test-drb July 2000

test-drb@ccmp.vtda.org

155 participants
521 discussions

by agraham＠ccat.co.uk

I got a reply from one Max Burbank who said only this - "While the Computer Museum has closed, We have incorporated some of it's exhibits and it's mission into our own. For all the details, Follow this link; " and he gave a link to the Computer Section of the Boston MOS, which ultimately came up with nowt to say what had happened. Here's the link: http://www.mos.org/tcm/tcm.html > -----Original Message----- > From: John Honniball [mailto:John.Honniball@uwe.ac.uk] > Sent: 25 July 2000 16:13 > To: classiccmp(a)classiccmp.org > Subject: Re: RE: Vintage prices dropping on eBay? > > > > On Tue, 25 Jul 2000 15:25:36 +0100 Adrian Graham > <agraham(a)ccat.co.uk> wrote: > > Not any more - the Boston Computer Museum closed in July > '99 and some of it > > was 'merged' with the Science Museum. > > Indeed so. > > > I only found out when I went to the > > Children's Museum, which was next to the Computer Museum.....most > > disappointed I was. > > Fortunately, I found out just before my visit to Boston in > September 1999. > > > I mailed them afterwards asking what had happened > > and all they could say was the collection still exists. > > Helpful, that. > > Hasn't it been shipped to California? The Computer Museum > History Centre? Moffat Field? Or am I getting confused? > > -- > John Honniball > Email: John.Honniball(a)uwe.ac.uk > University of the West of England >

25 years, 1 month

Announcing... Rent a wreck

by dogas＠leading.net

Hi Gang, I think I hit on an idea that will help out me and others... Want to try a *old* computer before you buy one? Want to run some old software or access some old data from a computer you no longer have? Want to try your skill makeing some necessary repairs on some vintage computers? Want to try programming when programming was programming? I'm thinking something like a month or two rental, paying for shipping to get it to you. (Next person in line ships from renter(n-1). I'll pay to eventyally get it back to me. This will put machines in circulation, clearing some needed space, and it allow me to better schedule the time I want with any particular machine. Waddayaall think? Would you rent an old machine you haven't found yet? There's certainly a few I wouldn't mind buying time on.

25 years, 1 month

Vintage prices dropping on eBay?

by agraham＠ccat.co.uk

Not any more - the Boston Computer Museum closed in July '99 and some of it was 'merged' with the Science Museum. I only found out when I went to the Children's Museum, which was next to the Computer Museum.....most disappointed I was. All it's been replaced with is a handful of multimedia Compaqs and some iMacs. I mailed them afterwards asking what had happened and all they could say was the collection still exists. Helpful, that. > -----Original Message----- > From: Bob Withers [mailto:bwit@pobox.com] > Sent: 25 July 2000 14:44 > To: classiccmp(a)classiccmp.org > Subject: Re: Vintage prices dropping on eBay? > > > At 12:21 AM 7/25/00 -0000, you wrote: > >> Related note: Anybody on the list know anything > >> on DEC's first product, the Lab Module series? > >> I'm interested in the operating principles of > >> the things. > > > >You need the book _Computer Engineering: A DEC View of > Hardware Systems > >Design_, by C. Gordon Bell, J. Craig Mudge, and John E. > McNamara. Out > >of print, but usually not too hard to find. > > > >It's available online at > > > > > http://www.ulib.org/webRoot/Books/Saving_Bell_Books/Computer_E ngineering/con tents.html > >But this is definitely a good book to have in one's library in dead-tree form. > When I was in Boston a couple of years ago I bought a copy of this book at the BCS Computer Museum gift shop. I don't know for sure if it's new but it certainly looks it. If someone is in the area it might be worth checking out. Regards, Bob -------------------------------------------------------- "If you pick up a starving dog and make him prosperous, he will not bite you. This is the principal difference between a dog and a man." -- Mark Twain

25 years, 1 month

Back to the A1097C monitor again

by pete＠dunnington.u-net.com

On Jul 25, 17:08, Adrian Graham wrote: > Hi folks, > > Assuming I eventually get this monitor working properly with the missing > blue signal whilst looking for bumf about it I found this document that > basically says I can turn it into a PC-compatible 1280x1024 70-75hz monitor > for ~$10. > > http://frauenweb.at/~tina/myhtml/howto.html > > Anyone heard of this one? It seems so straightforward I'll do it..... I've not seen that particular document before, but IIRC that monitor is actually a Sony GDM1960 (or near equivalent), and those were made in various OEM versions for HP, Sun, Dec and possibly SGI, differing mainly in the fitting of the sync sockets. I've seen at least one other account of a successful addition of two caps, two resistors, two sockets, and links to make it work. There's a way to add just one socket for composite sync, too. > The question that leaps mindwards is if it's a fixed freq monitor what > happens to the PC at boot time - do I still see a v.small DOS boot screen Nope :-( And it might not be a good idea to run it at the wrong sync rate for too long. > or > do I get nowt until my GeForce has been fully initialised at 1280x1024? Yup :-) -- Pete Peter Turnbull Dept. of Computer Science University of York

25 years, 1 month

PDP 8/e power wires

by cmcmanis＠mcmanis.com

At 05:00 PM 7/25/00 -0700, I wrote: > > White is "hot", black is "neutral" and green is ground. Most of the screw > > on plugs have a legend on them or on the package. Remember they are > > designed for people who have no training to install. Fred Corrected: >I always thought that the "usual" color code for electrical wiring was >BLACK is HOT, WHITE is NEUTRAL, and green is ground. Am I remembering it >wrong? or is the PDP 8/e backwards from everything else? Nope, I'm the one that was wrong, fortunately several people have corrected me so hopefully Laweence won't get it backward. >'Course, if you soak them in WD-40 long enough, it might not matter. Of course it doesn't matter after soaking, WD-40 is such a great lubricant it allows the electrons to actually slide over to their correct conductor! --Chuck

25 years, 1 month

Back to the A1097C monitor again

by agraham＠ccat.co.uk

Hi folks, Assuming I eventually get this monitor working properly with the missing blue signal whilst looking for bumf about it I found this document that basically says I can turn it into a PC-compatible 1280x1024 70-75hz monitor for ~$10. http://frauenweb.at/~tina/myhtml/howto.html Anyone heard of this one? It seems so straightforward I'll do it..... The question that leaps mindwards is if it's a fixed freq monitor what happens to the PC at boot time - do I still see a v.small DOS boot screen or do I get nowt until my GeForce has been fully initialised at 1280x1024? TIA a

25 years, 1 month

DEC Rainbow Saved

by bbrown＠harper.cc.il.us

I saved a DEC rainbow from the landfill this morning. I have the system, the monitor but no keyboard. Any idea where I can get a keyboard and possibly some software for it? thanks! Since I don't have a keyboard, I don't konw if there is anything on the hard drive. -Bob

25 years, 1 month

PE/Concurrent stuff on the East Coast.

by aek＠spies.com

Thought someone on the East Coast might be interested in this From: Harold Herstein <hiherstein(a)prodigy.net> Subject: Interdata / Perkin-Elmer / Concurrent I'm writing because I have access to a slew of Pekin-Elmer / Concurrent stuff that will be trashed if I can't find them a home QUICK. I don't have time to inventory any of the stuff so I can't tell you exactly what's there. I know that there are 1-2 virtually complete sets of OS/32 reference manuals in binders (most likely circa version 6.3 and 7.2) plus assorted other manuals. There may be hardware reference / maintenance manuals as well. It is a good amount of material, perhaps 4 feet tall (maybe more). I also have a Concurrent 32/30 and a 32/05 that are in 19" cabinets. They worked once upon a time, and I believe most of the boards that are there work, but I tend to doubt that they are functioning as a system the way it is (there may have also been boards removed or swapped with defective onece to keep some other systems working). There are no disks - since these crapped out long ago.

25 years, 1 month

Switching PSU Theory of Operation / Repair Tips & Techniques

by dhquebbeman＠theestopinalgroup.com

> > So, I'd like to eventually repair it. It's a monster, and > > potentially lethal. From poking around with a voltmeter, > > I can see that it chops the AC to DC and doubles the voltage > > to about 280 volts, one positive supply, one negative supply. > > Ok, so it's a switch mode power supply that produces +280v and -280v (wrtg) rails right? > Is this used as a rail to feed low voltage supplies, or are they generated in the main supply. > Or do you REALLY mean that it produces a postive and a negative with 280v across them? > That is what I would expect to see. No, if I measure across the positive and negative, I'm seeing nearly 600vdc. These HT supplies appear to feed the switching section of the PSU. Here's a quote from a former prime engineer (who's been as helpful as his memory permits): : These things are much more complicated than that. Functionally the Line is : directly connected to a special rectifier configuration called a voltage : doubler. It produces rougly 280 volts DC. There is no isolation transformer, : which makes these things potentially lethal. The 280V DC is input to : switcher, which runs the 280V DC through the torroidal transformers to : produce the other voltages. The Big Bridge is to convert the output of the : switch from high frequency (probably about 25Khz) AC to DC. [..snip..] > ****PAGING TONY DUELL**** Tony's aware, and has replied with useful information. Even with a dozen people helping, I'm not expecting to get this repaired over night. If I manage to get it repaired sometime next year, that would be cool. > A circuit diagram would be useful here, but psu's aren't THAT > complicated really. Often the type of fault will indicate where the > problem lies. I can probably sketch the HT portion out, but this PSU includes two rather complex looking boards (although they're only 2-layer) with custom PALs and the like. One symptom I hope leads me to finding the problem is that the PSU has four LEDs onit, 3 green, 1 yellow, the green are status indicators for +5, +12, & -12; the yellow LED is an indicator for the AC. Although the AC feed to the PSU is fine, the yellow LED glows dimly, not brightly, as it once did. The green LEDs are unlit. > I take it the 280v rails you mention are still present in it's non > functional condition? Yes. > That suggests that the mains rectifier is still functional, they don't > 'chop' the ac mains. Uh, being an analog idiot, forgive me if this is a stupid remark, but I thought "chopping" the AC with a rectifier yielded DC; when I measured the ~300v, I was on the DC scale, and I didn't see the needle vibrate like I have in the past when I stupidly tried to measure AC in DC mode. Right now, I'm stuck using this old Radio Shack analog VM; my Fluke is in need of a new LCD display. :-( > Switch mode supplies generally rectify and filter the mains, > and use the resultant 250-350vdc to drive the rest of it. > If you have no low voltage stuff running, and no blown > fuses, it could be as simple as a startup resistor being > open circuit. Look for a high value (~300k - 1Meg) resistor > from the + side of the dc rail to the electronics of the switch > mode supply. These go open circuit at switch on fairly often, > and the supply doesn't get the initial starting pulse it needs. If it matters, the room in which I keep the Prime was hotter than I usually let it get when I have the Prime running (I don't have central A/C, so I have a window unit in an adjacent bedroom and usually use a fan to direct the cool air into the room with the Prime while it's up. That night was hot and I had the air directed instead to my bedroom, so I was running the Prime warmer than I had been, but not, I didn't think, out of spec (site prep guide says 86 degF top ambient temp). So, keeping in mind someone else said that dust is the enemy of a power supply, and being able to tell you that the PSU was indeed dusty inside (the only thing I didn't pull and clean when the system was delivered), and I operated it kinda warm, if the resistor is an item likely to die if it can't dissipate enough heat, then I'll look for that. > ****WARNING**** > These supplies are filtered by one or more largish reservoir > capacitors that can and do store a potentially dangerous amount of > power, they are DANGEROUS even when the unit is off and unplugged until they are > discharged. They may or may not have a bleed resistor across them. I > strongly recommend that you check with a meter after about a half hour > with it switched off to see if they have discharged before you stick > fingers in there or you might get a nasty surprise. I've been measuring across the caps before I touch anything. > If you identify a likely resistor, you will find that you get ambiguous > readings unless you remove it from the circuit. Open circuit startup > resistors are a common fault in switch mode supplies. It's gonna be a bit of a chore to disassemble the PSU, it's in a form factor that allows it to plug into the backplane; separating the supply PCB from the aluminum carrier will be a bitch, and I don't have a lab bench anymore. Damn, I miss my lab bench! > > possible for devices that vary in design not only from > > manufacturer to manufacturer, but wven model to model? > > Never fixed TV sets have you. :^) Emphatically yes. > > Hope this helps. Thanks Geoff! -dq

25 years, 1 month

Fwd: hx-20

by owad＠applefritter.com

Can anybody help him? Tom ====== Forwarded Message ====== Date: 7/25/00 7:27 AM Received: 7/25/00 5:28 AM From: selvyn(a)gold.guate.net (Selvyn Ambrocio) To: owad(a)applefritter.com Hello Tom, I have two HX-20 at my office, but I have a Problem I need read the basic program to make a copy but I cann't. Do you know how read the basic program? With Ctrl + @ I can Break the autoexec, but not respond ====== End Forwarded Message ====== ------------------------------Applefritter------------------------------ Apple Prototypes, Clones, & Hacks - The obscure, unusual, & exceptional. ---------------------<http://www.applefritter.com/>---------------------

25 years, 1 month

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test-drb July 2000