test-drb June 2006

test-drb@ccmp.vtda.org

220 participants
447 discussions

by compoobah＠valleyimplants.com

>> This board is plugged into the two connectors of the last memory board >>in the chain. The cables are then connected to the terminator instead >>of the board itself. >Huh? Perhaps you mean that the way the board connects to >the rest of the machine is *through* the cables (i.e. there >is not some other set of connectors on the board that plug >into a "backplane")? So, *normally* the cables plug into the >memory board but, on the last board, the terminator sits >"between" the cables and the board? >In other words, any solution *must* have 4 connectors on it >(you can't just take two INDIVIDUAL connectors and solder >the RPAK's onto the back of those connectors (i.e. skip the >PCB entirely!) I think that I could probably get away without putting on the pass-through. My IM2 cable has 4 extra positions (IP2 + 1 IM2 are boards installed) I think it unlikely that I will come across enough boards to where I would need the pass-through (would need a FPA + 3 extra IM2s). I (not being an EE) wasn't sure about the seriousness of the crosstalk/unwanted reactance problem on computer busses. The downside to soldering directly onto cables is that there is a separate power feed for the voltage divider network that must be accounted for. Wire-wrap holds distinct possibilities, though. While I'm messing around with this, does anyone else have an IRIS 3k sans terminators? Scott Quinn

18 years, 6 months

display scope options

by chd_1＠nktelco.net

What options would I have for some kind of display scope for my PDP-8/e? I have a VC8/I-like point plot controller that I built last spring and I want a display for it. So far I have used a 100Mhz HP storage scope. But that is my primary debugging tool, so I want something that I can dedicate to the display purpose permanently. The DEC display would be a VR14, but I don't recall ever seeing one of these available. Basically what I need is an X-Y-Z oscilloscope with a reasonably persistent phosphor. -chuck

18 years, 6 months

Repair methods (was Cromemco 3101/Beehive B150 score)

by roger.holmes＠microspot.co.uk

> >> An interesting question. >> >> If you have a module of the same age, I don't see any problem with a >> module swap. > > My main objection, actually, is to _random_ module-swapping, as > suggested > by certain HP calculator service manuals. How you can _know_ the fault > has been cured if you don't know what/where it is is beyond me. With a modern machine with just three or four modules (say power supply, logic board and one RAM module) then you take an informed guess and can swap modules until you guess right, unless of course a module you did not swap causes failure of another module. Then it gets expensive. On my old machine, with 4500 separate PCBs, its out of the question. I have to fault find down to where a signal fails, and then comes the interesting bit with a wire-or machine, which of the OR inputs is dragging a signal down to -6.3 volts? Or is it a short circuit to a supply rail? Sometimes insulating individual signals helps, sometimes it easiest to swap one module at a time until the problem goes away. > >> That's what I do, but my modules are probably logically rather >> smaller. One printed >> circuit board holds one 3 input not-J not-K flip-flop. Another type >> has four And gates. > > But why not repair them? I can't believe they're that complicated > to test > or debug. And I would have thought the components were a lot easier to > find than complete modules. I have scrapped an almost complete machine, so I have many of the commonest modules. I understand digital electronics but I find it hard to get my head around the analogue electronics on the boards. Testing bare components is hard enough but testing them in circuit is tricky, especially if they require half a dozen different supply rails at weird voltages such as -18.0 -17.1, -12.6, -6.3, -4.6, -2 and +12.6. 1960s components which look right are not easy to get new. The resistors all have two green bands where you would expect to find a gold or silver band. Electrolytics capacitors are all orange coloured, and bigger than their modern equivalents. I have not seen any GET872 transistors for sale for a long time, and the last time I saw an OA5 diode in the RS catalogue they were a pound each. So when I run out of modules I will be down to taking components of boards, testing them and soldering them onto other boards. Several of the modules have multiple circuits (e.g 4 AND gates) on them, so that makes it a lot easier. Surprisingly I have had success lately getting big Thyratron valves on e-bay, though they all seem to be on the American continent, which pushes up costs, what with shipping charges, VAT(tax) and handling charges. The thyrotrons are inside the magnetic tape decks were built by Ampex in the States, though the rest of the machine is British, using British components and built like a battleship. Oh, except the Card Punch, which is to an IBM design dating way back to the days when BTM (British Tabulating Machine company) were the licensees for all IBM technology throughout the British Empire. The basic mechanism has been seen with 'Lease-Lend' stickers on it, though the electronics underneath has been radically modified. I will not ramble on any more. > >> When I eventually run low on spare modules I will have to start >> component level >> repair, hopefully being able to make 3 good modules out of 4 bad >> ones. > > That is one reason why you should never throw away a defective PCB. It > might well be repairable later, or you might be able to use parts > from it > to fix another board. Absolutely, though I have sold common ones on e-Bay as novelties/ souvenirs. > OK, 'almost never' -- ISA cards with one ASIC and > not much else don't count :-) No, not much hope there. Roger Holmes. 1962 ICT 1301 mainframe nut (and Apple software author)

18 years, 6 months

DEC hamfest finds

by aw288＠osfn.org

Today's show yeilded one seller with a bunch of DEC PDP-8 cable and Flip Chip scrap - sort of handy, because that DEC coax ribbon cable is not common. Another seller had a LINCscope. This rackmount scope has the oddball DEC LINC-8 custom plugins, but the scope is an RM 564 (I think - the storage scope). Seems odd, although the vendor said the plugins were original to the scope. So the question is - did LINC-8s ever get fitted with storage scopes? William Donzelli aw288 at osfn.org

18 years, 6 months

Raylan Ethernet hubs available

by ddl-cctech＠danlan.com

I have three Raylan modular 10Base hubs available with many 10BaseFl modules, ~4 10BaseT modules, and a couple of 10Base2 modules. If you don't know what these are (and possibly if you do :) you probably do not want them. This appears to be a picture of one, though I'm not sure why they are showing such old equipment: http://www.fiberopticsonline.com/Content/ProductShowcase/product.asp?DocID=… As usual, price is $0 plus shipping... Dan Lanciani ddl at danlan.*com

18 years, 6 months

DN10000s

by g-wright＠worldnet.att.net

Message: 9 Date: Sun, 11 Jun 2006 00:32:44 -0700 On Jun 10, 2006, at 6:04 PM, Scott Quinn wrote: >> FAA had, I think, some in-house S/W on their Apollos- what did >> Boeing use on them? > > >>They ran a document publishing system built loosely around Interleaf, >>>or at least that's the application that prevented them from getting >>>rid of their Apollos long ago. >>ok >>bear -- As far as I know Boeing is still using Apollo's in some places. They where one of the largest users of Apollo's and had large amounts of there own software running on them. Most of this was for Airplane testing and development. This is what kept the Apollo's around for so long. Someone in the Seattle area had mentioned that they needed a keyboard for an Apollo. Just contact me off list. I still have a few. - Jerry Jerry Wright g-wright at att.net

18 years, 6 months

Vintage computer diagrams scanning

by RLAAG＠PACBELL.NET

I was wondering about getting some of the diagrams and text documentation scanner and made available for those needing it... I have stuff for Computer Automation Alpha-16 and LSI-2 with the diagrams being on 11 X 17 sheets... I called around and it seemed that they wanted $5 a page, and this just sounded like a rip off... Al Kosso mentioned a while back that he might help do this and i was wondering if the 11 X 17 pages are hard to do or if they can be done on his scanner or another??? I am in so. cal. in Riverside...

18 years, 6 months

by chrism3667＠yahoo.com

dude...I wasnt taking personal at all. I was just pointing something out. It happens to me alot! LoL. Maybe it has something to do with all those banana peels... --- cctech-bounces at classiccmp.org <jwest at classiccmp.org> wrote: > Chris M wrote... > > sorry, but it always seems to be the person who > > responds to name calling with name calling who gets > > the reprimand. > > Well then officially and in plain sight, let me say that I post a reprimand > while reading a thread and it may or may not be the primary offender. > > I don't read every thread on the list. It's possible I stumble across > something after several things have gone on already. It's a whole lot easier > for me to just shout out "don't make me turn this car around..." than it is > to go back and figure out who started it and who was the "worse" offender ;) > > Loosely translated, don't take it personally :> > > Jay > __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

18 years, 6 months

DN10000s

by aek＠bitsavers.org

> Apollo should have open-documented their stuff. Yup.. A huge problem for Apollo historical preservation. I don't even know what might still exist inside HP for the early stuff.

18 years, 6 months

DN10000s

by compoobah＠valleyimplants.com

>>> Apollo should have open-documented their stuff. >>Yup.. A huge problem for Apollo historical preservation. >>I don't even know what might still exist inside HP for the early >>stuff. >Absolutely nothing, and that's confirmed. Boeing was the last >existing Apollo customer with systems still in production until >September of 2005. The final three years of which all hardware >maintenance was performed in-house, scavenging parts from >decomissioned machines. All leftover parts cleared surplus by >CYE2005, which is a pity as I owed DOMAIN keyboards to a few folks >and now I am not sure if I'll be able to make good on it. >I think the FAA were the second-to-last existing Apollo customer. Not >sure when they finally retired their last systems, but it was years >before Boeing did. FAA had, I think, some in-house S/W on their Apollos- what did Boeing use on them? Scott Quinn P.S. - I got one of those last-dump Apollos- there weren't any keyboards or mice at Boeing, but still several 425es. I was kind of wondering if they used them as Apollos or HP 9ks. Now I know.

18 years, 6 months

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test-drb June 2006