Rili - Science...If you've everhadto troubleshoot a digital circuit withtraditional analog...

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atALTH~~~~ A ts .itn §AtNOV 2 73 2S ovIcm)em 1973 Vol. 182, No. 4111 . 0 7i-. L<5-0t Rili M//~ 30 >.'i>Y<4 / / / ;// 03 7 mrams; a~~~~

Transcript of Rili - Science...If you've everhadto troubleshoot a digital circuit withtraditional analog...

Page 1: Rili - Science...If you've everhadto troubleshoot a digital circuit withtraditional analog instru-ments, the experienceprobably convinced you there shouldbea better way. Takevoltage

atALTH~~~~ A ts .itn §AtNOV 2 73

2S ovIcm)em 1973

Vol. 182, No. 4111

. 07i-.L<5-0t

RiliM//~

30>.'i>Y<4 / /

/ ;//03 7

mrams;a~~~~

Page 2: Rili - Science...If you've everhadto troubleshoot a digital circuit withtraditional analog instru-ments, the experienceprobably convinced you there shouldbea better way. Takevoltage

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Page 3: Rili - Science...If you've everhadto troubleshoot a digital circuit withtraditional analog instru-ments, the experienceprobably convinced you there shouldbea better way. Takevoltage

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11,1,n MEASUREMENTECOMPUTATION changing things for the better

How to live more comfortablyin an increasingly digital world.In the continuing technological evolution,television sets, automobiles and even kitchenappliances are beginning to use digital elec-tronic circuits once limited to computers.

In the digital world, it's the merepresence or absence of electrical pulses - ortheir on-off pattern in time - which conveysthe information needed for computation, con-trol or communication. In analog circuits, thedata conveyed comes from the amplitude or rateof change of electrical signals. Because of thisfundamental difference, the many benefits ofdigital electronics are accompanied by a new setof problems for designers and troubleshooters.

If you've ever had to troubleshoot adigital circuit with traditional analog instru-ments, the experience probably convinced youthere should be a better way.

Take voltage measurement. In an analogcircuit, it's important that you know the abso-lute voltage of a test point, whether it's between5.015 and 5.018 V., for example. But in adigital circuit, the important thing is to knowthe logic state of a node, whether it's above thethreshold voltage and therefore a logichigh, or below the threshold voltage andtherefore a logic low.

Time presents another problem. Abso-lute time measurements are unnecessary indigital systems. Things don't happen after acertain amount of time has elapsed but ratherafter a certain number of clock pulses, regard-less of their duration. The circuit troubleshooterneeds to know, for example, if a data bitoccurred 1024 clock pulses after an event-and couldn't care less if it took .509 ms toget there.

Furthermore each IC in a digital circuithas 14 or 16 leads and you may need to knowwhat's going on at all the leads simultaneously,not just at two or three input and output leadsas with the components of an analog circuit.

Having come up against these complica-tions in our own manufacturing and serviceoperations, we've developed a family of instru-ments that complement the traditional oscillo-scopes, DVMs and counters for digital circuittest and analysis. As you read on, you'll learnhow these instruments provide easier, faster

:4. A

and more accurate solutions to digital problems.

The IC troubleshooterspinpoint the circuit problem.Used singly or in combinations, theseinstruments are unique in their ability to detectin-circuit logic failures, analyze the cause ofthe failure and isolate it to a particular IC node.

When the logic clip is attached to anin-circuit IC, it indicates on a bright LED dis-play the logic states at all 14 or 16 pins simul-taneously. The clip automatically locates thetest IC's ground and power supply, borrowspower from it and thus requires no cable con-nections of any kind. $125.*

The logic probe indicates the conditionof a specific IC node and tells you if it's high,low, bad-level or inactive. It captures singlepulses as narrow as 10 ns and stretches them toa bright blink at the probe tip. $95* forTTL/DTL or high level logic. $95* for ECL.

The logic pulser teams up with the probeor clip for stimulus-response testing. Typically,you use the pulser to inject reset, shift andclock signals into a circuit, and then observethe effects at a particular IC with the clip, or atan individual node with the probe. The pulser'soutput is high enough to overcome "clamped"IC outputs yet its pulse is brief enough to pre-vent circuit damage. $95.*

The logic comparator is a self-containedfunctional tester that borrows power and inputsignals from an in-circuit test IC. It instantlycompares the logic states of the test IC andthose of a reference IC of the same type. Differ-ences are displayed on one of 16 LEDs. Evenbrief or intermittent failures are detected. $375.*

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The logic analyzersdetect bit-stream problems.With the instruments described so far, youcan determine the logic state of a digital circuitat one particular clock cycle. But if you wantto know overall circuit performance and com-

pare it against truth tables or system timingdiagrams, you have to learn how the processionof logic states changes with each pulse of thecircuit clock.

Two new HP instruments greatly simplifythis task. Both extract from long bit patternsthe essential information required by the digitaltroubleshooter: for each successive bit time, isthe data (logic state) high or low? The Model5000A captures 32 successive bits from twoparallel channels and displays them as logichighs or lows on LEDs. The Model 1601L doesthe same job for twelve parallel channels at atime and displays 16 successive bits in eachchannel, expressed as l's and 0's on a cathoderay tube.

Both instruments can operate at speedsup to 10 megabits per second, capturing thedesired portions of long, non-repetitive bitstream with great flexibility and complete re-peatability. You can trigger the display - andtherefore the bit-capture - to occur after asingle unique event or multiple simultaneousevents. You can dial the precise amount of delayyou want and thus move the display windowforward from the trigger event as many as lOclock pulses (105 for the 1601L). With negative

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delay, you can even look backward in time. Youcan, for example, trigger the display on a faultcondition and see the bit pattern that led toand caused the fault.

The 5000A and the 1601L are compatiblewith all digital logic families. 5000A, $1900,*1601L, $2650.*

Automatic circuit tester mass-tests complete digital assemblies.When you're dealing with large numbers ofdigital circuit assemblies, manual testing of anysort can be prohibitively expensive or evenimpossible. This is where the Model 9560B/DDigital Circuit Test System fits in.

This new modular system can simul-taneously test all the pins of a complex digitalassembly at rates as high as 22,000 truth tablepatterns per second. Results can be displayedas a simple pass/fail, or extended to specificfault diagnosis using logic probes according tocomputer-generated instructions. Test pro-grams are written in easy-to-use ATS BASIC;a software package for computer-aided genera-tion of test programs is also available. Pricesstart at $53,900.*

Our digital capabilities don't stop at theend of this page. The range of HP digital testand analysis includes digital communicationstesting systems as well as digital pulse gener-ators. For more information on all of the abovewrite to us. Hewlett-Packard, 1507 Page MillRoad, Palo Alto, Calif. 94304.

*US Domestic Prices Only. 00318

* Please send me more information on:(1IC Troubleshooters ( ) 8015A Digital Pulse Generator: ) 5000A Logic Analyzer ( ) 9560B/D Automatic Circuit Tester

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Page 6: Rili - Science...If you've everhadto troubleshoot a digital circuit withtraditional analog instru-ments, the experienceprobably convinced you there shouldbea better way. Takevoltage

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Page 7: Rili - Science...If you've everhadto troubleshoot a digital circuit withtraditional analog instru-ments, the experienceprobably convinced you there shouldbea better way. Takevoltage

isthenew lookin unbreakableNalgene® BuretsThese burets do everything glass does

except break. Now youcan have an individually cali-brated transparent buretthat will not break in normaluse. Only a slight meniscusmakes readings easier, moreaccurate. The crystal clearacrylic body, tip, and leak-proof stopcock are unaf-fected by all the usual ti-trants. The Teflon TFE plugnever needs lubrication, is apleasure to turn. Stopcockassembly easily removed forstraight-through cleaning.Clearly the precision buretsfor industrial labs, schools,and in the field. Sizes: 10,25, 50, 100 ml. (Cat. No.3650). Order from your LabSupply Dealer. For furtherinformation write Dept.4211A Nalgene Labware Divi-sion, Rochester, N.Y. 14602.

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the per a _epI I

Wade] were interesting to read andtook me back to my boyhood, when Ienjoyed collecting insects.

In New Hampshire in the summerof 1919 the sugar maples were com-pletely defoliated by the rosy maplemoth, Dryocamnpa rubicunzda. In 1920the maples were normal. In the mapleforests, my joy, as a collector of beetles,was great because the woods wereswarming with Calosoma frigidiuml eat-ing the larvae of the moth. At homein New Jersey, I visited a friend onhis farm where potatoes were beingdug. The insecticides 50 years ago werenot as effective as they are now; thatpotato field was swarming with Calo-soma calidtiwn, which had been feedingon larvae of the potato beetle, Lep-tinotarsa decemlineata.

I am not an organic gardener, but inmy vegetable patch I cultivate the lazyway with a minimum of plowing andsome mulch of leaves and shreddedsticks. I have not sprayed or dustedfor several years. The corn ear wormsand bean beetles are there, but theirdamage is small.

I suppose my farmer friends areright in saying that it is not eco-nomically practical to rely on naturalpredators for control. I am a chemistand so should probably not speculate,but I wonder what would result if aCalosomia, full of eggs, could be keptalive in cold storage to' be releasedwhen pest larvae were hatching. Clau-sen (1) names many insects, some withunrestricted feeding habits, which mightbe treated this way. Could not some ofthese be used to control the gypsymoth?

EDWARD C. HAINES501 East Main Street,Moorestown, New Jersey 08057

References

1. C. P. Clausen, Entomophagous Insects (Mc-Graw-Hill, New York, 1940).

University Cooperation with Industry

The spirited discussion by G. D.Cody, W. D. Compton, and R. Roy(Letters, 31 Aug., p. 800) of Roy'sarticle (1 Dec. 1972, p. 955) on uni-versity-industry interaction patternsprompts me to mention our experienceat Carnegie-Mellon University, wherethe Processing Research Institute (PRI)was organized with a grant from theRANN (Research Applied to NationalNeeds) program of the National Sci-ence Foundation (NSF). PRI benefits

434

from what Cody calls a "troika," inwhich government funds are used as a"icatalyst" to bring industry and the uni-versity together in a meaningful way.During the 1972-73 academic year,PRI cooperated with 14 companies inprojects having an annual value of$500,000. Approximately 60 percent ofthe funds were provided by industry.A key feature of PRI is a 2-year

Master of Engineering degree programwhich provides for a diversified, broadcurriculum. PRI attracts problem-oriented graduate students who con-sider their industry-sponsored projectto be a vital part of their education.Aspects of our experience that we thinkare critical for successful industry-uni-versity interaction are (i) an identifi-able organization on campus that in-teracts with industry-at Carnegie-Mellon, the PRI; (ii) a broad base ofdisciplinary support-in our case, fromthe departments of chemical engineer-ing, mechanical engineering, and metal-lurgy and materials science; (iii) suffi-cient faculty of acknowledged com-petence who are willing to enthusiasti-cally support this type of activity; and(iv) encouragement and support fromthe university administration.

As Cody has indicated some doubtconcerning the feasibility of an effectiveindustry-university partnership, it isimportant to mention some of the bene-fits to the university we have observedin a brief span of time: (i) the devel-opment of a problem-oriented graduateprogram that parallels the traditionaldiscipline-oriented programs; (ii) abroadened outlook on the part of thefaculty; (iii) an increased interactionbetween the three cooperating depart-ments; and (iv) increased support ofthe graduate program through industry-sponsored projects. From the point ofview of industry, the opportunity toprovide a positive input to graduateeducation, especially in the developmentof new approaches to problem-solving,is gratifying. Representatives of in-dustry who visit our campus seem tobenefit from the broad view that our

faculty takes of their disciplines, whichhas led to some unusual solutions toindustrial problems.

Finally, one of the objectives of theNSF grant is to experiment with dif-ferent forms of industry-university in-teraction. We invite comments andsuggestions.

GEORGE E. DIETERProcessing Research Institute,Carnegie-Mellon University,Pittsbuirgh, Pennsylvania 15213

SCIENCE, VOL. 182

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Page 8: Rili - Science...If you've everhadto troubleshoot a digital circuit withtraditional analog instru-ments, the experienceprobably convinced you there shouldbea better way. Takevoltage

As late as the year 1973, such news items still turn up.The photographic emulsion has not yet had all itspotential wrung out of it. Nor have all useful changesbeen rung on it yet.

There is a problem, though: building new propertiesinto modern photomaterials is an undertaking of somedimensions, including the commercial dimensions.Those count because it takes quite a bit of stuff just towet the equipment. We are simply not clever enoughto make do with a beaker and a pancake griddle andget film sufficiently predictable in performance tocarry the trademark "Kodak." A scientist who expectsto use as much as 1 m2 of a very special film mayresent paying a price for it that covers the 500 m2 ofunsalable goods generated in startup.

Meet two individ-uals at the interfacebetween such inner

realities and outerneeds. Scott, with the

dark beard, has thetask of finding corn-

mon threads in pho-tographic needs

among the biomedical research community (and a

few other learned communities). The gray-beard,Hahn, serves astronomers and works inward fromtheir world. Nimbly up and down the scale of tech-nical photographic sophistication, they talk and writethe whole day through. To wit:

Kodak, what's your fastest material?Answer: If you are talking in microseconds, KODAK

2485 High Speed Recording Film (EsTAR-AH Base),stocked only in 150-foot lengths, 35mm or 70mm. Ifyou are talking hours or days, KODAK "Spectroscopic"Plates, Type Ia. Use Ia to demonstrate the presence oflight but not to find a faint image amidst other radia-tion. For that, get IIIa-J and bake for five hours at65°C under dry N2 before exposure.

Kodak, is it true that certain of your films are"classified"?

Answer: No.Let's chat color film. What's your fastest in

35mm?Answer: KODAK High Speed EKTACHROME Film

(Daylight). ASA 160 in normal processing. Can bepush-processed to higher speeds by processing labs (toASA 400 in the case of Kodak Processing Labora-tories; other laboratories may go higher). You can alsouse a KODAK EKTACHROME Film Processing Kit, Pro-cess E-4, and regulate effective film speed yourself bytime in first developer. Get too far off the recom-mended time and brace yourself for disappointingimage and color quality, if that matters in your applica-tion. If you leave the film in overnight, don't blame us

for your sad results.

Which color film for high contrast in lectureslides of charts?Answer: KODAK Photomicrography Color Film.

More of it is used that way than in photomicrography,we suspect.Why do my false-color studies on the KODAK

EKTACHROME Infrared Film come out blue?Answer: Maybe you are not using a KODAK

WRATTEN Filter, No. 12 (or equivalent), as recom-

mended.Why have you quit making WRATTEN Filters?Answer: We haven't. We've just quit mounting

them in glass.How can I get photographic sensitivity below

250 nm?Answer: To get down to 200 nm, bathe plates be-

fore exposure in Ultraviolet Sensitizing SolutionA3 177 (sold by lab supply houses that handleEASTMAN Organic Chemicals). KODAK SWR Platesand Film have recorded down to 7.5 nm, but deliverytime runs 60 to 110 days, and sensitivity to abrasionruns high. Kodak-Pathe in France makes some filmsthat can give you an order of magnitude more in sen-sitivity to the deep UV than SWR plates. Check withEd Hahn.How can I get above the 900-nm limit of KODAK

High Speed Infrared Film?Answer: Bathe KODAK "Spectroscopic" Plate I-Z

for 3 minutes at 5°C in 0.5% aqueous ammonia, thenfor 2 to 3 minutes in methanol or ethanol. Dry as

quickly as possible in stream of cool, dust-free air.Expose and process without delay. Radiation out to1.28 pm has been recorded that way.

Is that what's used in those infrared cameras tophotograph differences in water temperature?

Answer: No. Those are scanners with photoconduc-tive cells cooled by liquid N2. A resulting CRT displayis then recorded photographically on film recom-

mended for the equipment. For subjects below 250°Cyou don't record temperature differences directly on

silver halide.Do I order these various films from Kodak?Answer: No, from dealers in professional and in-

dustrial photographic goods. The Yellow Pages mightguide you to one such. Many are accustomed to serv-

ing scientific customers. Just ask.

Keep this page handy for a while but not fortoo long. The answers are not to be con-strued as eternal truths. Mail address forthis sort of thing: Kodak, Scientific Photog-raphy Markets, Rochester, N.Y. 14650.

ITEM: Airglow ITEM: Water penetrationNature 242:321 reports evidence that direct photography An experimental color film of two layers with peak sensi-of airglow at ff1.2 through KODAK WRATTEN Filter 88A on tivities at about 480 and 550 nm, in which magenta andKODAK High Speed Infrared Film might be an easier way green dyes respectively are formed, is reported to showto prepare world-wide synoptic maps of "'winds" at the OH superior results from aloft in delineating underwater detaillayer of the atmosphere than are obtained by vapor re- and characteristics of the water itself. The film is not yetleases from rockets or analyzing persistent meteor trails. ready for sale.