Download ECE 2030 Spring 2001 Final Exam: Latches, Reverse Engineering, Assembly, State Machine and more Exams Computer Science in PDF only on Docsity!
4 problems, 4 pages Final Exam Solution 1 May 2001
Problem 1 (3 parts, 30 points) Art of the State
Part A (10 points) Implement a transparent latch using only six two-input NOR gates. Label the inputs In and En , and the output Out. No other gates should be used.
Out
En
In
Part B (10 points) Implement register with write enable using transparent latches, NAND gates, and inverters. Use an icon for the transparent latches. Label the inputs In , WE, Φ 1 , Φ 2 and the output Out.
In Out
En
Latch
In Out
En
Latch
WE
In
Out
Part C (10 points) Assume the following signals are applied to your register. Draw the output signal Out. Draw a vertical line where In is sampled. Assume Out starts at zero.
WE
In
Out
4 problems, 4 pages Final Exam Solution 1 May 2001
Problem 2 (3 parts, 40 points) Reverse Engineering
For each design below, determine the behavior and write as a Boolean expression.
OUTx = A ⋅( B ⋅ C )
OUTY = (^) ( B ⋅ C )+ D + E
OUTZ = A ⋅ B ⋅ C + D
A B
Out
A B Out
0 0
(^1 )
0 1
1 1
1
1
0
0
OUT = A ⊕ B = A ⋅ B + A ⋅ B
4 problems, 4 pages Final Exam Solution 1 May 2001
Problem 4 (2 parts, 30 points) State Machine
Part A (15 points) Using the following state table, complete the state diagram below. S variables are the current state. NS variables are the new state. S 2 S 1 S 0 NS 2 NS 1 NS 0 S 2 S 1 S 0 NS 2 NS 1 NS 0 0 0 0 0 0 1 1 0 0 1 1 0 0 0 1 0 1 1 1 0 1 1 0 0 0 1 0 0 0 0 1 1 0 0 1 0 0 1 1 1 1 1 1 1 1 1 0 1
Part B (15 points) Most of the energy used by current computers results from switching wires from 0 to 1 or from 1 to 0. Analyze this state machine sequencer and describe why it is superior to a traditional binary counting sequencer.
It’s better because: It has only one bit toggle per state transision.
