in reply to Reading the manual and knowing if you are getting good

Is your EE lecturer's quote "You know when you are getting good, when you just see things" about circuits?

There comes a point in understanding circuits where you can look at a schematic and read the intent of the design, and understand its operation. Although the diagram may show an ocean of resistors, capacitors, inductors, transistors, transformers, connectors, etc, you get to the point where you just see the flow and understand the circuit (if it is well-drawn).

Many flaws in circuit design can be spotted by inspection. Your eyes are drawn to problem areas, where things just don't look right. This is not a brute-force calculation. It is similar to chess, where a master sees only a few moves where there are opportunities. This is in contrast to a computer, which plays chess by evaluating myriads of moves.

When you get really advanced, you can even see humor in some schematics, both in the way the diagrams are drawn, the choice of components, and the topology. When someone points and laughs at your schematic, it is not unlike the experience of someone pointing and laughing at your code.

In many ways reading code is harder than writing it. You are good when you can read someone else's code, appreciate what is good about it, and see where it is likely to have problems. This can be done quite quickly and intuitively.

I am much better at reading schematics than reading perl code! There are many great books that help you learn to read code, though. For help reading schematics, the titles are far fewer. 'The Art of Electronics' by Horowitz and Hill is the title that comes to mind for circuits.

Like a well-coded test suite, a very thorough simulation of an electronic design can result in detailed analysis of design flaws. I have found that these thorough simulations must be created by someone who understands the circuit. In other words, black box simulation does not work for the types of analog designs that I look at. This leads me to suspect that software test development is also not best when it designed on a black-box.

The analogies between hardware and software run deep.

It should work perfectly the first time! - toma
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Re^2: Reading the manual and knowing if you are getting good
by ghenry (Vicar) on Jun 01, 2005 at 07:34 UTC

    Yes it was.

    I also have that book. He was the best lecturer I ever had.

    He worked for Hughes at 20 and helped design the propulsion systems for the Firebird/Firefox aircraft. He also helped develop the first ever Virtual Reality System for the Military and now works on Propulsion systems for space crafts, I think.

    Walking the road to enlightenment... I found a penguin and a camel on the way.....
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Re^2: Reading the manual and knowing if you are getting good
by BrowserUk (Pope) on Jun 01, 2005 at 07:51 UTC
    This leads me to suspect that software test development is also not best when it designed on a black-box.

    Amen to that.

    Years ago I was responsible for defining the test plan for an OS/2 replacement for a previos DOS app. I was given the IT department generated (black-box mandated) test plan for the original as a starting point. It consisted of a stack of green&white lined fanfold about 7 inches thick. The first 1 1/2" of that were the tests for checking the handling of the applications configuration file.

    Of the 20-something lines in the file, 14 were fully qualified path names to various other files. For each of these there was a comprehensive set of tests that consisted of manually editing the line of the config file to introduce particular errors (non-existant drive letter; non-existant directory; space in a directory name; space in a filename; non-existant file; etc. etc.) and then running the program and ensuring that it detected the errors. This batch of tests (the first 1 1/2") took 2 people a week to run.

    Looking inside the code, it was obvious that

  • If the errors were detected in one of the 14 lines, they would be discovered in all of them.
  • The program simply passes the path as read from the config file to the CRT open() and reported back whatever errors it found.

    Given that the waterfall development method required that these tests be re-run every time the program was modified--even if the change was a totally trivial spelling correction; or something major but in a completely unrelated part of the program--the cost of that "black box innocence" to the reality of the inner workings was huge over the 7 years and hundreds of versions that had been tested.


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    Lingua non convalesco, consenesco et abolesco. -- Rule 1 has a caveat! -- Who broke the cabal?
    "Science is about questioning the status quo. Questioning authority".
    The "good enough" maybe good enough for the now, and perfection maybe unobtainable, but that should not preclude us from striving for perfection, when time, circumstance or desire allow.