Sun, 8 Dec 2013, 23:14

My students,

A student writes:

> Hello Dr. Patt,
> We discussed the state diagram of the I/O driven interrupt in my section 
> in depth, and we also talked about it some in lecture. My question is this: 
> are we expected to know the data path of interrupts for the final exam?
> I ask this so that I may focus on the topics that need my attention 
> the most.
> Thanks for your consideration,
> <<name withheld to protect the student who wants to waste no time learning
> stuff that will not be on the final exam>>

Perhaps I am being a little bit harsh with my choice of signature.  
But, ONLY a little bit.

Actually, his question serves a good purpose in that several students have
asked me how to study for the final exam.  What should I do, they ask?  Work
problems in old exams?  Work problems at the end of the chapters? problem
sets?  My answer is that all of these help, but the goal should not be to
memorize the flow of a problem's solution.  The goal should be to understand 
the concept that the problem addresses.  The student says his TA went over the
state machine for interrupts in depth.  Good!  The reason his TA did that was
to help students understand how interrupts work.  The state machine shows you
the state by state process. The data path shows you the structures that are
needed to process information.  Neither is an end in itself.  But both should
help you understand how interrupts work.  And THAT is what I want you to come
away with.

That was my long answer!  My short answer is: I don't care if you have
memorized the state machine for interrupt processing, or for anything else
for that matter.  I very much care that you understand how interrupts work.  
In fact, if I change the structure a little, and ask you to draw the state 
machine resulting from that change, you will be able to figure it out if 
you understand how interrupts work.

The above paragraph is not meant to make you uneasy.  It is just restating
what I have been saying all semester.  EE306 is all about providing you with
a foundation that is going to be very important next semester in EE319K and
beyond.  Understanding the concepts to the point where you can use them is
where it's at, and I hope my final exam tests that.

Good luck on the exam.  See you on Friday.

Yale Patt