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ECE 190 Midterm Exam 1
Spring 2011
Wednesday, February 1 6 , 2011
Name: NetID:
- Be sure your exam booklet has 5 pages.
- Do not tear the exam booklet apart.
- Write your name at the top of each page.
- This is a closed book exam.
- You may not use a calculator.
- You are allowed one handwritten 8.5 x 11" sheet of notes.
- Absolutely no interaction between students is allowed.
- Be sure to clearly indicate any assumptions that you make.
- Don’t panic, and good luck!
Problem 1 10 points _______________________________
Problem 2 5 points _______________________________
Problem 3 10 points _______________________________
Problem 4 5 points _______________________________
Total 30 points _______________________________
Problem 1 (10 points): Binary representation
Part A (2 points): What is the 8-bit result of adding the following pairs of 8-bit numbers
together?
a ) 01110111 + 00101001 = _________________________
Assuming 8-bit 2’s complement representation, is there overflow? (circle one) yes no
Assuming an unsigned representation, is there overflow? (circle one) yes no
b ) 11100111 + 01110010 = _________________________
Assuming 8-bit 2’s complement representation, is there overflow? (circle one) yes no
Assuming an unsigned representation, is there overflow? (circle one) yes no
Part B (2 points): Convert decimal number - 128 into signed magnitude, 2’s complement, and
1’s complement binary representations using the minimum number of bits.
Signed magnitude: _____________________
2’s complement: _____________________
1’s complement: _____________________
Part C (1 point): How is the number - 4.875 represented in the floating point data type format?
Answer: _________________________________________________
Part D ( 2 points): In homework #1 you calculated the accuracy of the floating point
representation of e. How accurate is the floating point notation when the largest possible number
is represented using this notation (with the exponent field being within the range of 1 to 254)?
Answer: 2
N
, where N =___________________________________
Part E ( 3 points): Using binary integer arithmetic, what 32-bit pattern can be added to this
floating point representation to effectively multiply it by 3? (Hint: 3 = 2 * 1.5)
Answer: _________________________________________________
Problem 3 ( 10 points): Memory
A multi-level cell (MLC) is a memory cell that has more than 2 states, allowing it to store more
bits of information in the same space. In this problem, you will be working with 4-state MLCs
that each store 2 bits of information. Given four 4 - state MLCs, build a 2x4-bit memory unit
using only AND, OR, NOT gates and MUXes:
If you need to merge two 1-bit wires into a single 2-bit wire, or to
split one 2 - bit wire into two 1-bit wires, you can use the following
notation where [0] and [1] indicate # of the 1-bit wire:
merge split
Problem 4 (5 points): C language
Part A (1 points): Assume variables x , y , and z are already declared. Write a C expression to
evaluate
!
!
!
Do not switch the order of operands.
Answer: ___________________________________________________
Part B (2 points): Fill in missing expressions to implement the following formula:
if ( _________________________________________ )
f = 1;
else if ( ____________________________________ )
f = - 1;
else
f = x;
Part C (1 points): Write the output produced by the following code segment:
int x = 10 ;
for (x = 0; x < 5; x++)
printf(“%d=“, x+2);
Answer: ____________________________________________
Part D (1 points): Using only declared variables, write missing arguments in scanf function
call that correspond to the provided format conversion specifications.
int day;
float temp;
char grade;
scanf(“%f %c”, _________________________________________ );
scanf(“%d”, _________________________________________ );
