# FinalS05b - ENGRD230 Problem 1 Analyze the circuit drawn...

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ENGRD230 Practice Test 2 Spring 2005 Problem 1 Analyze the circuit drawn below. J C K Q Q J C K Q Q CLK R R S 0 S 1 5V (a) Derive the next state equations for the JK F/Fs. (b) Draw a state diagram. (c) What does the circuit do? (d) Draw a timing diagram for CLK, S0, S1 for 8 clock ticks, assuming that the machine starts in state 00. Problem 2 Eliminate all equivalent states (equivalent in the sense de±ned in class) in the state table below where X denotes 1-bit input. Blank tables are printed for your convenience. You may use all or none of them. Present state Next state Output X = 0 X = 1 X = 0 X = 1 A B C 0 0 B D E 1 1 C H C 0 0 D H E 1 1 E F K 0 0 F H C 0 0 G F A 0 0 H D E 1 1 K H C 0 0 Present state Next state Output X = 0 X = 1 X = 0 X = 1

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Present state Next state Output X = 0 X = 1 X = 0 X = 1 Present state Next state Output X = 0 X = 1 X = 0 X = 1 Problem 3 (Read the problem statement carefully. There is only one correct interpretation of the problem). Consider a synchronous sequential machine of Mealy type with two 1-bit wide inputs A and B, and a single 1-bit wide output Z. Assume that the machine on POWER ON is put in to the state INITIAL. It stays in the state INITIAL as long as inputs on the line B are 0s. When a 1 appears on B, the machine leaves the state INITIAL. Whenever B becomes 0 again, the machine returns to state INITIAL. Let a 0 , a 1 , . . . a k , . . . be the string of bits that appear on A after B is asserted (becomes 1) and while B stays asserted. The bit a 0 appears Frst, the bit a 1 appears second, etc. The received sequence of bits a k a k - 1 ...a 0 represents a number A k , A k = k i =0 a i · 2 i . The machine is to recognize whether the sequence received on A immediately after B is asserted and while B is asserted, represents a nonzero number A k 6 = 0 divisible by 4. If it is, the machine outputs Z=1. In all other case the output Z is 0. Draw a state diagram for this machine. Name and explain meaning of all states.
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## This note was uploaded on 05/09/2009 for the course ENGRD 2300 taught by Professor Albonesi/long during the Fall '07 term at Cornell University (Engineering School).

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FinalS05b - ENGRD230 Problem 1 Analyze the circuit drawn...

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