Natural Science Forum / Physics / General Physics / July 2008

Jim, I never flame anyone. If you believe I do, it is you that is the
crank.

True, I often point posters of incorrect data on the newsgroup to
Physics 101 texbooks, and even have posted two suggestions on what
currently the best two of these books are.

This is how I help the newbies out, except for somtime sending them
used copies of quality physics textbooks. This provides them a basis
for learning more advanced material in physics.

I appreciate you saying that, but if you believe that I am a crank for
believing readers need to fully grasp physics at the 101 level before
that can advance to the 603 level, then you are the crank here.

Sorrry, when I was an undergraduate student, the competion was rather,
and on my first day in undergraduate school at Drexel, we were told to
look to the left of us, and then to our right. We were assured that if
we graduated, these two people would not. That was worse than fact,
since out of my feshman class in physics, nearly 40% actually
graduated with a BS degree in physics. From my friends at MIT and Cal
Tek, I understnand that the percentage is less than 30%.  Then too,
these are tougher schools than Drexel.

To hone our performance, unless you were a wiz-bang student, you lived
to learn with faculty ridicule for every mistakes you make on the
assigned problem sets, or on tests. This had two purpose, first to
cull the herd.  Second, to motivate students to the limits of their
abilities. I hated this at the time, particularly since I worked 8
hours after class to pay my tuition, and another 6 on physics problem
sets. I lost over 50 lbs while an undergraduate student.

Perhaps this I why I now make the same demand on the physics wannabes
as I was exposed to in college. I exposed those that worked for me in
industry to precisely that same treatment, no more of no less.  Most
responded, because they all wanted to be members of the A-Team, where
they earned annual pay increases 3X times that of other employees, and
nobody ever quit from my team in over 40 years.  I can only saythat I
must have screened them carfully doing their employment interviews.
Obviously the Human Relations department hated me, since I only hired
something like 15% of the job candidates that they submitted to me for
an interview. And trust me, most of the candidates that I interviewed
received higher score from me than from the people that worked for
me.  That was an education for me, and I learned that women
interviewer scoring female applicants were particularly harsh.  I
never did quite figure that one out.

If the candidate made it to me, I would ask on four questions, and
base my hiring decision on their answers to these four questions. Two
of these would deal with computer hardware, and the other two with
computer software design.  My questions were not very difficult,
because by the time a candidate reached me, they would have had to go
through 4 previous interviewers, each of who had the authority to show
the candidate the door, so by the time that they reached me, I knew
that they were frazzled.  So, my questiions were intentionally rather
basic for job candidates who held degrees both in EE and Computer
Science.  Citing them might help future job applicants.  Realize also
that the candidates answere is not graded except on his explanation.

1.  Explain the process of how addition is performed in a computer.
2.  Explain how you would go about diagnosing and correcting a
software problem in a computer where the program is contained in ROM.
3.  Explain what sort of a circuit you would employ to triple a clock
frequency produced by a quartz crystal time base.
4.  Explain why a chip embedded cache is preferable to an exernal
cache, and why an external caches is sometimes preferred.

Answers:

1. An XOR is first performed, followed by a ripple carry on a bit by
bit level.
2. A emulator with diagnostic capabilities is used to store the
program in a ROM emulator, which allows breakpoint and state
diagnosis.
3. You wold use a single ended, over driven amplifier because it is
rich in odd harmonics. A balance push-pull circuit cancels odd
harmonics.
4. Interconnects within a chip and much shorter and much faster that
connections via a motherboard.  The second part of this question is a
little sneaky, and focused on it the candidate knows the difference
between a primary cache and a secondary cache, and is willing to argue
the uses of each.

I hope that this helps someone on their next job interview, and
realize that if you make it to the guy that make the final decision,
the questions will not be identical, but hopefully this will give you
some idea of what that guy will be probing for. Realize that all of
the people that you speak to on a job interview are simply screens
except for that last inverviewer.  It is that kindly old guy or lady
that you meet lasr who decides if you will receive a job offer or
not.

See Jim, I am not really a mean bastard.  While what I just posted has
absolutely nothing to do with physics but may be beneficial to some.

Jim, I know that I something come across as being a little harsh on
slackers that turn to the newsgroups to solve their homework problems
for them, and I often am harsher still with the crackpots that post
their silly ramblings on sci.physics.

Harry C.