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SilkScarves Lover in silk cloth head masks......
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SilkScarves Lover in Seidentüchermasken......
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EEE Magazine
August 1970
Volume 18, Number 8
p36
Nick DeWolf Of Teradyne Speaks Out: Speed Kills
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Speed kills
I'm talking about the kind of speed that otherwise sane engineers build into semiconductors at the expense of reliability, economy, safety and everything else that should be holy. They do it because it's fashionable to be fast, and the rest of the world eggs them on by over-specifying speed, by demanding nanoseconds where milliseconds would do.
It's not hard to understand the pressures for speed. After all, it's easy enough to build an adder that adds, so once you've done that, you start looking for some other measure of how much you've pushed yourself. An obvious test is how fast you can add. Another is how small you can make the adder. Another is how reliable or inexpensive you can make it, but somehow that doesn't sound as exciting to most people.
Now, I am prefectly aware that there is an honest, legitimate requirement for speed sometimes, and if you have to go fast, you have to go fast. My point is that most of us don't have to go as fast as fashion tells us to go. And when you lose sight of that fact you pay through the nose, because speed - in anything from automobiles to pep pills to transistors - is always a bad bargain.
Here we really have a question of engineering sanity in setting design priorities. If speed is at the top of the list, everything else suffers. If, instead, an engineer backs off on speed in his design criteria and looks at total economic justification, reliability, etc., letting speed fall where it may, he will design a better system.
The urge to make things small, incidentally, is a blood brother of the urge to make things fast. Miniaturization can kill, too. Interestingly enough, these two yahoo concepts - speed and size - are in mortal conflict. Fast things are usually bigger than slow things, because there is more power to be dissipated, and more crosstalk and shielding to worry about.
Let's look at cases. Suppose an engineer designing a small computer rules out "slow" TTL logic in favor of ECI, thinking that in so doing he has not only shaved his delay times but also solved his glitch problems. But he soon finds that instead of eliminating glitches he has just moved the problem up to X-band, and now he has magnetic-coupling problems he never dreamed of before. If he's clever, he winds up no worse off than when he started, except that he may find his 1/4-inch-square device burning up 600 milliwatts, or about enough to melt the markings.
But that's only part of the story. The speed freak also throws away noise rejection, which is really the name of the game in industrial design. A high-speed device is always going to be more sensitive to high-speed digital noise than a slow-speed device. And what happens when a stray 5-nanosecond glitch puts a wrong bit into memory? That wrong bit sends the computer to the wrong address, which then gives the whole computer a nervous breakdown. A computer can be operationally destroyed by the funniest little noise that occurs once every six hours.
The extra power needed to go fast, also means extra heat, and this often means a cute little fan with its dirty little filter to carry away that extra heat. Everyone knows that the filters never get cleaned, and common sense tells you that the very presence of a fan means that the equipment needs free air, so where does that leave you? With a piece of equipment that was born to destroy itself.
Extra power also means extra money to supply the power. In the speed world of TTL, every dollar's worth of ICs need a dollar's worth of power supply. At that rate, an eventual billion-dollar IC market means a billion-dollar power-supply market. Zowie.
People who design and build industrial test equipment are as subject to speed pressures as anyone. But I believe that we should put these in their proper priority, which is after the pressures to test reliably, safely, and economically. And when we look for reliability, safety, and economy, we quickly learn that slow is good.
For openers, "slow" rejects noise.
A "slow" DTL circuit in an instrument will generate 1/100 the noise and be only 1/10 as sensitive to noise as conventional TTL. Of course, that means going four or five times slower than you could with TTL, but in many
36
part of an archival project, featuring the work of nick dewolf
© the Nick DeWolf Foundation
Requests for use are welcome via flickrmail or nickdewolfphotoarchive [at] gmail [dot] com
Arriving on Manchester's 23R
Airbus A380 - MSN 112 - A6-EEE
Airline Emirates
Status : Active
Registration : A6-EEE
Country : United Arab Emirates
Date : 1985 -
Codes EK UAE
Callsign : Emirates
Web site : www.emirates.com
Serial number 112
Type 380-861
First flight date 02/08/2012
Test registration F-WWAU
Engines 4 x GP7270
27/12/2012 Emirates A6-EEE
SilkScarves Lover in silk cloth head masks......
You can see many more pictures under “SilkScarves Lover” and “SilkScarves Lover_2”
SilkScarves Lover in Seidentüchermasken......
viel mehr weitere Bilder seht Ihr unter „SilkScarves Lover“ und „SilkScarves Lover_2“
My PowerBook meets its new baby brother - an Asus eee PC. Think the PowerBook has cause to be jealous...
The Asus is a £200 Wifi enabled laptop with flash memory (no hard drive) and a built-in web cam. It runs Linux - though you can put Windows XP on it (and OS X if you're kerrrrazy).
Now blogged here: www.suppertime.co.uk/blogmywiki/2007/11/asus-eee-pc/
EEE Magazine
August 1970
Volume 18, Number 8
p38
Nick DeWolf Of Teradyne Speaks Out: Speed Kills (cont'd)
____
when I say "slow" with reference to IC characteristics I don't mean glacial. When you do something in 50 nanoseconds, you're taking less time than it takes a typewriter key to move a quarter the wavelength of light. That's speed, no matter how you cut it. The problem is that what most people really want, if they only realized it, is results, not speed. They want to perform a given job in the shortest amount of time. People who test devices often use the term "productivity." Let me use an example to show that productivity and speed are not the same thing.
Suppose you're testing transistors, many thousands of them a shift, making 10 tests on each one and throwing them into bins on the basis of tests passed. Suppose each test takes 20 milliseconds. You can double productivity by cutting that test time down to 10 milliseconds, right? Wrong.
First, you find yourself bumping into some laws of physics. The transistor needs some time to achieve the desired test state and a measurement made too early might be invalid. Second, at 20 milliseconds a test you are probably already testing transistors faster than your mechanical handlers can operate. Third, you can really increase productivity by working out a test procedure that will eliminate superfluous and redundant test - in other words, one that will drop the transistor into the right bin with the smallest possible number of tests. This kind of planning can increase productivity by 30 or 40 percent.
Then figure out how to multiplex and time-share and use distribution curves and yield data to set bin priorities, and you might raise throughput by another 100 percent or so. That's what productivity is all about - not trying to puch ICs to their last nanoseconds.
Or, to put the matter in the latest context, consider the problems confronting those who want to test LSI devices. The fastest ICs anyone has dreamed up still fall pitifully short of doing the trick, because now you're involved in making, instead of a few dozen tests per device, n to the nth to the nth of them. Here speed doesn't kill; it simply fails. So again we attack the problem by reducing the number of tests required, through the generation of complex patterns.
Another factor that makes the speed race pretty academic is the amount of time required to program computer-controlled systems. And let's face it, computer control will soon overspread the whole range of electronic instrumentation. Once you enter the computer world, the key limitation isn't imposed by the speed of the magnetic memories, but by the level of complexity that you can tolerate. (Law: All things are as complex as the people involved can tolerate.)
A gang of monkeys sitting at typewriters for 40 years couldn't write the programs for what a computer-controlled test system can now accomplish in half a second. And future generations of test systems will even further outstrip programming ability.
That's the heart of the argument, really. We already have more speed than we know how to use. Our ability to absorb, reduce, and use information is limited not by some DTL gate plodding along at 50 nanoseconds but by the bandwidth of the people operating the system. There's a new paper shredder outside mu office. It shreds the paper none of us has time to read, and I have a dark suspicion that it is the paper shredder that ultimately will set the pace for all of us.
EEE
Who is Nick DeWolf
Even his friends feel that Nick DeWolf is a bit of a maverick. The president, director and cofounder of Teradyne just doesn't do things the way most of us would. When he left his job as chief electronics engineer of Transitron 10 years ago (he was the second employee), he didn't just shift into a job that was waiting for him. Instead, he took a year off to think and plan or, to use his own words, "to scheme."
He decided he wanted a partner so, instead of looking for a man with his own background and ideas, he sought one with entirely different experience. He found an old school buddy, Alex d'Arbeloff, who had been involved in South American real estate and who had worked for several companies that folded. This was Nick's way of preparing for lean years - but they never came. Teradyne has been an outstandingly successful manufacturer of equipment for automatic component testing.
Nick is a tall, gangly redhead who punctuates his remarks with frequent laughs, flailing gestures and a variety of sound effects. His family wanted him to be a banker but, as he expresses it, "I'm too skinny and I never played football well enough."
He calls his design philosophy creative pragmatism, which he spells out in terms of building better Mack trucks or doing well known things well. Despite his talk of sticking to "known" things, he's a compulsice inventor and has been since he took his BSEE at MIT in 1948. But he prefers to see himself as an architect. Thus, he didn't "invent" his company's SLOT machine (a Sequential LOgic Tester), he "architectured" it.
Nick, who walks to work (briskly), and his wife Maggie have six little DeWolfs and the biggest milk bill on Beacon Hill. When he's not running Teardyne, Nick is a sometimes (and expert) photographer, an avid skier and a civic leade who specializes in crossing the generation gap.
38
part of an archival project, featuring the work of nick dewolf
© the Nick DeWolf Foundation
Requests for use are welcome via flickrmail or nickdewolfphotoarchive [at] gmail [dot] com