I am writing my master's thesis on accelerated life testing and would like
to get a collection of parts to decap and experiment on. What prompted my
study is a failed 7474 dual flip-flop in a PDP-8/E. As I later read (on
here, I believe) was that the 7474s seem to fail in higher number than
other 7400-series ICs. Is this because of a design flaw? I'm not sure
(yet), but would like to find out.
More recently, I saw a 680k 2W carbon resistor that read 1.3 meg out of
circuit. As it turns out, it was in a high voltage portion of the circuit,
and I suspect that electromigration caused its failure over time. Many of
you are probably already aware that carbon resistors tend to increase in
value as they age, though there are a few explanations too for that
behavior, as I understand it.
I would like to tie all of this together by researching older accelerated
life testing schemes, examine how those parts actually fared, and see how
current day models might be improved.
If anyone has a collection of dead ICs (preferably those that have died
inexplicably, and not by extreme overvoltage, for instance), I would like
to talk to you about getting a few. If they are 7474s from Texas
Instruments, ca. early 1970s, even better!
Thanks in advance,
Kyle
I presume I can't be the only one watching this eBay auction in disbelief.
I'm wondering if this is a museum or not. Presumably a private collector
would not have such deep pockets, but you never know!
Over $13k USD and still a little less than 2 days to go!
http://www.ebay.com/itm/Ultra-rare-Commodore-65-C65-DX64-prototype-working-…
I have a friend with a large stash of DG boards which comes from a
collection of stuff he and his company had from supporting Novas. He has
just the stash of boards and would like to get a rig to test them with.
Ideally acquire, but from discussing what he wants to do he would
probably need a minimal set including power, and the front panel to run
tests. I wanted to locats contacts to put him in touch with that might
be able to help him, and you and he can discuss the best way to do what
he is after.
I don't know if he wants to sell / trade all of them, end up with a
working machine or what he may need to do, so he is flexible.
I'll put you in touch with him in whatever manner you feel comfortable with.
thanks
Jim
hello all,
I'm in the process of repairing our 101 but i hit a solid wall finding
out whats wrong with it. are there people with a working copy who could
do some measurements on their copy?
Unfortunately i have no schematic of the electronics, only the mechanics
and PSU.
I have made a crappy video of the scope trace of the delay line input
and i'm very interested in a video of a working machine's delay line. :-)
The video is here: http://youtu.be/llpwjGeldt0
and a partially repairlog is here:
https://hack42.nl/wiki/Repair_Olivetti_Programma_101
als scematics are welcome as well. :-)
--
Met vriendelijke Groet,
Simon Claessen
drukknop.nl
Long shot, but does anyone know of any available disk/tape/paper tape/ROM images for any of the Microdata machines (800/1600) or the relatives (Intertechnique Multi-8/Multi-4, MAI Basic Four BB-II)?
There?s a bit of documentation available - Bitsavers has a bit, and I have some MAI documentation that I?m in the process of scanning. I?m toying with the idea of emulating this machine, but I?m having difficulty locating any software for it.
Thanks in advance.
Ian
> From: Brent Hilpert
> Well, try removing W1 to isolate the output of the xtal oscillator E15
> from inverter input pin E4.4.
Thanks! Too late to try it today, but first thing tomorrow..
It seems like every time you answer one of my queries, I smack my forehead
and say 'That's an excellent idea! Why didn't _I_ think of that!?!?' :-)
> If you're not familiar with them, E15 is an integrated xtal oscillator,
> not just a crystal - the crystal and oscillator logic are both in that
> can
I'm not familiar, so thanks for the tip. Wonder where I'll find one if that's
what's bad... :-)
> Could also (with W1 removed) pull E4.4 hi/lo while watching the
> inverter output E4.16 to see if it responds correctly with the
> inversion.
Since it's a tri-state, I may need to hit the enable somehow. Oh, wait, I
see, it's hard-wired on via a pull-down. (I wonder why they needed a
pull-down? And I wonder what the test point is there for?) And I guess I need
like a 5K series pull-up resistor to +5, right? (Ground I can just tie
directly, right?)
Anyway, thanks again for the help - very, very useful.
Noel
> From: Eric Smith
> The memory controller does have a Unibus port, but the Fastbus memory
> modules are not on the Unibus any more than an RP04 disk drive is on
> the Unibus.
Ah, OK, I guess it all depends on exactly what one means by 'directly'... :-)
I was using it in a high-level architectural sense: there's a 1:1
correspondence between UNIBUS addresses and Fastbus memory addresses; a
UNIBUS read/write cycle completes immediately with the contents of that cell;
etc - all quite different from the RP0x example. IOW, at a very high level,
it looks like other 'memory on the UNIBUS'.
> To a first approximation, the two Unibuses are *always* jumpered
> together.
I seem to recall reading (don't remember where, it was a long time ago) of
some place that actually made use of the dual UNIBUS thing; they hung some
other PDP-11 (don't recall what kind) off UNIBUS B, and ran a primitive
multi-processor. It was some sort of high-speed data acquisition, or perhaps
a real-time simulator - something like that.
Anyone else know of any place that used the dual UNIBUS capability?
Noel
Hello cctalk'ers,
Hopefully this message won't offend anyone --- I recognize that I might,
and I apologize in advance if it does.
As many of you know, I've been in the vintage computing hobby for about
a decade. The first person I met was Sellam Ismail. He helped guide me
as a newb collector of handheld/pocket computers.
Somehow that led to me co-founding MARCH, publishing a 1,000-subscriber
newsletter for a few years, rescuing a mainframe here and there, making
the VCF East into a premier event, and becoming a "talking head"
everywhere from BBC Radio to the Wall Street Journal. (My personal site
is www.snarc.net if you really want to know more ... bring popcorn.)
Now I'm asking for some personal help from the community.
I'm trying something radical: crowd funding, so that I can finally
finish the decade-long project of writing my book about the history of
mobile computing.
You can imagine how frustrated I feel when telling my family "I'm in the
The Wall Street Journal!" but that I'm also dangerously under-employed
(having been spit out of the technical journalism field after 16 years).
It does not compute.
Please visit this link for more information:
http://fundrazr.com/campaigns/3wNcc.
Thank you,
- Evan
> From: Chuck Guzis
> Any more so, than, say, William Gardner Pfann?
Another name I didn't recognize - I knew there was someone who did zone
refining, and that it was critical, but didn't know the name.
> From: Jon Elson
> The XX system?? What's that?
You likely already know of this, just not under this name; here:
http://en.wikipedia.org/wiki/Double-Cross_System
Briefly, during WWII, the British ran the entire German espionage system in
the UK; initially, only for counter-intelligence purposes, but later on, to
actively feed the Germans disinformation.
> Another really great story is the X gerat, (X equipment in English)
> that sent narrow, high frequency radio beams over England.
For anyone who hasn't read it, I highly recommend R. V. Jones' book, "The
Wizard War" - it covers all the various navigation systems (on both sides),
and much more. I can also recommend "The Secret War", by Brian Johnson (the
companion book to a BBC series), which covers that, radar, the V-weapons,
code-breaking, and much more.
> From: Johnny Billquist
>> stored-program (in the sense of 'one memory holds both instructions
>> and data')
> What do you mean by "stored program" then?
Err... :-)
Noel
