This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: CPSC 121 Lecture 17 February 13, 2009 Menu February 13, 2009 Topics: Sequential Circuits (cont’d) Reading: Today: Epp 12.2 (pages 745–747), Designing a Finite Automaton (pages 752–754, skipping part b of the examples) Reminders: Assignment 2 due TODAY (by 17:00) Look for On-line Quiz 9 (Review) Marked Assignment 1 available in tutorials Midterm exam Tuesday, February 24 HENN 200/201 (6:30–8:30) Sequential Circuits (cont’d) Recall: MIT Course 6.004 Toll Booth Example The key observation for the proposed fix from this (automobile) toll booth example was, “At no time is there an open path through both gates.” Edge-Triggered Flip-Flop D G Q D G Q CLK D Q master slave NOTE: Only one latch “transparent” at any time • master is closed when slave is open • slave is closed when master is open There is no combinational path through the flip-flop! Edge-Triggered Flip-Flop: CLK = 0 (initially) Suppose CLK = 0 (initially) Master: Slave: G = 1 G = 0 Q follows (input) D Q follows (stored) Q...
View Full Document
- Spring '08
- Sequential Circuits, Edge-Triggered Flip-Flop, Suppose CLK changes