Sun, 5 Oct 2014, 1:25am

My students,

I have gotten more than a few emails regarding the exam, so I thought I would
clear up some questions.  The email may appear long, but I think it is a quick
read, and I recommend you take the time to do so.

The exam will be conducted in two rooms, our classroom GSB 2.126 (for those
whose last names start with A to K) and PHR 2.110 (for those whose names start
with L to Z).  You will need your student ID card when you hand in your exam,
so please do not forget to bring it.

You do not have to buy any exam books.  You will be handed the exam, and you
will write all your answers on the exam itself, which you will turn in by the
end of the exam period.

The exam is closed book.  ...which often results in memorization, and
I absolutely do not want you to memorize.  My simple solution
is to invite you to bring into the exam three sheets of paper on which you
can write anything you would otherwise feel necessary to memorize.  The
sheets of paper can be as large as you want and the writing can be as tiny
as you want BUT a MAXIMUM of three sheets of paper.  One student asked me
why that is any different from simply bringing in his notebook.  It is, and
I will be happy to explain the difference and my rationale at some later date.

In fact, the only things allowed in the exam are the three sheets of paper,
the exam that you will receive and any pens/pencils you need for writing.
No cell phones, backpacks, calculators, etc.  If you do bring them to the
exam, please put your backpack at the front of the room, and put cell phones,
etc. either in your pocket (never to be taken out during the exam) or in your
backpack.  I do not like insisting on these *rules* but I insist on having
a level playing field for all of you, and providing opportunities for some
to destroy that level playing field is something I try very hard to avoid.
Violating these rules is considered cheating.

Now, some comments on some of the material of the course.

The single thread parallelism slides that I promised you.  They are now on
the course website.

The I/O material.  I have posted a handout I wrote for 460N the last time
I taught the course.  You will notice a few new things.  For example, I pointed
out the difference between a pending bus and a split-transaction bus.  A pending
bus is one in which the bus master ties up the bus throughout the transaction,
regardless how long it takes.  A split-transaction bus is one in which the
bus master recognizes that it will take time before the slave can supply all
the data, so once the master knows that the slave can start working on getting
that data, the master releases the bus so others can use it.  When the slave
is ready to supply the data and finish the transaction, it (the slave) becomes
the master and initiates the completion of the bus transaction.

Another item on the I/O handout.  You will notice that a controller that
does not want the bus forwards the BG signal until it gets SACK.  Unfortunately
that does not always work.  In class I showed the correct input signal to the
controller that caused it to stop forwarding the BG signal.  It was NOT(BGin)
and that input always works!  Why does SACK not always work?

Also, with I/O, I sent you all an email on September 24 containing
figures that I drew from my ascii terminal.  A few of you had trouble
reconstructing the figures from what appeared on your screen.  We have posted
that email in the Email archive after cutting and pasting the figures so they
now show up very readable.

Finally, the Intro lecture that was posted on August 28.  Some of you had
trouble getting it from the website.  That, too, has been fixed.

I think that should do it.  Good luck studying for the midterm.


Yale Patt