test-drb December 2009

test-drb@ccmp.vtda.org

184 participants
226 discussions

by ethan.dicks＠gmail.com

On 12/9/09, Zane H. Healy <healyzh at aracnet.com> wrote: > At 9:55 PM -0800 12/8/09, Chuck Guzis wrote: >>On 8 Dec 2009 at 21:19, Zane H. Healy wrote: >> >>> Okay, this is the first time I've ever had to worry about this. When >>> is it to cold to run a computer? It's 35F out in the garage, and it >>> is supposed to get a lot colder tonight. I just shut the dehumidifier >>> down (to cold to run it) and setup a heater near the computers (and >>> other stuff I don't want to freeze). >> >>It seems to me that Ethan would be the perfect one to answer this. >>35F is probably a heat wave at the South Pole. > > Except I don't think they run their computers outdoors! :-) But we do use outside air to cool them. It's free except for the power to push it around. (Oh... and +35F is never seen at the Pole - the record is +7.5F, and I've personally been around for +7.0F). As for the extreme case, we've had computers malfunction when outside access doors were left open and -80F air came in directly, bypassing the blowers and the louvers. On a day-to-day basis, the room with the 14 racks that was AMANDA (it was shut down earlier this year after a 10+ year run) shed about 35-40kW of heat with indirect access to outside air with some measure of automatic and manual thermal controls (covering up open cable panels and stuffing blankets in hatches in addition to thermostatic controls on air blowers). If we let the room get over about +55F, the high-voltage supplies for the photomultipler tubes would go into thermal shutdown (ultra-dry air at 650millibars doesn't have much heat capacity). OTOH, and more to the point, if we let the room get much colder than about +35F (say +25F or colder), a specific rack of digital hardware that was adjacent to the floor vents feeding cold air to the high voltage supplies would malfunction until the temp came up to the high thirties to low forties. In another location entirely, central Ohio, I used to rent the basement of my mother's typing and typesetting shop. The building was a late 19th C/early 20th C brick "shotgun" commercial space with a former storm-cellar-type access to the basement. As such, cold air poured from the modern back door, down the basement stairs, and into the space I ran PDP-8s, PDP-11s and a VAX-11/730. One of my jobs at the time was hacking PDP-11 assembler on an 11/23. The basement would routinely get to +40F, and sometimes colder if the wind was from the right direction (the water pipes had electric wraps). I couldn't personally stand to work in that environment without a heater pointed at me, but the computers ran fine. The lone device that had problems was an LA-180 printer I used for listings. It worked down to about +45F, but colder than that, I speculate that the rail lubricant got too viscous, because it would blow carriage motor fuses until it warmed up. I quickly learned not to print on cold nights. I'd say that if you keep things at or above freezing, you are probably perfectly fine. Magnetic media is a lot more sensitive than ICs in terms of cold soaking. One thing to watch for is to not power up cold-soaked electronics. The current inrush is likely to blow ICs (the internal bonded wires between the die and the frame, mostly). I've thawed machines that were left in unheated buildings over the winter at McMurdo - ordinary temps around -45F or so. Specifically in that case (ultra cold, powered off), there are known and published "max rates of rise" of temps to minimize the risk of permanent damage >from thermal expansion. A good rule of thumb is about 2-3 degrees per hour. What I did with the cold-soaked computers was to throw them into a lab freezer at -40F for a few hours, then into a lab environmental chamber at -30F that I would tweak up about 5 degrees every couple of hours. When the chamber was up to about +20F, I threw the equipment in a lab refrigerator. The thaw process took two workdays, but 100% of what I treated that way survived (no hard disk - these were floppy-booting diskless PCs that ran from a Novell server). If it gets really cold (+0F, say), I'd bring the disks in the house and leave the CPUs powered off until the garage temps are back around +32F. ICs can be stored down to -40 typically, but not operated at those temps (and especially not put through a power-on cycle at those temps). So that's my experience and observations of cold and computers. Take away from it what you will. -ethan

14 years, 5 months

Happy DEC-20 Day!

by RichA＠vulcan.com

Long live the system that is a major improvement on its successors! Rich Alderson Vintage Computing Server Engineer Vulcan, Inc. 505 5th Avenue S, Suite 900 Seattle, WA 98104 mailto:RichA at vulcan.com mailto:RichA at livingcomputermuseum.org http://www.pdpplanet.org/ http://www.livingcomputermuseum.org/

14 years, 5 months

paper tapes

by aek＠bitsavers.org

did anyone on the list buy these http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220526045578 i'm curious what the interest was

14 years, 5 months

need specs for mag DJ920

by brianlanning＠gmail.com

I just got the monitor for free from craigs list. (and a lead on possible other equipment) Does anyone have the specs for this monitor? Google searches have been fruitless.

14 years, 5 months

Old DEC Power Control 861C

by ba600＠ncf.ca

On December 18, 2009, Normand Fisher wrote: > Hi Mike, > > I have an old 861C (and a 874A) which are very noisy and trigger off > after a short period under load. Would you, by chance, have a copy of > the schematics? > > Or matter of fact any knowledge as to the cause of noise(old capacitors? > ...). Your best bet wouls be to post to Classiccmp Classiccmp mailing list at cctalk at classiccmp.org. Most of my DEC manuals are in Storage tub in the garage. -- Collector of vintage computers http://www.ncf.ca/~ba600 Machines to trade http://www.ncf.ca/~ba600/trade.html

14 years, 5 months

HP91xx controllers (was HP-IB disc drive emulation programavailable)

by shoppa＠trailing-edge.com

Chuck writes: > On 18 Dec 2009 at 23:47, Alexandre Souza - Listas wrote: >> I still think that nothing beats SD. It **will** be the standard >> in two or three years. >I'd really like to know that the things will be available in 10 years >in capacities that will still work what's designed today. Can one, >for example, still get 16MB CF cards? >If all that the unit can handle is FAT32, what does one do when the >only cards available use exFAT? Rather than try to decide on the "one right way" to do things going into the future, don't all of us in fact end up diversifying into what's available now and then shifting up to new interfaces over time as they become proven? I mean, ten years ago I was enamored of MO disks as the "one right way" of storage. It's not that the conclusion was really wrong, but that's not the way the majority of the market moved. (I note that medical imaging still is a big user of MO disks.) Twenty five years ago I might've decided that DEC RC25 carts were the way to go. Hah! How wrong would that decision would've proved to be! What's most astonishing: what used to fit on 10,000 9-track tapes, literally filling an entire moving truck, now comfortably fits on a 1 terabyte portable hard drive that is just a little bigger than pocket sized. That's mind-blowing. Tim.

14 years, 5 months

pdp 8a prom images ??? where ???

by g-wright＠att.net

I just did a search for pdp 8A prom images and could not find any. I'm sure I just looked in all of the wrong places Any help, Looking for 158a2 and 159a2 - Jerry

14 years, 5 months

Fwd: Old Computer to recycle

by jfoust＠threedee.com

Contact the person below ... >To: jfoust at threedee.com >From: Edwina Williams <Wmsedw at aol.com> >Subject: Old Computer to recycle >Date: Mon, 14 Dec 2009 11:43:20 -0500 > >Dear Jeff, > >I have a Maxum 286 turbo computer, which was purchased at 47th Street >Photo in New York in the 1980's. I believe that Maxum was a 47th >Street Photo brand. It comes with a Maxum Enhanced keyboard and Amdek >Video 310A monitor, which has the amber letters. Word Perfect for IBM >is installed and some other programs. There is also an Epson LG 500 >printer, which takes the paper with holes and also single sheets. > >I probably have some of the literature too. > >Although the computer was originally a 286, it stopped working at >some point. I was in graduate school at the time, and spent $900 to >get all my data back and installed on a new 386 drive. So it is now a >386. > >The computer goes right on, powers up, and works perfectly. It also >works perfectly with the printer. This old computer was easier to >write on, and I think I did better writing on it, than the Macbook >Pro that I use now. > >I hate throwing things out that still work, but these have to go. Are >you interested, or do you know anyone who may be? > >Sincerely, > >Edwina Williams

14 years, 5 months

Anyone want a Kontron?

by zudmsc＠earthlink.net

Do you still have it? Michael

14 years, 5 months

Old DEC Power Supplies (861C and 874A)

by icipasla＠gmail.com

I have both an old 861C and a 874A which are very noisy and trigger off after a short period under load. Would someone, by chance, have a copy of the schematics? Or matter of fact any knowledge as to the cause this behavior (old capacitors? etc...). Many thanks Normand

14 years, 5 months

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test-drb December 2009