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101090 discussions

Need picture of power supply mounted in 11/40 cabinet

by pbirkel＠gmail.com

Marc: Do you have the 11/40-specific wiring harness? Assuming that you do it's a bit tricky -- not so much mounting a given supply (aside from the fact that they are heavy and awkward to work with even when minimally populated), but because there is a very tight tolerance between them to thread the wiring harness. I've determined the hard way that you really need to install the lower one first, then the harness, then the upper one. At least for me it wasn't practical/possible to install the harness after-the-fact. There's also a bit of work involved in threading both of the AC power cables plus the pair of power-control cables (assuming that you're using a DEC power controller) via the right-side vertical rack channel -- which also interact with the power harness placement. Once everything is cabled-in-place the result is maximally compact, but getting there is not simple. Yes, the power cable wiring isn't well-described anywhere IMO. You have to stare at the puzzle-pieces for a while and "dry fit". Harness shape/stiffness helps eyeball how to fit the pieces together, but the importance of the rack vertical side-channel in making everything fit is not, IMO, made at all clear anywhere in the various documentation -- although it can be inferred from careful examination of a few graphics in various documents. The 11/40, the 11/45-50-55, and the 11/70 share the same design in this respect so documentation for one will serve you well in any of these cases. If you can tackle the task *before* installing the BA11 chassis you'll find it easier. If you're not using a standard DEC rack or don't have an equivalent vertical side-channel to work with then IMO you'll need to get very creative ... and the 11/40-specifics wiring harness may not work at all and you'll need to build your own. Fortunately I didn't need to explore that path ... Good luck! -----Original Message----- From: cctech <cctech-bounces at classiccmp.org> On Behalf Of Marc Howard via cctech Sent: Saturday, December 4, 2021 10:28 PM To: General Discussion: On-Topic Posts Only <cctech at classiccmp.org> Subject: Need picture of power supply mounted in 11/40 cabinet Hi, I've got an 11/40 I'm going to start working on. Problem is that there are two power supplies (H742 and H7420) that came with it but neither was mounted in the rack. Could someone post/send/etc. photos of how the power supply mounts in the rack? Also how is the power cabling routed (I think I'm missing this part)? Thanks, Marc Howard

4 years, 1 month

Need picture of power supply mounted in 11/40 cabinet

by w9gb＠icloud.com

Power Supplies, due to their Weight, are placed at the bottom of Racks (prevent tip overs / weight distribution). https://avitech.com.au/?page_id=366 The PDP-11/70 Maintenance and Installation Manual (EK-11070-MM-002) explains that the basic PDP-11/70 system components are located in a double cabinet as shown in Figure 1-1 of that manual. https://i0.wp.com/avitech.com.au/wp-content/uploads/2016/05/major-assemblie… greg > Date: Sat, 4 Dec 2021 19:28:01 -0800 > From: Marc Howard <cramcram at gmail.com> > To: "General Discussion: On-Topic Posts Only" <cctech at classiccmp.org> > Subject: Need picture of power supply mounted in 11/40 cabinet

4 years, 1 month

RK11-C indicator panel inlays?

by jnc＠mercury.lcs.mit.edu

Let me get this out before the list gets shut down _again_... There is discussion of doing a run of indicator panel inlays: http://ana-3.lcs.mit.edu/~jnc/tech/DECIndicatorPanels.html for the RK11-C (which is wired for an indicator panel, although as far as I know, DEC never did the inlay). If you're interested... you will need a standard DEC indicator panel light panel (with flat cables with plug-in-cards on the ends). (I don't have any insight on how to get one of those. It shouldn't be _too_ hard to make replicas, but I'll leave that topic for the moment.) All I am proposing to do is create the silk-screened inlay that turns a DEC indicator panel into an RK11-C indicator panel (starting with a functional indicator penel without the inlay). All DEC indicator panels use the same actual light panel and flat cables/plug-in-cards (which have one conductor per light in the light panel); which light comes on is set by the way the backplane slots the cables/plug-in-cards plug into are wired. So from the prints, which give the wiring to the indicator panel slots, I managed to work out what an RK11-C panel would look like, roughly (captions are made up, but the light locations are accurate): http://ana-3.lcs.mit.edu/~jnc/tech/pdp11/RK11-C_inlay.txt Starting with that, Dave Bridgham managed to whip up a rough approcimation of what the inlay would look like: http://pdp10.froghouse.org/qsic/inlay-rk11-c.pdf We had put a certain amount of work into identifying a font which looks like the one DEC used, back when; I worked with a member the UK to produce a bunch of blank inlays (right size/shape, with the black paint on the back with the holes for the lights). Dave then found someone who could print the white lettering on the front, and this is what the result looked like, on an 'RK11-F' (the QSIC with RK emulation microcode) panel: http://ana-3.lcs.mit.edu/~jnc/tech/QSIC/jpg/RK11F-F.jpg You can compare with an original DEC inlay (TC08, IIRC) here: http://ana-3.lcs.mit.edu/~jnc/tech/QSIC/jpg/DasBlinken2F.jpg That's on the same light panel, just the inlay is changed. (The lights in the lower one are from the light panel Dave produced for use with the QSIC; it's totally incompatible, electrically, with the DEC originals; 4 wires, IIRC, run the whole thing (data, clock, latch and a ground), as opposed to the 'wire per light' of the DEC originals. Looks _just_ like the originals (which Tech Sq used to have a lot of, BITD), though. Anyway, if anyone is interested, the next step would be to find out who all wants an RK11-C inlay, and work out _exactly_ what would be printed on it. Noel

4 years, 1 month

Source for DEC TC01 (and similar) bulbs?

by michael.99.thompson＠gmail.com

> > > From: Josh Dersch <derschjo at gmail.com> > Subject: Source for DEC TC01 (and similar) bulbs? > > The Search Scope loop diagnostic shows block numbers going by in both > directions so a lot of the drive and controller are working, but there's > some glitchiness in bits 2, 5, 8, and 11 of the data so I need to trace > that down; I hope it's not the tape head. > > - Josh > So what do bits 2, 5, 8, & 11 have in common? All bits come from the same track on the tape head, and share some of the path to the Data Buffer. If you wrote this tape on this system, I would try reading a tape that was written on another machine to make sure that the problem didn't originate with writing. Check for a bad connection where the tape head cable connects to the G851 module in the TU55, where the G851 plugs into the TU55 backplane, and where the data cable plugs into the TU55 backplane, and possibly the K2 relay on the G851. In the TC01 you could swap the G888 module in slot C22, the S205 module in slot D05, the S205 module in slot E06, the S603 module in slot C02, or the R123 module in slot E08, with another one to see if the glitch moves to another bit. -- Michael Thompson

4 years, 1 month

FTGH: PDP-11 Software Source Book, 3rd Ed

by toby＠telegraphics.com.au

Hi, 2 volumes, Applications and System. See: https://imgur.com/a/ISXGK5N FTGH for postage from Toronto, Canada --Toby

4 years, 1 month

Hand tool to remove a difficult (stuck) circuit board

by wh.sudbrink＠verizon.net

I remember seeing this somewhere. I have done a fair amount of googling with no luck. I'm looking for a hand tool with a plyer like grip at the top of a shaft. At the bottom of the shaft there is a "foot" that, when you squeeze the grip, scissors open. The idea being that you slide the foot down between a daughter card and the motherboard it is stuck in and when you squeeze the grip, it lifts the card out of the slot. Anybody know what this tool is called and/or where to get one? Thanks, Bill S. -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

4 years, 1 month

External SCSI Drives on DEC2000 AXP

by cruff＠ruffspot.net

Have you verified that the SCSI bus is terminated properly? A missing or improperly configured terminator can sometimes cause those sort of symptoms.

4 years, 1 month

Reproduction DEC 144-lamp indicator panels (was Re: RK11-C indicator panel inlays?)

by ethan.dicks＠gmail.com

On Mon, Dec 6, 2021 at 9:42 AM David Bridgham via cctalk <cctalk at classiccmp.org> wrote: > The inlays are mostly not done with any tools I have. I do the graphics > with Inkscape. Rod made up the blanks with silk screening. Then I have > the white printing done at a printshop I found who has a large, flatbed > printer that can print white ink. I do have some ideas about how I > might try to make up blanks with a laser etcher I have access to but at > the moment we have an ample supply. Cool. > Also, I've experimented with making my own bezels out of PVC board from > Home Depot using a CNC router. In the pictures below, the yellowed > bezels are old DEC bezels while the white ones are ones I made. I > figured that if we ever get the QSIC shipping and people want indicator > panels (I hope they'll want indicator panels), I'd rather not depend on > them ripping apart old DEC bezels to make this work. Yes. I'd rather not demolish my only indicator panel. I was planning on demolishing a blank (I have a few short blanks, but most people do not) > Anyway, I'd be most happy to have another person with more tools to help > build bits and pieces of this stuff. I've noticed that as I gained > access to different tools, I came up with different ideas about how to > make things. I didn't think the laser etcher was all that useful until > I started using it. I have a small 40W laser etcher that I essentially haven't used since I have had access to large-format 80-120W laser cutters. As for tools, I can rent a 4'x8' Shopbot router at our local Makerspace that can turn out the light blocking bar or, from your file, the frame. We also have a local company (IC3D) that makes cubic-meter 3D Printers and makes their own filament from pellets, keeping costs down. The founders are friends of mine and I've helped repair sensors on their manufacturing line. If I had an STL, I could get a bid on what it would take to 3D print one. It wouldn't be as smooth as a machined PVC foam milled one, but it would be strong. With a little post processing, a 3D Printed frame may give an adequate look. Just a possibility. I haven't worked with PVC foam much but I understand the principle. > Now I want to use it for everything. Turns out it > can't quite handle 3/8" Delrin; it just melts it and makes a mess. That sounds like a power problem. Normally, Delrin lasers quite nicely, at least at 80W. Thick stuff is hard in any printer because of lenses, beam diffusion, etc. We sometimes have problems with 1/2" material of any kind in ours. I've done some stuff in 2 passes, one high, one low (refocusing/repositioning Z axis between job runs). We also have multiple lenses for different focal points. One is only good for etching/surface work, and one is good for cutting 3/8" and thicker materials. We usually use the middle one since 99% of what goes into our laser is 3-6mm stock. > Speaking of help, if anyone wants to review the QSIC design, I'd welcome > that. This is by far the most complex circuit board I've ever designed. I could take a look at it, I have some background in making Qbus and Unibus interfaces, but how useful I'd be depends on what kind of feedback you are looking for. > Back to indicator panels, here's a picture showing a bit of the > evolution of my indicator panels... > > http://pdp10.froghouse.org/qsic/indicator-panel-stack.jpg > > ... The only real thing I'd like to > change is the gloss. Somehow, DEC's inlay is as flat as flat can be. I did notice that. I have no idea what to recommend. AFAIK, DEC just used an acrylic with a specific surface texture. The only stuff I can get is like what you have - smooth as window glass. Cheers, -ethan

4 years, 1 month

Women of computing

by compoobah＠gmail.com

On Sun, 2021-12-05 at 12:00 -0600, Brie wrote: > > He may as well have just come out and said, ?It triggers me and I > don?t like having to acknowledge that women exist in the field of > computer history.? > > ? Brie Sorry to go off topic, but I have friends and family who are veterans or otherwise have had horrible experiences. They get triggered. What this sentence is describing is someone getting mildly annoyed.

4 years, 1 month

Unrecognized DEC Power Supply in PDP-11/44 Configuration

by pbirkel＠gmail.com

Does anyone recognize the (presumably) DEC power supply on the front half of the rack-bottom in the 11/44 listing at: https://www.ebay.com/itm/363640137050 Blurry photo, but it looks like there are a 4x3, a 3x3, and a 3x5 Molex connector, and two brown mini-modules protruding from the right side. If so, then what purpose did it likely serve? It appears that the 6U immediately below the 11/44 was likely occupied by an RX02 given the presence of an M8256 in the 11/44 backplane (and skinny mounting rails, although I thought those were usually at the bottom of the RX02), and that included its own power supply (which wasn't very beefy either, nor did it need to be). What went into the 6U immediately above the power supply is unclear; there is a HEX Wespercorp TC130 Tape Controller as well as three unknown QUAD modules in the 11/44 backplane. Perhaps there was a horizontal autoload tape drive mounted there that required a separate power supply? Curious! paul

4 years, 1 month

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