Department of Electrical and Computer Engineering
The University of Texas at Austin
EE 306, Fall 2004
Exam 1 Solutions
Yale N. Patt, Instructor
Siddharth Balwani, Linda Bigelow, Tommy Buell, Jeremy Carrillo, Aamir Hasan,
Danny Lynch, Rustam Miftakhutdinov, Veynu Narasiman, Vishal Parikh, Basit Sheikh,
TAs
1) Part a) An instruction set generally consists of three kinds of instructions:
_____
operates______
, an example of which is ___
ADD, AND, NOT
___
___
data movement
___, an example of which is ___
LD, LDR, LDI, LEA,
ST, STR, STI
___
______
control
______, an example of which is ___
TRAP, JMP, BR, RTI,
JSR
___
1) Part b)If we can implement any logic function using many copies of a single gate (or a
set of gates), then we say that single gate (or set of gates) is
logically complete (or universal)
1) Part c)A ___
logical or boolean
___ variable is a variable that can have one of exactly
two values. It gets its name from the fact that originally the two values were TRUE and
FALSE, and the awareness that the value of such a variable must be exactly one of these
two values.
1) Part d)If you know that R1 XOR R2 = 0, what can you infer about the contents of any
of the registers R0 to R7?
R1 and R2 must have the same values. Nothing about any of the
others.
1) Part e)What logic structure does a mux with the 0 input line tied to the select line
implement? Hint: Fill out the truth table.
If you fill in the truth table, you will see that it is an AND gate.
2) Part a)The following LC-3 instruction is fetched, loaded into the IR, decoded, and
executed.
0000 a b c 000000000
Note that bits [11:9] can each be 0 or 1. In ten words or fewer, what USEFUL