test-drb May 2014

test-drb@ccmp.vtda.org

171 participants
188 discussions

by bobvines00＠gmail.com

> Date: Tue, 13 May 2014 19:05:03 +0100 (BST) > From: ard at p850ug1.demon.co.uk (Tony Duell) > To: cctalk at classiccmp.org > Subject: Re: DEC ASR-33 "reader run" debugging > >> >> Hi all -- >> >> Finally have the time (and space) to work on my PDP-8/L and its >> associated ASR-33. The 8/L I've had running for a while now, but I've >> only recently taken the time to go over the ASR-33 it came with. It was >> a bit dirty but it's cleaned up nicely and I've got it humming along >> nicely now. (With the exception of the paper tape punch, which is going >> to need a bit more work.) >> >> At any rate -- this ASR-33 was outfitted with the DEC "reader run" >> modification, and it does not appear to be functioning -- with the >> teletype in "Line" mode, the reader switch set to "Start," and with the >> 8/L running the RIM loader the reader does nothing. (It also does >> nothing when set to "Start" in "Local" mode, but I'm unsure if that's >> expected or not...) >> >> With the cover off, if I manually toggle the "trip coil" at the rear of >> the unit the reader runs and the 8/L receives data (and it looks to be >> correct). I've verified continuity between the RELAY+ and RELAY- lines >> from the W076 in the 8/L all the way to the reader run board, and I'm >> measuring 15V between the two. >> >> It's about here where my naivete around analog electronics starts >> kicking in and I'm unsure where to go from this point -- any suggestions >> are much appreciated. > > FGirstly, 'digital circuits are buitl form analogue parts' so I really do > wonder how you can debug a digital system without understanding analogue > stuff. > > But secondly, this is digital. It's a relay. It's a 2-stae device. > > OK, from what I remember about this modification, the relay has 4 > conencitosn. 2 areh coil. 2 are the contacts. When sufficient > currentpasses through the coil, the contacts close. > > The coil is conencted to 2 pins on the mate-n-lock so that the PDP8 can > control it. The cotnacts are wired in series with the reader control > circuit that operates the trip magnet at the back of the typing unit. Be > warned thath the cotncts are in cirucitry that is directly conencted ot > the maisn (pwoerl ine) in most versions, the relay, of course, provides > isolatiuon betwene this and the PDP8. > > Assuming you can idtenify the connecitons, start by conencting a jumper > wire betwene the 2 'contact' terminals of the relay so that it appears to > be operated. Does the reader run now (jn local mode, you don't need to > have the PDP8 conencted). If not, then the problem is not with the the > reder run modificsiton. it might be the reader control PSU. Or the trip > magnet (unlilely) Or the conact wires in the rreder that are operaed by > the manual cotnrol elver or tape out sensor (very liekly). Look at th > Teletype Model 33 docs to figure it out. It's a very simple circuit, > although the official diagrams are designed to give yo a headache!. > > Once you have got the reader to work like that, you now need to test the > relay. Remvoe the jumper across the cotnact terminals that you just > fitted. Now measure the resistance of the coil (everything off, PDP8 > disconencted). Expect a few hundred ohms. If there is a protection diode > in parallel with the coil, check that too. > > IF that checks out, conenct the PDP8 and try to read a tape. What voltage > do you get betwene the coil terminals? I think it's about 15V when the > reader is supposed to be running. If that's not right, the problem is the > relay drive cirucity in the PDP8. Or the cable/connectiors. > > It might be the relay itself, If the coil is beign energised the contacts > may still not be closing. > > -tony > Date: Wed, 14 May 2014 06:36:29 +0000 > From: tony duell <ard at p850ug1.demon.co.uk> > To: "General Discussion: On-Topic and Off-Topic Posts" > <cctalk at classiccmp.org> > Subject: RE: DEC ASR-33 "reader run" debugging > >> > But secondly, this is digital. It's a relay. It's a 2-stae device. >> >> Sure, surrounded by some interesting things like 3 or 4 "thyractors," >> the characteristics of which I don't really understand all that well, >> for example :). > > The Thyractors are essentially devices to limit the back emf produced when the current through a coil > (like the trip coil) is suddenly interrupted (as when the relay contact opens). You don't need to worry about those > for now. > > >> I jumpered a wire across the contact terminals of the relay and still no >> joy. The contacts on the reader control lever are OK (I cleaned those >> thoroughly awhile back) I'll trace through the wiring tonight / tomorrow >> (if I can find the time) and see where I can get with it. > > If you get the 1975 Teletype Model 33 schematics from bitsavers, I think you need to look at page > 8 of the pdf -- sheet FS6. > > It appears the reader trip circuit reduces to the trip coil (the one you worked by hand) and the reader > contacts connected across the mains. So the problem could be a bad trip coil (let's hope not!), bad > connections, or those contacts in the reader. I've had a lot of problems with those in the past, and that's > where I would check first. With the machine unplugged from the mains, pull the reader connector at the > back of the call control unit and see if you can get continuity between the pins of the cable-mounted part > with the reader switch on, tape loaded, etc. If I'm reading the diagram right, that's connector J6, > pins 14 and 15 > >> Thanks as always for the advice; someday I hope not to have to ask dumb >> questions on this list :). (Don't hold your breath.) > > It has often been said the only dumb question is the one that's not asked. I generally go along with > that, although I do feel it's silly to ask a question when you know the chap you are asking won't know > the answer... But that does not apply here. Ask away! > > -tony Assuming that the OP doesn't already have the needed documents and schematics for the ASR-33 & DEC ASR-33 Reader-Run troubleshooting, ere are some links to the docs: http://www.pdp8online.com/pdp8cgi/query_docs/view.pl?id=327 is the "LT33 ASR 33 Teletypewriter mods for PDP-8" which is a 10-page DEC printset of what they did to make the ASR-33 work with the PDP-8s. http://www.pdp8online.com/pdp8cgi/query_docs/query.pl?Search=Teletype&stype… for everything in David Gesswein's scanned document list containing "Teletype" -- the bottom of the results ought to have everything you need. Of course, bitsavers.org probably has all of the same docs too. Bob

10 years, 7 months

Buying something from a museum (was Re: Whats in a straight 8 PDP-8)

by bobvines00＠gmail.com

> Date: Tue, 13 May 2014 08:56:48 -0700 > From: Al Kossow <aek at bitsavers.org> > To: cctalk at classiccmp.org > Subject: Buying something from a museum (was Re: Whats in a straight 8 > PDP-8) > > On 5/13/14 2:26 AM, Dave wrote: > >> what happened to all the stuff from the Boston Museum.? >> > > It went to another museum, EXACTLY what is SUPPOSED to happen with artifacts placed > into a public trust. > > There is a formal accessioning and deacessioning process that museums have to go through > for any artifact in a collection. > > If an artifact is redundant, in poor condition, or is out of scope, the institution can > de-acession something in its collection but the process is not simple, and they have to > make an effort to try to offer it to another museum. > > A collector cold-calling a museum wanting to buy an artifact only irritates the person you contact. > > And just to make it clear, the Computer History Museum has a policy that NOTHING offered or in our > collection is EVER sold. The Computer Museum had a different policy, and had artifacts in their gift > shop, we do not. > > Please DO NOT contact CHM about trying to buy physical objects. Al, Does CHM make and/or sell *copies* of documents and/or software images to collectors trying to restore their own equipment or equipment for other museums? An *extremely* brief look at the CHM site didn't provide an obvious link to that info. Thanks, Bob

10 years, 7 months

Spacewar questionnaire

by wgungfu＠gmail.com

Heya all, Devin Monnens and I are working on a paper regarding *Spacewar!*to be presented at a conference. It's basically tracking the distribution and rate of spreading of *Spacewar!* across mini-computer platforms during the 60s and 70s. As a final part of the research process, we're reaching out to everyone in hopes of increasing the sample amount by finding people that played the game in the 60s and 70s. If that fits you, please take a few minutes to fill out this questionnaire. It'll help us a lot! http://ataribook.com/book/spacewar-questionnaire/ -- Marty

10 years, 7 months

Sharing a Project my 9 year old son and I are working on

by slandon110＠gmail.com

Timmy and I would like to share our progress so far on the new TimmyNet Telco Rack We built this out of cheap lumber from home depot. Upper panel will hold 66 blocks, the wiring, stuff like that, first shelf is the 24 port switch which handles the network, 2nd shelf holds the Wyse Terminal for monitoring the asterisk connection to C*NET, 3rd Shelf is the TimmyNet PBX, 4th shelf contains a Mac Mini which will soon host timmytel.com, 4th shelf is the Asterisk server, bottom shelf will eventually contain back up batteries for everything, so in the event of a power failure, The internet and Timmynet stay on. We've left space for a 1A2 system once we get one here. Hoping to have it all tied into asterisk eventually. Our eventual goal is a modem pool with 8 lines, thatll support PPP and dial in shell access for old computers. We have had the IIGS online over VOIP with a PPP Server running on Linux and it works pretty good at around 14.4. Once it's all up you will all be able to call in with your olden machines and have some fun reliving the experience and the pain of slow dial in lol. My son is 9 years old and loves vintage computers and telephones. His favorite being his IIGS and his C64DTV. But he also plays on others like an Old Mac Performa 631CD. Nothing like a LAN party playing DOOM together over the network on it. He prints banners and signage all the time on the IIGS. Hoping to get him out to a VCF one of these days, I just wish there was one mid summer that was close, that way id be able to take him to it. Anyways heres pics of the project, Timmy has done most of the work including punching down the 66 block and painting https://flic.kr/p/niUEUY https://flic.kr/p/niUoXQ https://flic.kr/p/niUorr

10 years, 7 months

Big Blue IBM cabinets

by sales＠elecplus.com

If he has not scrapped them, I have a fellow in TX has big blue IBM cabinets, reel to reel in top, various configs on the bottom. Are these still wanted out there? Sold strictly as-is, they have NOT been powered on. Maybe some line printers to go with them? No terminals or keyboards. Cindy Croxton Electronics Plus 1613 Water Street Kerrville, TX 78028 830-792-3400 phone 830-792-3404 fax sales at elecplus.com AOL IM elcpls

10 years, 7 months

altair tapes

by cfox1＠cogeco.ca

At 03:46 PM 10/05/2014, you wrote: >ive aquired the collection Good luck with the operation of the vtr. Since the head drum does not rotate with the heads it gets polished and the tape tends to stick to it. Charlie Fox >scotch tape fundamental of digital logic nv3020 format recording a-6-77 >memorex raster formation i220evt-1 i220evt-2 compisit video nv-3020 >scotch gama 11 nv-3020 >scotch current sources logic symbology u551 evt-3 u-551-evt-1 part 1 >nv3020 >sony v32 u551:evt-8, part 1 & most of part 2 ic families recordinga-6-77 >scotch u-519-ev forced extinction c37 34mins >sony v32 u551evt-5 thyristors nv3020 >sony v32 u551evt-4 unijunction transistors 25min nv3020 >scotch u551evt-2 logic symbology part2 > >(think this is medical related as it was last taken out by one of the local >hostpitals) > scotch cip studies un editted views are as follows > -1 gaten multiformate (10 or 12 views) 0000 0000 0000 > -2 ant. cine (all 10 or 12 views sequentially) > -3 anterior e. systale + E. diastole viewed sequentially > -4 l.a.o. cine 5. l.a.o. , E. sys7ole + end distole >sequentially > -5 thallium 3 views, + magnified > -6 polycystic liver 6 views + zoom views > use high contrast on monitor > >scotch c-200:evt-1 part 1 of 2 46mins intro to the radio table - theory of >operation nv3020 2-77 >scotch c-200:evt-1 part 2 of 2 30min intro to the radio table theory of >operation - nv3020 2-77 >scotch u551-evt-6 op amps nv3020 >sony v32 u-551-evt-8 (end) & u551-evt-9, part 1 digital building blocks >nv3020 6-77 >sony v32 u551:evt-9, part 2 digital building blocks nv3020 6-77 > > >what i have found in the box of tapes > > > > > >On Thu, Feb 27, 2014 at 10:03 PM, Adrian Stoness <tdk.knight at gmail.com>wrote: > > > apears a vtr machean has come up with tapes on programes ur altair anyone > > interested in it noticed it on my local buy and sell site > > > > > http://www.kijiji.ca/v-electronics/winnipeg/panasonic-vtr-nv-3020-with-15-r… > >

10 years, 7 months

How to clean DEC Tapes

by marco＠familie-rauhut.eu

Hello all together... i am restorating a DEC TU56 dual drive in the moment. My question is, how to clean the tapes, not the drive. The tapes i have are found in a garage, where they been for about 25 years without a case. Some ideas how to clean them without damaging? Best regards Marco * Englisch - erkannt * Englisch * Deutsch * Englisch * Deutsch <javascript:void(0);>

10 years, 7 months

Looking for parts/info

by ggs＠shiresoft.com

Hi, Now that everything's moved and more or less positioned in my new shop, I'm trying to get some things running again. It's a longer term project but I figured I'd start asking around now. My 2065 (DECSystem-20) is missing some key pieces that I'd like to see if someone in the community has and is willing to sell or let me borrow so that I can try to replicate them (the prints that I have are missing critical bits of information). Here's what I'm looking for: KW20 "master oscillator". This is required when using MF20 memories. I've found a block diagram but that's all I've found out about it. Any help (either in prints or locating one) would be appreciated. BC20C S-Bus cables. I figure if I borrow one or at least get a high res photo (both sides) of the M9006 paddle I can replicate them since I'll need several. I'm already planning on replacing the CPU supplies with modern switchers. That'll do two things: Eliminate the need for 3-phase power Reduce the CPU power consumption down to ~2200W (from the 6000W with the linear supplies). Of course, I still need to do a massbus emulator for the disks but getting the CPU and other bits running first is the priority. Thanks. TTFN - Guy

10 years, 7 months

Tektronix replacement parts

by sales＠elecplus.com

http://www.smcelectronics.com/tekpart.htm This sitehas parts by Tektronix PN. They somewhat expensive, especially since a lot of them are used parts? Cindy Croxton

10 years, 7 months

Anyone need an IBM PS/2 model 50 motherboard?

by jules.richardson99＠gmail.com

My local book store owner also does electronics recycling; I unearthed what seems to be a PS/2 model 50 motherboard earlier. Empty socket where I assume the CPU would have gone, and also missing the fuse (so possibly signs of snafu, or maybe someone just needed it for another project). No RAM, but ROMs are there. Extremely unlikely that anyone needs it of course, but I figured I'd mention it! cheers Jules

10 years, 7 months

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test-drb May 2014