test-drb December 1999

test-drb@ccmp.vtda.org

186 participants
742 discussions

Everyone here should read this.. I thought I'd seen everything.

by dylanb＠sympatico.ca

-----Original Message----- From: Chuck McManis <cmcmanis(a)mcmanis.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Friday, December 03, 1999 3:51 PM Subject: Re: Everyone here should read this.. I thought I'd seen everything. >As with anything, the higher your are the more you see. > >To someone who just sits down in my office and sees the PDP-8/E sitting on >my shelf (sometimes running, sometimes not :-) it seems *impossible* to >find a PDP-8. Then when you start looking you find the fringes of the >"surplus" marketplace where things appear from time to time. Then you find Speaking of which.. it looks like I have some read trips before XMAS. I have a couple of PDP-8As, some 8es, (6 in all I think).. Only reason I am travelling rather than shipping is because every unit has 32K of core..hmmmmmm.core...., some with RK05s and the rest with RX01/2s.. These units are getting harder to find.. I am really working the scrappers and factories.... looks like I might not reach my goal of 120 PDP-8(s-plural) by next fall... but I am flying out to Mr. Gold on Wednesday/Thursday. BTW: Has anyone heard of a PDP-8/A500 ??? what is that? >the liquidators, then you find the scrappers. And then, in John's case, you >find one *huge* scrapper. > >The key is that now we know about them we may be able to save some stuff. > Things are looking good.. just a little slow to start. PDP-8 and other rare mini computers http://www.pdp8.com >--Chuck > >

24 years, 8 months

Tube experts! - I T WORKS!

by dylanb＠sympatico.ca

PDP-8 and other rare mini computers http://www.pdp8.com -----Original Message----- From: Tony Duell <ard(a)p850ug1.demon.co.uk> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Saturday, December 04, 1999 7:57 PM Subject: Re: Tube experts! - I T WORKS! >> >> ITS WORKING!!!!!!!!!!!!!!!!!!!!!!!!!!!!! > >Excellent....!! > >> Special thanks to Tony's idea of hooking up an isolation transformer (6.3V >> but rated to 3000V).. >> >> Okay, I did some of Christians tests and I found that the Transformer indeed >> was arching into the main supply. (I won two of these scopes on EBay). >> >> Here is the funny part.. I rarely go into surplus stores but tonight I made >> an exception. I told the guy at the counter what my problem was and he had a >> box full of 6.3Volt isolation transformers rated to 3000KV > >I wish I had access to suprlus stores like that. The few I know over here >have bits of battered transistor radios and not much else. I ship stuff to the UK all the time. If you have something you are in desparate need of (like that transformer).. please email me. If I see it I can pick it up and ship it. > >> HAHAHAHHAHAHAHAH.. I could not believe it. I bought a few and tried one out. >> The scope now has a perfect trace. On XY the dot is crisp and very stable. I >> have to align the scope.. but will do so after I get all brand new tubes in >> it. > >A word of warning. There is _NO POINT_ in replacing all the valves in a >Tektronix 'scope -- most of them will be fine even after many years of >use (as an example, my 555 has had only a couple of valves replaced since >new). You _will_ cause problems if you replace valves indiscriminatately. >And you will have to do a full calibration (which is not as easy as it >looks). Some valves are probably 'Tektronix Tested Tubes', which are >essentially selected or matched ones. Replace those with ordinary valves >and you'll have a long day ahead of you trying to make it meet the specs. > Okay.. (my lack of tube knowledge talking)... a TV repair guy I know who use to do a lot of tube work told me tubes only last a couple of years. I did not want to have to recalibrate this scope everytime a tube drops out. Also, I will be reselling quite a few of the tubescopes with PDP-8s and don't want the scopes going south a month after they get them. I've ordered the spare but first I'll see how long the scope will last with the ones it has now. Are there particular tubes that will go regularly and should I replace those? >The best thing to do is to run through the calibration making as few >adjustments as possible. If some adjustment won't set up properly, then >debug the circuit. Don't necessarily replace the valve, which may well >_not_ be the problem (I've actually replaced more transistors than valves >in old Tektronix 500-series over the years!). > This one has 4 transistors in it. I am checking the caps right now. >Oh, and don't trust valve testers either. Certainly not simple 'emission >testers', which certainly won't show how a valve will perform in the >circuit. But even a mutual conductance tester, like my Avo Mk 4 won't >necessarily tell you how the valve will work under the conditions used in >the 'scope. The best test for a valve in one of these units is 'Does the >stage perform correctly'. > Yes. >So, buy spares if you want to, but don't replace parts unnecessarily. > Okay. > >> The only reason I don't like tubes is because they are very flakey in old >> mini computers.. From what I have heard from people who use to support them >> every power cycles was a nightmare. I am trying to stick to minis that can > >This may well have been true when you have a _lot_ of valves. But I can >assure you it's much less of a problem in these 'scopes... > >> Okay. >> I know.. What scares the hell out of me is I am hooking this thing up to my >> 8/S.. I am going to put some highvoltage diodes between the 8/S,8I and the >> scope to make sure if the scope goes bananas I don't blow a few hundred >> transistors in the minis. > >Reminds me of what can happen when the CRT in an HP9100 develops an >internal short. It blows transistors all over one of the deflection >boards, and then applies about 220V to the outputs from the processor >chassis. This generally wipes out a number of diodes on the gating board, >and if you're unlucky kills some transistors on a flip-flop board, some >transistors on the ROM address decoder, etc. > My point exactly.. there is no way I am going to let anything over +-10V hit the PDP-8s(plural) >> http://www.vacuumtubes.com/ has all the tubes in stock (all new in the >> box).. It is costing me over $300 for three sets of the tubes though :-( >> >> 6DJ8 Amperex tubes are over $30 each :-( > >Any reason that you think they're defective? Other than they're old >(which is no good reason!). > No, they work fine. I just don't want to have to recalibrate the scope every time one decides to die. If that's not an issue then I will leave them alone. john -- http://www.pdp8.com/ >-tony > >

24 years, 8 months

Scrap value of machines (was Re: ebay feedback)

by edick＠idcomm.com

It's pretty obvious, then, isn't it, that the place to be is on their side rather than bidding against them? Even if you have to pay a little more or work a little more, it's better to be in a position to call the guy up on a free morning and ask whether he's got anything new that you'd like to look at, isn't it? Dick -----Original Message----- From: Christian Fandt <cfandt(a)netsync.net> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Monday, December 06, 1999 9:07 AM Subject: Re: Scrap value of machines (was Re: ebay feedback) >Upon the date 12:58 AM 12/6/99 -0800, Mike Ford said something like: >>>Where can you find out what the gold/aluminum/steel value of a >>>computer at? The obvious solution is to know what a scrapper is >>>willing to pay, and add $10 to your bid. A scrapper will never >>>spend more to buy something than it is worth, a collector will. >> >>Not a good assumption. A scrapper might be willing to spend whatever it >>took to make you never get a winning bid and just go away. > >Yes, an appropriate correlation is that if they can crush computers (before >shredding the carcass) then they can cru$h you. > >Their profits drop corresponding with losses of bids so they're going to >spend extra in the short term to protect their profits in the long term. > >Regards, Chris >-- -- >Christian Fandt, Electronic/Electrical Historian >Jamestown, NY USA cfandt(a)netsync.net > Member of Antique Wireless Association > URL: http://www.antiquewireless.org/

24 years, 8 months

documentation

by lemay＠cs.umn.edu

Two things. First, if the person who acquired a Sun 1 last summer could contact me, I have a set of unused and probably in the shrinkwrap set of SunOS 1.1 manuals that they might be interested in. Also, I might be able to get some old HP documentation. 9000 series 200/300 if i recall (and primarily for 200). These are the old HP's with 5.25" floppy drives that we had back in the early 80's in the computer science department. The problem is, there is a lot of this HP doc, but its all in the sub-basement, and its rather difficult to justify getting a key to gain access to the sub-basement. There is a chance I will get getting the key once more, because we're trying to have a new phone line pulled through conduit down there. I also have a pair of IBM DOS 3.3 in shrinkwrap. These are in the standard book/slipcase style, and say they come with both 5.25" and 3.5" disks. There were also copies of TopView and some IBM network software in the same condition as the DOS, ie, book/slipcase, and shrinkwrapped. Still in the sub-basement though. For myself, I now have 12 wide, and 2 narrow 'placeholders' or whatever you call them, for 19" DEC racks. You know what I mean, those black with yellowish edges placeholders for filling in the spots on the 19" rack that are currently empty... *Big Grin* I'm always open to trade offers... -Lawrence LeMay

24 years, 8 months

Intel Intellec 8 computer?????

by edick＠idcomm.com

24 years, 8 months

DecMate III problem

by yakowenk＠cs.unc.edu

While I'm at it... I've got a DecMate III that doesn't want to play. On power up, it displays "32" at the center of the screen. I've got WPS diskettes, and if they are in the disk drive it seems to glance at them, but still just shows "32" on the screen. If I unplug the keyboard and boot, then it shows "48". Sounds to me like a bitmask; missing keyboard is the "16" bit. Can anyone tell me what the "32" means? If it is a bitmask, can you also tell the meanings of the other bits? Please cc: the answer directly to me, as I've temporarily unsubscribed. Thanks! Bill.

24 years, 8 months

Free NCR tower in Miami FL.

by yakowenk＠cs.unc.edu

I've got a line on an NCR tower in Miami FL. If you are interested in picking up or paying shipping, let me know. Please e-mail to me directly, as I've temporarily unsubscribed (can't handle the volume). Cheers, Bill.

24 years, 8 months

Any GRID experts out there?

by edick＠idcomm.com

This thing has got to be at least 10 years old, but, here goes . . . I was scrounging through some boxes in my basement this morning . . . and found a flat-panel display module, probably monochrome, with the label LM758CXAGNR and the HITACHI brand name emblazoned on it. It has a couple of slide pots hanging from it, each bearing the name GRID in its silkscreen. Is any of you folks familiar enough with devices of this type or familar enough with GRID to steer me onto some information about how one might use this display panel for something useful? thanx Dick

24 years, 8 months

Everyone here should read this.. I thought I'd seen everything.

by dylanb＠sympatico.ca

-----Original Message----- From: Chuck McManis <cmcmanis(a)mcmanis.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Thursday, December 02, 1999 9:18 PM Subject: Re: Everyone here should read this.. I thought I'd seen everything. >>FWIW: If he's under an "assured destruct" contract, and you're buying from >>him, >>then you both can be in a lot of hot water if the wrong people find out. > >OTHOH I have gotten things that were scrapped under "assured destruct" >contracts because the definition of "destruct" is "cannot be reconstituted >to work in the original application." under those terms taking the PDP-8/M >out of a machine tool "destroys" the machine tool because without its brain >it won't work anymore. But the PDP-8 still does :-) > Thanks for that info Chuck. Most of the minis/boards I am pulling out I will try and restrict to University/Factory systems. I don't want to get in any trouble... but.. How the heck does he know which system should be destroyed or not?? (If you saw the place you would understand). If I do get the nerve to purchase a *huge* supercomputer from him (if it comes from a manufacturer) then I really can't resell it... >--Chuck > >

24 years, 8 months

Tube experts! - I T WORKS!

by allisonp＠world.std.com

<Okay.. (my lack of tube knowledge talking)... a TV repair guy I know who us <to do a lot of tube work told me tubes only last a couple of years. I did In TVs where the tubes are low end and not always run at their best operating points that may be true. In Qualtity test equipment that is rarely the case. <not want to have to recalibrate this scope everytime a tube drops out. Also <I will be reselling quite a few of the tubescopes with PDP-8s and don't wan Mechanical shock and power cycling tends to ruin tubes faster. Generally tubes have good lifetimes and can be considered reliable (excluding the effects of heat on surrounding parts) . <the scopes going south a month after they get them. I've ordered the spare <but first I'll see how long the scope will last with the ones it has now. Best to leave be unless there is a direct indication one may be soft. Don't forget with the exception of open filements or shorts from mechanical shock tubes tend to fail slowly and soft. <This one has 4 transistors in it. I am checking the caps right now. Good idea s those (caps) do fail. <>> The only reason I don't like tubes is because they are very flakey in ol <>> mini computers.. From what I have heard from people who use to support <them <>> every power cycles was a nightmare. I am trying to stick to minis that That is true, usually they get filiment failures and those are easy to spot. Power cycles tend to accelerate that. then again I had a tube organ (some 80+ tubes) and only had one failure in 8 years. <>> 8/S.. I am going to put some highvoltage diodes between the 8/S,8I and <>> scope to make sure if the scope goes bananas I don't blow a few hundred <>> transistors in the minis. ???? Why? The scope is an enclosed system that would be hard pressed to emit high voltages back into the system it's hooked to. It's not like the HP9100 in that respect. For the RM503 to do that the HV lead would have to fall on one of the input lines! As I remember the series 8 Display scopes were driven off a pair of D/As and some single bit output to blank the beam. If you have something different I'd like to hear about that. Allison

24 years, 8 months

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test-drb December 1999