A student writes:

	Dear Dr. Patt,

	I'd like to verify a few things on Appendix C with you.  Please let me
	clarify followings;

	1.	On page 2 sentence number two, inst[15:12] and inst[11:11] were
	used.  Is this same as IR[15:12] and IR[11:11] as most of diagram 
	refers?

Looks like it.  inst[a:b] refers to a field in an instruction, and the IR is where 
instructions sit after they have been fetched.

	2.	On page 3 section C.2 first sentence.  7 signals and 
	what signal (I can subtract, but I was confused) would make 
	35 signals?  I think something was missing from the sentence.

I do not understand what you are asking.  The sentence reads: The behavior 
of the LC-3b is controlled by 35 control signals + an additional 7 signals.

If you look at the block diagram, you will note that 26 of the 35 control the data path, 
while the other 9 of the 35, combined with those additional 7 control the microsequencer.  
That is 9 + 7 (i.e., 16 control the microsequencer.

	3.	On Figure C.1, is the "control signals" same as 
	Microinstruction in the section C.4 or Figure C.4?

Yes.  In figure C.1, we are giving an overview for ALL microarchitectures. By the time 
you get to C.4, you are talking about one instance, where the control signals are obtained 
from a control store, and referred to as a microinstruction.

	4.	On Figure C.1, is the "control" same as combined block of
	Microsequencer and Control Store in Figure C.4?

Same as #3.  C.1 covers all implementations.  By the time you get to C.4, you are dealing 
with a specific implementation.

	5.	On section C.5.1, what is "A MUX" and "A second MUX"?  
	Could you show me on Figure C.2?

Great question!  Both MUXes are inside the block labeled LOGIC that uses MDR as input, 
provides its output to the bus, and has two control signals, DATA_SIZE and MAR[0].  Let's 
add this to the problem set:

Problem 11.  Show the logic required to implement the block labeled LOGIC that is specified 
by section C.5.1.

	Thank you for your time,

	<<name withheld>>

Thank you for providing a great problem for the problem set.

Yale Patt

ps. Are you working alone, or in a study group.  Students generally do better when they work 
in a group.  Good luck with the course.