B&S Engine starts but won't run

wrote:


The Ph.D. project manager had been an instrument designer at Keithley, where he designed a meter that could detect 60 electrons per second.
These were custom circuits on ~2" x 4" cards that fit in the test head over the wafer. The current meter resolved to 100 femtoAmps over a common mode input voltage range of 0 to 100V. The only suitable coax and reed relay insulation with low enough dielectric absorption was special teflon foam tape from W.L.Gore.
That company built Analog Devices' production-line parametric testers, the machines that confirm each part meets specs, and had an arrangement to get enough of their hand-selected highest-performing op amps to build more sensitive and accurate analog circuits than anyone else. Most of them went back in testers for AD.
When Schlumberger bought the company the competitors sued with the FTC, claiming it was "unfair" that the biggest company in the industry now owned the technology leader. The distractions of the lawsuit destroyed them.
--jsw
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    O.K. My first thought was at least partially right. :-) (A small part of the industry -- down to counting electrons as they wander past. :-)
    I remember that we had one of Keithley's picoammeters in a Faraday cage with the controls remoted to the outside with Teflon shafts. I forget what it was measuring, but they were sure careful about stray fields.

    Impressive.

    Eventually, that should saturate, and more make it out to the rest of the industry. :-)

    Ouch!
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wrote:

The hand-selected ones had different part numbers that weren't in the catalog. There's always a bell curve distribution. We got the upper sigma for input bias and offset current, Radio Shack was rumored to get the lowest one. Other parameters didn't matter to us so maybe some audio synthesizer company got the ones with the highest frequency response. Our machines didn't check for that, only the guaranteed-by-test data sheet parameters, though I've measured Bode plots on the bench. As long as the circuit settled to the required accuracy within one millisecond we were happy.
That was for analog measurements. The digital memory chip testers sent out address and data at 50MHz, state-of-the-art in the early 80's when the test vectors had to be generated in the main rack and sent out long cables to the test head.
I bought a batch of Chinese Schottky solar panel isolation diodes that all are slightly below the reverse voltage leakage spec at room temperature, and worse above it, as though they were the rejects from a production tester.
In class they treat op-amps as ideal devices. I was exposed to the nitty-gritty of all the ways they aren't, and how to measure the discrepancies. http://www.analog.com/library/analogDialogue/archives/45-04/op_amp_measurements.html
--jsw
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    Of course.

    I believe it. :-)

    Reasonable -- for what you were doing.

    Ouch! Perhaps a buffer near the test head which could be pre-loaded from the computer, and then triggered to spit it out at the RAM on command. If the tests were repetitive enough, that would minimize the total bandwidth sent to the test head -- and local checking for errors and only spit the errors back to the computer to minimize the bandwidth the other way.
    I remember long ago when I worked for Transitron -- one of the products was what they called a "ref-amp" -- a potted transistor with a Zener and forward diode (called a Stabistor, and selected for temperature behavior) in series with the emitter. The transistor B-E forward drop, that of the diode and of the Zener were matched by a minicomputer measuring large batches of each device at three temperatures -- -50C, +50C, and +150C, and punching out a deck of cards -- one per device. These went to the mainframe to be sorted to get the minimum temperature sensitivity. The devices were in multi-device carrier submerged in a bath of silicone oil -- a different one for each temperature.
    I remember when we got a few of them back from a customer, and I had to test them through the whole temperature range. At the -50, the other silicone oils set up to a gel, and at the +150, the low-temp one boiled, so we mixed about 50-50 of high and low temp oils. Put the DUT in the bath, toss in a handful of dry ice chunks, and wait until it got below the -50, and then turn on the hotplate under it and take a reading at ever 10 degrees C on the way up. Then turn off the hotplate, wait for it to cool down, swap in the next device, and repeat. (Yes, the devices did go out of spec between the three points at which they were tested before assembly. :-)
    Anyway -- someone else wandered into the room, and tossed in some dry ice while the bath was still quite hot. It boiled like mad (into the pockets of CO2 in the liquid), with vapor spilling over the edge of the really large beaker, spreading out over the bench, and curling in to the still hot hotplate coils.
    FWOOF!
It was interesting seeing the silicone oil vapor burn. We had a CO2 extinguisher handy, and put it out, and were able to continue with the tests. One thing which I had not expected was that there was fine white sand over everything, from the burning Silicone oil. :-)

    Sound adequate for the purpose, at least. :-)

    Yep. In class, the input impedance is infinite, the output impedance is zero, the open-loop gain is infinite, balance between inputs is perfect, and no capacitance anywhere to delay signal changes. For most applications, you can get away with treating them as being like that -- but of course they are not.
    My first exposure to op-amps was the plug-in modules with two tubes which were used as part of the Beta testers on the transistor production line. I had no idea how they worked at the time, so the schematics rather puzzled me. :-) Trying to remember who made them, and I *think* that it was Philbrick -- who also made ones with discrete transistors in little metal bricks.
    I first learned how to use them from the Burr-Brown application booklet.

    Enjoy,         DoN.
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wrote:

That was the era of the 2102 1K x 1 and 2141 4K x 1 static RAM, and welding-sized power supplies for big (64K) banks of them. They had samples of 6116 2K x 8 and 6264 8K x 8 CMOS static memory but IIRC they weren't fast enough, so I was given them for my wirewrap 8080 computer. At first it had 256 bytes of memory.
DRAM was still being developed. A few years later I designed an ASIC controller for it.
When they closed they had been trying to design ceramic hybrid pin drivers to fit in the test head with some pattern memory on them.
The test head contains the electronics that have to be close to the probe card that contacts the IC bonding pads to test it while it's still on the wafer. The head can't be too large or heavy to position within a thousandth of an inch. It's the smaller box on the positioner on the purple machine. http://aesrep.com/STArATE.php
I've never been in a clean room to see these machines in use. The wafer probing I did at Unitrode was all individual setups with standard lab test equipment, with no dust control since we were testing only prototypes. Wafers are brittle, but otherwise exposed ICs are surprisingly resistant to damage.
--jsw
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wrote:

If you have a Dell with the Diagnostic partition or the Pre-Boot System Assessment in the BIOS you can see how complex, huge and slow memory tests can be.
--jsw
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    Nope -- No Dell. (I don't use Windows, FWIW.) But there was an intersting memory test published in the manual for the Motorola MC6809 CPU. It was a position independent program -- except for the checksum on the program itself. Once it is running, you could ask it to relocate itself and run in the memory just checked, so it could check the memory it just left. :-)
    As it turned out -- running it in a chunk of memory was a better test of speed problems than running it *on* the memory in question. There was one board which had problems with rapid sequential accesses, so running in that memory would crash the program, but running on (that is, checking) that memory would never find a problem. It could not give detailed information on the particular bits failing, but it was enough to motivate me to retire that board and wire-wrap a board using 6108s instead.
    And -- with today's memory size -- exhaustive tests can take forever -- walking bit or other tests. :-)
    Enjoy,         DoN.
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    There were 8 of the 2102s in my Altair 680b (kit computer based on the Motorola 6800, not the Intel 8080 which the first Altair had). While not too fast, they were still a lot faster than the machine, simply because they pulled the clock down to 500 KHz instead of 1 MHz (the max for the CPU chip) because they used 1702a EPROMs for the monitor, and did not bother implementing a stretchable clock for the system, so it had to be slowed down to the 1702a's speed. Otherwise, it could have been 1 MHz -- or later, 2 MHz for the 6800B, which I wire-wrapped into a replacement CPU card for the SWTP 6800 (moving the baud-rate clock off the CPU board, because the original of that system had something like a 768 KHz CPU clock to divide down to match baud rates. :-) (I was also using the 6116s in that system at its end of life. A lot more reliable than the dynamic RAM chips which were used on some boards. So -- the replacement CPU board was wire-wrap too.

    Four of the 6264 chips would have saturated the address space of the 6800. :-)

    I had fun diagnosing a problem with some Multibus RAM cards in my first unix box -- based on the Motorola 68000. Turned out to be a problem in a delay chip used to make the different clock pulses for the dynamic RAM.

    Makes sense.

    Sure -- keep the waveshape clean for pulses fed to the chips, and minimize delay for what comes back to test.

    A pity that doesn't give closer views.

    Brittle, yes -- and static sensitive -- especially memory chips. (For that matter, memory chips are also sensitive to illumination levels.) I remember hobby articles using RAM chips without covers as image sensors. :-)
    Enjoy,         DoN.
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I scratch-built my wirewrapped computer to learn how to design and program them instead of to use it, though the editor / assembler I wrote for it worked well enough to compose and print my resume. The I/O circuits were simplified versions of those in the IBM PC and the RS Color Computer.
It had a minicomputer switch panel with enough circuitry to write and display memory and vary the CPU clock, down to <1 cycle per second for debugging. At first I had to toggle in a boostrap loader that read in the monitor program (a mini OS) from a Teletype tape.
That got old very quickly so I added NiCads to keep the 6116 alive. As more slightly used sample RAM became available I installed more 6116s and rewired the lowest socket to take a 2816 EEPROM. We had been experimenting with adaptive algorithms to program them rapidly in production.
Eventually my growing code collection crashed into the 8080's lack of relative jumps and I stopped working on it. By then better CPUs were coming along too rapidly to know which to upgrade to. I would have bet on the 6809, 68020 or 8086 instead of the 8088 that soon dominated in the IBM PC. The company chose the DEC LSI-11 and then the TI TMS9900.
At later jobs the TMS320 DSP family was THE choice for fast dedicated systems, an early color scanner and Mitre's digital radios. The DRAM controller I designed was for the scanner, to prioritize competing memory requests from the A/D, DSP and the IEE488 controller and then try to fit in refresh cycles. During a scan the data stream from the A/D converter couldn't wait, but it effectively kept the memory refreshed by hitting every row repeatedly.
https://en.wikipedia.org/wiki/Memory_refresh " A normal read or write cycle refreshes a row of memory, but normal memory accesses cannot be relied on to hit all the rows within the necessary time, necessitating a separate refresh process."
Actually DRAM holds data for several seconds without a refresh. If you have a $100,000 IC tester to play with you can write a pattern and then read it after 1 second, then repeat for 2 seconds, etc. I saw the first bit drop out at 2.
The color printer & scanner company was also driven under by a lawsuit. I barely dodged having to testify because I knew that the thermistor circuit I used which the plaintiff claimed as their 1980 trade secret was in my 1978 car.
--jsw
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    [ ... ]

    The CoCo had a much better choice of CPU than the IBM PC. -- just not enough hardware to support the fancier disc controllers. :-)

    O.K. Somewhat similar to the Altair 8800 (Intel 8080 CPU). The Altair 680b had a monitor program in a single 1702a, so you did not have to load a bootstrap from front panel switches -- unlike with the Data General Nova which I used for a while at work. :-)
    Later -- I designed a specialized 6800 based system at work for an experiment with imaging and the effect of noise patterns on usability of the images. It generated range specified pseudo-random noise patterns (both offset and gain) and stored them in special wire-wrapped memory cards (more 6116s). Then the image clocked a different port to the memory to put the gain and offset on the same pixel each time through the image. (Only project that I was actually in control of which had co-workers doing some of the wire-wrapping for me, once I verified the first memory card to work. :-)
    Later -- that got used for an additional experiment. Image was formed with a slow scanning mirror bouncing it -- and the display had the offset applied to it so the image stayed stable, but the noise patterns moved from side to side. That made a *big* difference in the usability of the image. It was rather like driving past a picket fence and being able to see what is beyond it, unlike when stationary. :-)

    At first, the code got loaded via the emulator probe from a Tektronix microprocessor development lab, but that was a bit awkward, so I wire-wrapped another card to program 2716 EPROMs, since hand keying it all in to a Prolog PROM burner was error-prone. :-) I added the burn program to the control program I wrote for it, so subsequent updates to the program were easier.

    Yes -- the 6809 would have been a good choice before the jump to 16-bit words or larger. It has nice relative jumps and branches to anywhere in the address space. With the 6800, if you need a long jump, you code that and a short branch around it on the opposite sense of the test. Really a very nice regular instruction set. Same, of course, for the 68000 family. The 8086 and 8088 were stuck with that weird segmentation scheme to allow code written for the 8080 to be assembled and run. The 6809 was an upgrade of the 6800, but the 68000 was a clean jump to a new architecture. I was working on designing and wire-wrapping a 68000 based system when I stumbled on a 68000 based v7 unix system at a hamfest.
    The real indication of the power of the 6809 was the Microware OS-9 operating system. Position independent and re-entrant code, and a multi-user multi-tasking OS running in 64K of address space or less. (And OS-9 Level 2 which required memory mapping hardware, but could make use of the full address space that the 68000, or later the 68020, offered.
    The TI 9900 was an interesting CPU -- based on their 990 minicomputer -- but rather clumsy, especially in the initial implementation. Having 16 16-bit registers which were mapped into memory, so you could get a fresh set of registers by simply changing a pointer was nice -- until you realized the number of cycles that it took for any register operations. Later, they modified it so the registers had copies in the CPU chip itself, and a BLWP (Branch and Load Workspace Pointer) copied all of that region of memory into the on-chip registers, so any access to the registers was a lot quicker -- unless you changed the contents, at which point they still needed to be written out into memory.
    The other thing was the weird I/O approach. It had an I/O space 4K long (IIRC), and you could do any output or input length up to 16 bits, but you needed a clock cycle for each bit, making it rather slow for even floppy disk I/O -- unless you gave up on their approach and used a memory-mapped approach so you could get all 16 bits in a single operation.
    I don't think that there is anything using the TMS9900 instruction set these days. :-)

    O.K. No experience with the DSP world, though I was interested by the Motorola one, and still have the manual somewhere. :-)

    A separate refresh process -- but it can be at a board level, so when nothing is accessing that board, it can be doing its own refresh operations.

    Any idea how temperature sensitive that might be? I would expect shorter times near the top temperatures at which it could operate. (Faster leakage through the semiconductor insulators. :-)

    Ouch! You've had them following you around. :-(

    Reminds me of a patent claim and lawsuit for a particular bit of computer design. I read about it in comp.unix.wizards (IIRC) and it sounded familiar, so I went into where I thought that I had read about it, and found a description in the manuals for the CDC 6600, which predated the claimed invention date, so there was prior art.
    Also -- we (a government lab) got a demand that we go through all of our oscilloscope probes, looking for ones which might infringe a patent that Tektronix had. (So -- we had to list everything that we found that was not branded by Tekronix -- including a couple of examples of a BNC, some RG-58 coax, and a resistor soldered to the center conductor. Obviously lab-made. :-)
    Enjoy,         DoN.     
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DoN. Nichols wrote:

http://www.philbrickarchive.org/ has the history of their op-amp, the GAP/R Model K2-W. I had one in my collection, but I don't know what happened to it.
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Subject: Spelling Lesson

The last four letters in American.........I Can
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    That's it!
    Thanks,         DoN.
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wrote:

TFF! I laughed so hard at that one, I'm in tears. Too bad he didn't catch it all on video, from both angles. I'm sure it would have gone viral on YouTube.
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wrote:

I would have spewed coffee on the keyboard and laughed myself silly, but I backed off from such pranks when I found out that a fragile neurotic could believe that they had snapped and were hallucinating.
For homework my wife programmed the Cylon red eye on the data register display of a PDP-8.
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    [ ... ]

    [ ... long description snipped ... ]

    Now -- there would never be a fragile neurotic working with computers, would there? :-) (Other than the user who took a fortune cookie program output personally -- just because it happened to be for a Libra, and she was a Libra. :-)

    Ah -- the PDP-8 -- so much hardware for so little capability. :-)
    Enjoy,         DoN.
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On Sat, 3 Sep 2016 10:00:03 -0400, "Jim Wilkins"

Humanity is fragile, innit?

Complete with sweep/scan sounds? Cool! <g>
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Every day I remind myself that my inner and outer life are
based on the labors of other men, living and dead, and that
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    [ ... ]

    [ ... long description of hack snipped ... ]

    Too early for YouTube. Arpanet was just getting started. A couple of years later, the computer center got a "butterfly" to enable interfacing to Arpanet -- which later became the internet. I had fun downloading and compiling useful programs from the original Simtel-20 site with that.
    Enjoy,         DoN.
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wrote:

Yabbut, I meant that had he saved it to video, it might still be around and have been put on YouTube to go viral.
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On Wed, 31 Aug 2016 19:34:01 -0400, snipped-for-privacy@yahoo.ca wrote:

So you're a huntin' pecker, eh, Gerry? Oops, I meant hunt and pecker.
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While we have the gift of life, it seems to me that only tragedy
is to allow part of us to die - whether it is our spirit, our
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Larry Jaques wrote:

Boys weren't allowed to take typing when I was in school, until my senior year. I wasn't about to drop a shop class, to be in a hot classroom with a 70+ year old screeching woman teacher. You could hear her to both ends of that floor.
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