F08prelim2s - ENGRD 2300 Introduction to Digital Logic Design Prelim2 Solutions Fall 2008 ENGRD 2300 Fall 2008 Prelim 2 Solutions Problem 1(20

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ENGRD 2300: Introduction to Digital Logic Design Fall 2008 Prelim2 Solutions ENGRD 2300 – Fall 2008 Prelim 2 Solutions Problem 1 (20 points) Consider the following circuit: CLRN D PRN Q CLRN D PRN Q CLK D1 D0 Q1 Q0 X Z a) What are the excitation and output equations for this circuit? D0 = Q0 + X’ D1 = X’·Q0’ + X·Q1’ Z = X·Q0 b) What is the transition/output table? Solution 1 Solution 2 Solution 3 X X X Q1 Q0 0 1 Q0 Q1 0 1 Q1 Q0 0 1 0 0 11/0 10/0 0 0 11/0 01/0 0 0 11/0 10/0 0 1 01/0 11/1 0 1 11/0 00/0 0 1 01/0 11/1 1 0 11/0 00/0 1 0 10/0 11/1 1 1 01/0 01/1 1 1 01/0 01/1 1 1 10/0 10/1 1 0 11/0 00/0 Q1*Q0*/Z Q0*Q1*/Z Q1*Q0*/Z Other solutions are possible. 1

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ENGRD 2300: Introduction to Digital Logic Design Fall 2008 Prelim2 Solutions c) What is the state/output table for this circuit? Solution 1 Solution 2 Solution 3 X X X S 0 1 S 0 1 S 0 1 A D/0 C/0 A D/0 B/0 A C/0 D/0 B B/0 D/1 B D/0 A/0 B B/0 C/1 C D/0 A/0 C C/0 D/1 C B/0 B/1 D B/0 B/1 D C/0 C/1 D C/0 A/0 S*/Z S*/Z S*/Z d) Draw the state diagram for this circuit. A B C D 0/0 Solution 1 0/0 1/1 1/0 1/0 0/0 or 1/1 0/0 A B C D 0/0 1/0 Solution 2 0/0 1/1 1/0 0/0 or 1/1 0/0 1/0 B 0/0 1/1 0/0 0/0 0/0 or 1/1 Solution 3 1/0 C A D 2
ENGRD 2300: Introduction to Digital Logic Design Fall 2008 Prelim2 Solutions Problem 2. (20 points) A 74x163 synchronous 4-bit counter is often used to construct other types of counters by adding some additional logic. Using a single 74x163 counter and additional SSI logic gates, construct a counter that counts sequentially, except that it skips the number 8. I.e., this counter should count …, 0, 1, 2, 3, 4, 5, 6, 7, 9, 10, 11, 12, 13, 14, 15, 0, 1, … ENT CLR CLK ENP LD QA QB QC QD RCO 74x163 D C B A CLK GND VCC This problem requires that in state 0111 (but not 1111), LD is asserted and causes the constant ABCD = 1001 to be loaded as the next state. Note that it was acceptable to connect CLR, ENT, and ENP to inputs instead of Vcc. 3

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ENGRD 2300: Introduction to Digital Logic Design Fall 2008 Prelim2 Solutions Problem 3. (20 points) You are to design the transmission interface for an electric vehicle. The interface (i.e. gear shift) is to be controlled by a pushbutton in the manner of a semi-automatic transmission seen in some
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This note was uploaded on 12/25/2009 for the course ECE 2300 at Cornell University (Engineering School).

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F08prelim2s - ENGRD 2300 Introduction to Digital Logic Design Prelim2 Solutions Fall 2008 ENGRD 2300 Fall 2008 Prelim 2 Solutions Problem 1(20

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