Mon, 31th Aug 2015, 22:23 Two birds with one stone, as they say!

My EE 306 students:

This email to you all is to solve two problems.  First, I want to make sure
we are all connected via email.  I will send you a lot of email throughout
the semester, and I want to be sure you get it all.  Recall, I said that
you need to check the EE306 webpage every other day.  Sometimes I don't want
you to wait that long and so I send email directly to you.

In class on Wednesday I am going to check to see if anyone did not get this email.
If you are reading this, you are not one of them.

The second thing this email is going to do is respond to a question one of my
TAs sent me in email an hour ago.  The TA wrote:


> Dr Patt,
>
> I forgot to mention this earlier, but a couple of students asked me if data
> types are a part of HLL, or ISA. I think you didn't mention it when you
> were talking about it. Maybe you could bring it up on Wednesday?
>
> Thanks,
> <<name withheld to protect the identity of the conscientious TA>>


Like too many terms in computer technology, the term "data type" is used in
different contexts, and so the correct answer to your question is: both!

In EE 306, we are concerned mostly with the ISA, and only incidentally with
high level languages.  So, in 306, when I speak of data type, I am referring
to the ISA.

To understand how it pertains to the ISA means first of all, one needs to
understand what an ISA is.  You will become very familiar with the notion of ISA
in a few weeks so I do not want to belabor the definition here.  My automobile
analogy for some reason did not work this semester, so I am reluctant to spend
more time on it now.  It is not necessary for you to understand it now, and I am
concerned that it will confuse you further unnecessarily now.  You will see it in a
very few weeks, and then you will understand it (trust me!).

However, to satisfy those in the class who have had no trouble getting the concept
of ISA, I will make one additional comment.  For those of you who are still confused
by the notion of ISA, please stop reading now, but save my comment for three weeks
from now, and look at it then.  It really does not matter if you understand it now,
or have to wait until we get to chapter 5 in the book.

My additioal comment: The ISA consists of, among other things, all the instructions
that the computer can execute, and everything that is needed to carry out the work
of each instruction.  For example, if one of the instructions the computer can
execute is to add two numbers, those two numbers must be represented with bits
such that the computer can perform the addition with that representation of those
bits.  We say that representation is a data type because there are instructions in
the computer that will do its job on numbers when they are  represented in that way.

If this does not help, then please wait until we get to chapter 5.  I promise it
will make sense then.



Yale Patt