Sun, 25 September 2016, 22:52

I got email from a student two hours ago.  A little late, but I will
respond anyway.  Most students, I assume, interpreted the sentence as
we intended.


> Hello Dr. Patt,
>
> Can you clarify what "instructions your simulator sees comply with the ISA
> specification." means? Does this mean that we can assume the instructions
> are all valid and do not try to access out of bounds memory or does it just
> mean that the instructions are assembled properly so that it follows all of
> the lc3-b specifics?
>
> Thanks,
> <<name withheld to protect the student who does not realize how nice I am>>


Indeed, I could have asked you to process each instruction taking into
account all the things that could be wrong with a particular instruction
you are writing code to process.  Like for example, the contents of a base
register is odd, an offset is even, and you are doing a LDW or STW using
that base register.

We will deal with all that in later labs.  In the interest of easing you into
implementing computers, the statement you are referring to means that you can
assume that every instruction is a legitimate instruction according to the ISA
and that every instruction can be processed without problems (like unaligned
access, for example).

Good luck with this lab and the rest of the course.


Yale Patt