test-drb July 2007

test-drb@ccmp.vtda.org

189 participants
323 discussions

1966 Mag: Build NE-2 Neon Bulb Computer - scan available

by technobug＠comcast.net

On Thu, 26 Jul 2007 21:50:07 -0700, "Chuck Guzis" <cclist at sydex.com> wrote: > On 26 Jul 2007 at 21:39, dwight elvey wrote: > >> Hi >> I have soem tubes made in the 1920's that still have a >> good vacuum. How much longer should I wait. >> Dwight > > Isn't that the whole idea behind a getter? Activated getter works on active gasses (and some of the heavier inert ones also) up to the point where the activated surface becomes saturated. In a well sealed tube, that can be a substantial time. However, it does not work with helium. Helium abhors a vacuum and will attempt to equilibrate its partial pressure inside the tube with that outside - glass and getter be damned. Same goes for HeNe lasers - the helium inside makes for the outside world and the laser goes south. I've been keeping a pair of HP Interferometers going for years by occasionally putting them in pure He for several weeks, all the time measuring the output and waiting for it to come back to spec. If you have an old, well-sealed tube that has gone gassy due to helium, you can rescue it by putting it in a high vacuum for a couple of months... CRC

17 years, 4 months

1966 Mag: Build NE-2 Neon Bulb Computer - scan available

by jfoust＠threedee.com

At 12:23 PM 7/28/2007, William Donzelli wrote: >> Surgistors were very popular in the 50's as either an add-on for TV >> receivers or as part of the original chassis. > >Filled with the finest snake oil available... An old commercial for the Wuerth Tube Saver : http://www.archive.org/details/The_Big_Idea - John

17 years, 4 months

Info requested about ebay seller newbegin-antiques

by aek＠bitsavers.org

> I am looking for background to assist me evaluating this seller. arrogant greedy asshole see previous classiccmp msgs about this scumbag

17 years, 4 months

1966 Mag: Build NE-2 Neon Bulb Computer - scan available

by ajp166＠bellatlantic.net

> >Subject: Re: 1966 Mag: Build NE-2 Neon Bulb Computer - scan available > From: ard at p850ug1.demon.co.uk (Tony Duell) > Date: Wed, 18 Jul 2007 23:54:18 +0100 (BST) > To: cctalk at classiccmp.org > >> <rant> >> I'll make this vintage computer-oriented. How many people still own >> a working dishwasher/clothes washer with an integral computer that >> was manufactured over 10 years ago? When I first saw a dishwasher Maytag washer dryer pair, still in use and working fine. >> with computerized control, my reaction was "What a damned fool thing >> to do--put a computer in the absolutely worst (hot water, caustics, >> steam) environment possible. Now you can't buy them any other way. Automotive is considerably worse. Hot, humid, large temperature changes, power system that runs from 6V worst case to 18V with transients higher and it must work for 5years to be considered passably reliable. >You can see the manufacturer's point. A custom chip is a lot cheaper to >make than a cam-and-contacts timer. They can put the magic words cam and contacts have a well known failure mech, wear. Solution build it more robust, the counter to that is cost. >'computer', 'microprocessor',. 'digital', etc on the panel. And it's >harder to repair if it fails (if a mechanical timer fails, you can fix >it, if the microprocessor fails, you have to buy a new PCB from the >manufacturers, if they don't want to sell you one, you're stuffed). Most vendors want their product to work because if it doesn't there are plenty of competitors with something to offer. Allison

17 years, 4 months

1966 Mag: Build NE-2 Neon Bulb Computer - scan available

by jfoust＠threedee.com

At 07:50 AM 7/27/2007, William Donzelli wrote: >The idea behind the getter is to clean up and gas that might be >trapped in the metal elements during pumpdown. A getter is really not >to clean up gases that sneak in thru the glass metal seals - the >getters just are not that effective, and as any plumber will tell you, >leaks only get bigger. Hmm, that reminds me of a lingering question in my mind. As a kid, I remember harvesting tubes from dead TVs behind the repair shop. Breaking the tube, there was often a ring at the top, U-shaped in cross-section. I seem to remember that they were filled with a powder that reacted with water, fizzing. Am I mixing up this smell-memory with playing with calcium carbide? What were common getter chemicals? - John

17 years, 4 months

Cool Find at Goodwill

by jrkeys＠concentric.net

Yesterday at while at Goodwill looking in the bins I found what looked like a strange calculator. It turns out to be the keyboard (UC-2100) for a Seiko Data 2000 computer watch. Had I knew at the time I would have been on the lookout for the watch, anyway I got the keyboard for 50 cent. Also found a lot of stuff the looks like it came form a Computerland store in FL. I ended up spending close to $40 two large boxes and five very large bags full of stuff to play with. John K.

17 years, 4 months

Apple III Power Supply: Success (I think...)

by derschjo＠msu.edu

Thanks again to everyone offering suggestions for fixing my Apple III's power supply. I opted to do a wholesale replacement of the electrolytics in the power supply, since I was likely going to be removing all of them to test them anyway and there's only a handful to take care of. $9 worth of parts later, the issue seems to be resolved -- the system powers up and runs diagnostics. (Though it keeps cycling, so I don't know yet if that's another problem or normal behavior :)). The only thing I have noticed is that there's a very noticeable "hiss" noise coming from the power supply -- not sure where, exactly. Any ideas if this is normal? At the moment I have only the motherboard & 256k RAM expansion running (no keyboard or floppy drive.) Thanks again! Josh

17 years, 4 months

Reinventing the paper terminal

by silent700＠gmail.com

Well, sort-of: http://blog.scifi.com/tech/archives/2007/07/27/email_typewrite.html

17 years, 4 months

Imagedisk 1.17

by ajp166＠bellatlantic.net

> >Subject: Re: Imagedisk 1.17 > From: "dwight elvey" <dkelvey at hotmail.com> > Date: Sat, 28 Jul 2007 07:28:48 -0700 > To: cctalk at classiccmp.org > > > > >>From: "Dave Dunfield" <dave06a at dunfield.com> >> >> > Ah, the step gremlin. It's an old 765(all!!!) problem. The problem is >>when >> > the step pulse is set to minimum acceptable for the drive it's possible >>that >> > due to internal timing of the 765 it can shorten the step timing of the >> > first pulse by 1 count. If that occurs many drives seek badly and you >>get >> > read or write errors because your not where you thought you were. >> > Note: some old drives due to the lubricants turning to goo will also >>exhibit >> > this type of error. There is one solution, step slower (SRT+1). >> >>A possibility - Christial, try using SR= to set the step rate slower. >> >Hi >One other thing. Ususally one doesn't see this one but on a machine I >put together, using a different processor, on one command I was >able to beet the busy response of the controller chip. It was on only >one command but I don't recall which command. >If the PC is running the bus faster than the 765 is clocking, one can >be too quick. >I recall putting a short delay to make sure the status read was coorrect. >I know it was this because I did an experiment that I'd read it twice. >The second read was OK but not the first. >Dwight Yes, this can be the case as the 765 has a micro inside and it has a finite timing delay and that's driven off the main clock which is usually either 4 or 8mhz. Allison > >_________________________________________________________________ >http://imagine-windowslive.com/hotmail/?locale=en-us&ocid=TXT_TAGHM_migrati…

17 years, 4 months

Sad Story from Denver

by bmachacek＠pcisys.net

Just thought I'd pass on what happened to me this week. Early in the week I got a call from my son who said they had some kind of device that his manager was going to get rid of but thought I might be interested in getting it. He sent me a follow up email that included a couple of pictures of it. It turns out it was a Data General Eclipse computer and looked like an S-140. I called him back and told him I was interested in getting it because it was an old Data General mini computer. His manager wanted it out of the warehouse which they had dropped their lease on right away. They couldn't wait for me to come up on the week end. (I live in Colo. Springs, the unit was in a warehouse in north Denver) I told my son I could get up there as early as Thursday but Friday would be better. I needed to make arrangements at work since this would be about a 3 hour round trip just to pick it up. When I called my son on Thursday to make final arrangements, he said it was too late. The night shift maintenance crew who were cleaning up the warehouse had not been told to leave the computer there for another day. During the night they took it and a couple of old 286s and threw them in the dumpster. Then, being the efficient crew that they were and since they had filled the dumpster, they called for it to be removed. Well by the time my son's manager got to the warehouse that day, sometime after noon, everything was gone. I think this has taught me a valuable lesson which I guess most of us in the "rescue" business learn at one or another, "Don't Wait". I just wanted to share this with the board and say I won't make this mistake again. The next time I hear of an old computer that is available, I'm going to head out that same day and worry about my work getting done later. Bill Machacek Colo. Springs, CO

17 years, 4 months

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test-drb July 2007