. [save some for me if there's extra ;)]
 
I'm going to disagree. For a system such as the VAX you don't explicitly need to have a raised floor OR fulfill even half those specific cautions. I've literally seen them running in a garage. They're RECOMMENDED, not REQUIRED. IF you want a raised floor, go the cheap way with 4x4's and plywood.
 
Well, I don't need a raised floor, but I sure do want one! And crappy fluorescent lighting, and a big red fake Halon system abort button next to the door that sets off a buzzer when it's pushed. :)
 
NeXT said:
I'm going to disagree. For a system such as the VAX you don't explicitly need to have a raised floor OR fulfill even half those specific cautions. I've literally seen them running in a garage. They're RECOMMENDED, not REQUIRED. IF you want a raised floor, go the cheap way with 4x4's and plywood.
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Yeah... different strokes for different folks. Everything I say is my opinion, some of it based on horrible bitter experience. Your mileage may vary.

I can't picture the plywood floor system though... how would you roll a 2000lb equipment rack across that?

NF6X said:
Well, I don't need a raised floor, but I sure do want one! And crappy fluorescent lighting, and a big red fake Halon system abort button next to the door that sets off a buzzer when it's pushed. :)
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LOL - I like the fake HALON system thing. Gonna get the klaxon horn with bubblegum light too? ...So great.

You know, for a regular PDP-11 that can be contained all in one cabinet, there's no problem no matter what you do. However, when one crosses over the MASSBUS barrier and starts talking 6ft long cabinets with 3-phase power - there comes a point... you realize you've got it real bad, and you may as well stop kidding yourself.

Women "design" and decorate a room at the drop of a hat... so why not go all the way and make a computer Batcave you can really get off on? I mean how many times in life are you going to get the chance?

If you got the itch... for heaven's sake scratch it if you can.

marmotking said:
“I spent half my money on vintage computers, software and documents. The other half I wasted.”
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