test-drb January 2009

test-drb@ccmp.vtda.org

218 participants
340 discussions

Replacing failed powersupplies on qbus PDP-11s

by tiggerlasv＠aim.com

Since I'm not aware of your electronics/troubleshooting knowledge, I thought I'd make mention of one of the known BA23/BA123 issues. When the boxes were first introduced, they were shipped with backplane power cables that had a major design flaw. They used IDC-style connectors on each end of what was basically a heavy-gauge ribbon cable. The Insulation Displacement Connectors tended to add significant resistance to the connection, and couldn't carry their rated loads. Depending on the load, the connectors would either discolor from the heat. . . . start to melt, or, in extreme cases, start on fire. An FCO was issued, and the "proper" power cables have individual wires, and crimped-on pins. I don't think it would be unreasonable to speculate that, if your particular power supply had an old-style connector at some point (which chose to melt) that the solder joints for the header could have been compromised from the heat. Check the circuit board where the header is soldered, to make sure there aren't any cold or bridged solder joints. A shorted pin could prevent the power supply from coming up. . . If you have the old ribbon-style power connectors, I would recommend replacing them immediately. I "rolled my own" with parts readily available at MCM Electronics. I'm sure suitable connectors could also be obtained from Jameco, Digikey, etc. T

15 years, 3 months

Tektronix 4014-1 & unknown cards

by stephane.tsacas＠gmail.com

Hi, I just bought a Tektronix 4014-1, almost unused, for 10 euros ! The guy who sold it to me told me that it was connected to a "computer" which was located under a desk. He had removed the cards of this "computer", and had them stored, he gave them to me with the 4014. The inside of the 4014 and those unkown to me cards are displayed there : http://picasaweb.google.fr/sur.le.tas/Tektronix40141?feat=directlink (the "loupe" button on the top right might be useful). Also, in the 4014 docs, it seems I have one extra cards in the 4014, maybe the first one from the left ? Any idea what the other cards are ? Thanks -- Stephane Paris, France.

15 years, 3 months

Seeking reverse-engineers - Apple II VisiCalc

by trag＠io.com

>Date: Thu, 29 Jan 2009 09:07:20 -0600 >From: John Foust <jfoust at threedee.com> >Subject: Re: Seeking reverse-engineers - Apple II VisiCalc > At 01:00 PM 1/28/2009, Tim McNerney wrote: > > >> >I am looking for volunteers to help reverse-engineer and document >> Apple II VisiCalc. >> >I have three versions of the Apple II software. I know one of them >> still boots (1983?) >> >and have some confidence that the other two versions (1979 and >> 1981) work too. >> >I have been in contact with both Bob Frankston and Dan Bricklin. >> >Of course you ask, well then why do you need volunteers? >> >The answer is because no one can find the sources. >> > > No matter how many times I hear stories like this, or lived through > stories like this, I still shake my head and can't understand how the > source code gets lost. All these corporations, all the lawsuits, all > the programmers, all the marketing money, and so often no one, NO ONE, > preserves arguably the most important bits. What I find particularly irritating, is that the loss of the source code, arguably, defeats the implicit reason that copyright and patent protection exists in the first place. The U.S. constitution states: "To promote the progress of science and useful arts, by securing for limited times to authors and inventors the exclusive right to their respective writings and discoveries;" Now one could argue that securing the exclusive rights promotes progress all by itself. But the fact that it is meant to be for a limited time, implies to me that at some point the full benefit of that advancement should become available to everybody. If no copy of the source code is required to be filed with the government, then the copyright and/or patent laws are not securing the benefits of that progress for society at the end of the exclusive period. Patents have become similarly lame. Chips get patented with no description language at any level required to be filed. Sigh. Bad congress. Bad bad congress. No cookie. Jeff Walther

15 years, 3 months

Annals of the History of Computing: "bitsavers" is referenced

by aek＠bitsavers.org

> Ye gads... If that's the leading publication on Computer History, it > looks like the market could stand another. Something more along the > lines of the excellent UK magazine "Retro Gamer" perhaps, with > articles written by (and for) normal (if a bit fannish) humans and > lots of pictures of old hardware and stuff. One thing I have learned working at a museum is there is a lot more to the discipline of the history of computing than being a fan and having nostalgia for the subject. I was fortunate to have the chance to have long talks with Doron Swade on what it is like to be a curator at an institution that has existed for hundreds of years, and the responsibility that is involved with that position. There was a very good article on the problems of creating an institution to preserve computing history (in particular, the Charles Babbage Institute) "Arthur Norberg, the Charles Babbage Institute, and the History of Computing" in the Oct-Dec 2007 issue of the Annals, in particular, the collections policy and focus that they created at CBI. "Retrocomputing", nostalga, and eye candy seem to be more of what you are interested in, than the discipline of historical preservation and interpretation, which is where the Annals and other journals on the history of technology are focused.

15 years, 3 months

Annals of the History of Computing: "bitsavers" is referenced

by madcrow.maxwell＠gmail.com

Ye gads... If that's the leading publication on Computer History, it looks like the market could stand another. Something more along the lines of the excellent UK magazine "Retro Gamer" perhaps, with articles written by (and for) normal (if a bit fannish) humans and lots of pictures of old hardware and stuff. You could call it "Classic Bits" or something actually catchy. I'll bet the inhabitants of this list could cook up a better product almost overnight. Mike

15 years, 3 months

Repair of damaged/corroded gold connector 'fingers'?

by ian_primus＠yahoo.com

Recently, I've run across some circuit boards with damaged connector fingers. Some are badly scratched and worn, the gold plating almost gone, and others are actually corroded - the copper has corroded, possibly due to previous damage to the gold plating. The circuit boards in question are the ones in Nintendo cartridges, but the same problem applies to any printed circuit board edge connector. The scratched/worn connectors seem to still work, at least most of the time. The corroded ones wouldn't work until I cleaned off the corrosion. Not an easy thing to do - I ended up resorting to Brasso, a brass polish. Now, this is NOT the thing to use to clean edge connectors! DON'T DO IT! It WILL take the plating off. In this case, the plating was already gone, and the copper track underneath was corroded. Cleaning the corrosion off with the Brasso, and subsequent cleaning with alcohol to clean off the Brasso, removed the corrosion leaving a shiny copper track. The board worked fine, but for how long? How long until the corrosion comes back, or the copper oxidizes? Is there any way to repair or replate fingers like this? Obviously, tinning them with solder would prevent oxidization, but this would make that 'finger' much too thick, and risks damaging the connector it plugs into. (Operators loved to "fix" burnt edge connectors on arcade boards like this, and it works for a while, until you go to unplug and replug it, and the destoyed connector no longer mates with the board correctly.) Just something I thought that others might have an input on - I mean, in this case, these Nintendo cartridges are not worth the effort of any complicated repair, but it raised the question in my mind, and I know I've run into this on computers before. So, any thoughts? -Ian

15 years, 3 months

EPROM erase times and lifespan

by mtapley＠swri.edu

At 12:00 -0600 1/29/09, Jules wrote: >Presumably more expensive erasers do things in-place - i.e. periodically do a >blank-check during the erase cycle? I would be pretty nervous about trying that. Knowing how solar cells work, and having seen cosmic-ray induced latchups destroy chips, it just seems like begging for trouble putting energetic photons onto a powered chip if you don't need to. Of course, EPROMs are cheap, and experimenting might be fun, but if you do this, I'd start with easily replaceable EPROMS. Shutting off the lamp and doing a blank-check, then turning it back on, would work, as would covering the chips with a UV-shade. I don't see much problem with that. -- - Mark 210-379-4635 ----------------------------------------------------------------------- Large Asteroids headed toward planets inhabited by beings that don't have technology adequate to stop them: Think of it as Evolution in Fast-Forward.

15 years, 3 months

Seeking reverse-engineers - Apple II VisiCalc

by aek＠bitsavers.org

> I think typically it just gets misplaced, not lost :-) > I bet it still exists in a lot of cases, but everybody's forgotten exactly > where I respectfully disagree. Once a product reaches end of life, it is disposed of. Unlike entertainment products, which can be resold to the next generation, old software has been perceived as having no commercial value and is discarded either to avoid its availability for legal discovery, when a company is sold, or when they need the space or get tired of paying storage costs for it. I was hoping that working as the software curator at CHM would open more doors for finding old software (esp sources). It has not, with a few notable exceptions like HP. The stuff REALLY is gone. The main source now for old software are the people that worked on it, who kept copies outside of the company they worked for.

15 years, 3 months

Annals of the History of Computing: "bitsavers" is referenced

by evan＠snarc.net

>>> I subscribed to Annals fairly early on and enjoyed reasding it, but got increasingly frustrated by the way articles began to sound like someone's dissertation. The staff, a couple of years ago, began encouraging participation from writers outside their normal circle. For example at the 2007 SHOT SIGCIS conference I gave a lecture about the importance of involving actual end users when writing history, and almost everyone welcomed me into the fold. So, while you're correct about the journal style -- the papers aften ARE chapters of dissertations* -- consider the old mantra of "be the change you wish to see." * PS: That kind of vintage computing is just as important as what happens in cctalk, at VCF, etc. Plenty of room for both. Personally I feel these worlds need to trust each other and work together to advance the topic.

15 years, 3 months

Annals of the History of Computing: "bitsavers" is referenced

by evan＠snarc.net

>>> Or would this bring unwanted attention to the potential copyright issue(s) of the material in question I wouldn't worry about it. The readers of "Annals" are almost entirely academic, not corporate.

15 years, 3 months

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test-drb January 2009