test-drb September 2015

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MARC

by aek＠bitsavers.org

http://www.loc.gov/marc/

8 years, 7 months

Cloud-cuckoo land

by jnc＠mercury.lcs.mit.edu

I'm not sure which is more amusing: http://www.ebay.com/itm/191523958984 the price they expect to get, or calling it a 'mainframe'. Noel

8 years, 7 months

Regarding Manuals

by jnc＠mercury.lcs.mit.edu

> From: Jerome H. Fine > I have ... some PDP-11 hardware manuals, but probably most are already > in PDF files at bitsavers. Any chance you could check to see if you have something that's not online? If you have more than a few, you probably do have some that aren't online. If you whip up a list of what you've got, I'd be happy to check it for you. Noel

8 years, 7 months

Half an extra finger (DEC PDP-8/A G8018 regulator)

by charlesmorris800＠centurytel.net

As I've periodically posted, my 8/A has an intermittent power supply problem (Power OK light and signal line flickers, so the entire system is confused. Throwing the DC breaker and resetting it will often make the problem go away for the rest of the evening). It's slowly getting worse, to the point where tonight the Power light wouldn't come on at all. It's not the breaker itself. So I decided to put the G8018 regulator assembly on the extender card. However, when using the extender, the DC breaker would immediately trip! I tracked it down to the +5 volt crowbar being triggered. Careful examination of about four different schematic pages shows a connection on the backplane between edge connector pins BP2 & BR2 and the multiple +5 volt busses on edge conn C. If you look at the schematic, BR2 is a test point but BP2 goes to the anode end of the 5.7 volt zener that sets the crowbar voltage (its cathode is connected to +5) and through a 10 ohm resistor to the crowbar SCR gate with 100 ohms to ground. This makes *no* sense because that connection shorts out the zener, so as soon as the +5 comes up, 100/110 of the +5 is applied to the SCR gate, so naturally it fires! A close look at the G8018 provided the answer. There is half a finger etched on BP2 which is also fully connected to BR2. (See picture) Looks like a drafting mistake to me. The Douglas extender board has sufficient depth in its female connectors that the partial finger of BP2 made contact and caused the crowbar to trigger as described. Cutting the "web" between the fingers fixed the problem. Naturally the intermittent flicker is gone for now, and I doubt it was an "almost" connection to the SCR gate because once it fires, the +5 should drop to near zero and trip the breaker, which has not been the case (except with the extender card). But at least I have the regulator on the extender card so I can start measuring when it comes back! http://s1181.photobucket.com/user/DrCharlesMorris/media/PDP-8/P09-26-15_20.…

8 years, 7 months

cctalk Digest, Vol 15, Issue 26

by mark＠markesystems.com

>>> As I mentioned in another response, I truly dislike SQLite, based on my >>> experience with it on my Garmin GPS. >> >> I'm still not sure why - my experience has been very good. What bad >> experiences have you had? >> ~~ >> Mark Moulding >> > > My Garmin has had data integrity issues in its database. Plus, lack of > *convenient* tools, and having to rummage around here and there to find > them. > > On top of that, this will be part of an online web app some day, so > having the database in the address space of the web server is probably > not a Good Thing. I haven't used SQLite in an embedded environment yet. I wonder if it tends to thrash certain areas of the data file (which would cause flash wear problems). I appreciate the data point... And yes, SQLite was not intended for a high-volume multi-access environment, and my experience is definitely from embedded up through low multi-user local network applications. I'm sure there are many good reasons why MySQL has become the standard for web server applications. I originally understood - perhaps erroneously - that this was to be a smallish, local application, and for me (and the smallish types of systems I tend to build), I'd prefer to avoid the headache of administering the MySQL subsystem. But I stand by my statements about the separate, non-editable keys... :-) ~~ Mark Moulding

8 years, 7 months

Video tour of 1985 home automation system

by sellam＠vintagetech.com

I wanted to share this because it's pretty neat: https://www.youtube.com/watch?v=0BHIknNa6Eg It's a ~6 minute tour of a home automation system from the 1980s that features graphical floor layouts and touch screen programming. The system is built into the house. -- Sellam ibn Abraham VintageTech ------------------------------------------------------------------------------ International Man of Intrigue and Danger http://www.vintagetech.com Whatsoever a man soweth, that shall he also reap. The truth is always simple. * * * NOTICE * * * Due to the insecure nature of the medium over which this message has been transmitted, no statement made in this writing may be considered reliable for any purpose either express or implied. The contents of this message are appropriate for entertainment and/or informational purposes only. The right of the people to be secure in their papers against unreasonable searches and seizures shall not be violated.

8 years, 7 months

DEC BA11K Fan repair

by lyokoboy0＠gmail.com

I have a BA11K power supply out of a pdp 11/34 that has frozen up fans. They are frozen up pretty bad. I heard from another list member here they are repairable, any advice on how to do so? --Devin

8 years, 7 months

Backups [was Re: Is tape dead?]

by jnc＠mercury.lcs.mit.edu

> From: Sean Caron > the worst thing on the market since the old Quantum Bigfoot Just out of curiousity, what was so bad about the Bigfoot? Noel

8 years, 7 months

Looking for some DEC-related spares..

by jnc＠mercury.lcs.mit.edu

> From: tony duell > They would never take being straightened, the metal is partially > fractured already. Ah. OK. Well, a later poster mentioned a possible source of new feet - I had assumed you wanted exactly identical ones, which may not be available, but if all you want is functionality, you can probably find that from the sources they provided. > I have found a little 4 slot Qbus box with 3 swtiches on the front, > these seem to be the same mechanisms behind the toggles. Yes, they are: I fixed an 11/05 front panel with switches sourced from one of those 11/03 front panels. I hated to do it, but the 11/03 panel was a spare, and as you say, if the switches ever re-appear, I can repair it. Noel

8 years, 7 months

Looking for some DEC-related spares..

by jnc＠mercury.lcs.mit.edu

> From: tony duell > 2 of said feet got bent at right-angles (!) Hammer them straight, and clean up the threads with a die. Those outriggers are unobtainium, so I can't imagine the feet are much better. > switch mechanisms for the PDP11/45 front panel. I have the toggles > (thankfully), I need the switches Now you're really into unobtainium territory. We've been moaning about the inability to find these for a while now. All the early 11's (except the 11/20) use these - 11/05, 11/40, 11/45, etc - and a bunch of us need them, but nothing doing. Noel

8 years, 7 months

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test-drb September 2015