Exam Two for Computer Engineering Students in Spring 2012 (ECE 2030D), Exams of Computer Science

Download Exam Two for Computer Engineering Students in Spring 2012 (ECE 2030D) and more Exams Computer Science in PDF only on Docsity! ECE 2030D Computer Engineering Spring 2012 4 problems, 5 pages Exam Two 8 March 2012 Instructions: This is a closed book, closed note exam. Calculators are not permitted. If you have a question, raise your hand and I will come to you. Please work the exam in pencil and do not separate the pages of the exam. For maximum credit, show your work. Good Luck! Your Name (please print) ________________________________________________ 1 2 3 4 total 22 24 28 26 100 1 ECE 2030D Computer Engineering Spring 2012 4 problems, 5 pages Exam Two 8 March 2012 Problem 1 (4 parts, 22 points) Building Blocks Part A (6 points) Implement a 2 to 4 decoder with basic gates. I0 ¯¯¯¯¯ ¯¯¯¯¯ O0 I1 ¯¯¯¯¯ ¯¯¯¯¯ O1 EN ¯¯¯ ¯¯¯¯¯ O2 ¯¯¯¯¯ O3 Part B (8 points) Suppose the circuit below has the following input priority: I0 > I2 > I3 > I1. Complete the truth table by filling in the input values that would produce the given outputs and derive a simplified expression for O1. I3 I2 I1 I0 O1 O0 I3 I2 I1 I0 V O1 O0 0 X X 1 0 0 1 0 1 1 1 0 1 1 1 O1 = Part C (4 points) Which basic gate, having inputs X and Y, does the following circuit implement? Hint: Complete the truth table at the right. X Y Out 0 0 0 1 1 0 1 1 This implements a . Part D (4 points) If the mux in Part C is implemented with pass gates and inverters, does the implementation of the basic gate in Part C require fewer transistors than the gate's standard switch-level implementation? Circle one: Yes / No Support your answer by giving the transistor count for each: # transistors in MUX implementation: # transistors in switch-level implementation: 2