ELEC2607W96 - CARLETON UNIVERSITY 5( FINAL Name EXAMINATION...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 2
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 4
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 6
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 8
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: CARLETON UNIVERSITY 5( FINAL Name EXAMINATION April 1996 Number DURATION: 3 HOURS N0 of Students: 94 Department Name & Course Number: Electronice 97.267 Course Instructor(s) T.G. Ray AUTHOIIZKD “CUB-Q'CDI Any books or notes; any non—communicating calculator. Students MUST count the number of pages in this examination question paper before beginning to write, and report any discrepancy immediately to a proctor. This question paper has eight pages. This examination question paper may not be taken from the examination room, —-——m—_—.._____—___—_—___ INSTRUCTIONS: Open book. No talking. Attempt all questions. Place all responses on the front sides of the examination sheets unless otherwise instructed. If you absolutely must respond to a question using the answer-book, please put a clear note on the question referring the marker (me!) to your answer. If you do not understand a question or think there is an error, make a reasonable assumption and state it clearly. Consider only one input to a circuit to change at one time (unless specifically instructed otherwise). The exam marks total 95. 1. Short Questions (25 marks total) lai) Redraw the following circuit using only NAND gates and as few inverters as possible. (3 marks) A 3 F’ A 5 Answer: laii) What two words best describe the two ways in which the NAND implementation is better than the original? (2 marks) Answer 1 : Answer 2: 11)) Circle all of the prime implicants on the following S—variable Kamaugh-map. Unfilled locations are actually all 0. (4 marks) If you mess up the first map, use this copy: Do 01 1 1 1 o 00 01 11 10 1c) ' delay in the proper place is a practical and sure method of fixing a design i) a static hazard ii) a dynamic hazard iii) an essential hazard Answer: yes/no Answer: yes/no Answer: yes/no Ii 3 K 1d) Why were the flip—flops used in this course exclusively D-type, and the use of other types forever discouraged? (In 25 words or less.) (3 marks) Answer: 1e) What one word best describes the reason why the clock inputs to flip—flops in this course were always tied together and to one master clock? (One word.) (2 marks) Answer: It) Give a new equation for F: ACE+BCD+EB which has no static hazard problems. (4 marks) Answer: F = 1g) Prove or disprove, without the use of Boolean algebra or any theorems, that (A+1§)(K+C)(B+C) = (A+B)(K+C) (4 marks) Answer: 2. Machine (8 marks total) Clk I State Rll ||||| | Ill | I l I Output 3.) Fill in the states and the output waveform for the above timing diagram using the state graph given. (6 marks) b) Find an impossibility in the above state graph, circle it, and say what it is. (In 10 words or less.) (2 marks) Answer: 1L Q .i . l. 1 I 1 i ! :: i i E; I i i: E i ‘ l . l : 1' i 5' ‘ = i : I: t : 5. I !I i ! i; i i: r I i: l E t i x I i; \ E ; | E! l u :' ‘ - .. l i 'i ‘> 3. Synchronous Circuit Design (15 marks total) A Moore machine is to have two inputs, X and Y, and one output, F. X and Y each receive independent sequences of ls and Os synchronized to a single clock. Design an efficient circuit, using one flip—flop and a minimum of logic, to make F = 1 whenever the number of Is received so far in the X sequence PLUS the number of Os received so far in the Y sequence, is evenly divisable by 2, i.e. divisable by 0, 2, 4 , 6... . Put your solution in the answer—book. Show all of your work. 4. Asynchronous Circuit Design (20 marks total) a) Three individuals, William, Xavier and Yolanda, each have a push-button and a light hooked up to an asynchronous circuit you are to design. The circuit is to indicate who pushes their button first, by pennanently lighting their light and forever preventing the other lights from coming on. The three individual’s push—button inputs are conveniently designated W, X and Y, and the corresponding outputs are Wo, X0 and Y0 (o = output). Considering in more detail the exact operation of the W0 output as an example: We should be set to 1 if and only if: - the W button is pushed, i.e. W=l, - while neither the X nor Y buttons are pushed, i.e. XY=00, — and neither the X nor Y buttons have ever before been pushed, i.e. XoYo=OO. And once We is set to 1 it should stay set forever. The other buttons should make the corresponding circuit outputs behave similarly. To start the entire circuit in the reset condition there should be an overall RESET input, which you are assured will be pushed only once to initialize the circuit when it is first turned on. Your design does not have to consider races or hazards. You may design just 1/3 of the entire circuit, as long as it is representative of the other 2/3. (17 marks) Put your solution in your answer-book. Show all your work. b) For your design, what would be the values of the three outputs if W, X and Y were all depressed at EXACTLY the same time? (Your design doesn’t have to deal with this situation.) (3 marks) Put your answer for WoXoYo in your answer-book as well. jfl 5. Critical Races and Essential Hazards (12 marks total) A specific asynchronous machine has the transition table shown in the seven identical copies below. Not everything is represented in the copies, and they may or may not all be needed, while the three at the bottom are spares for rough work or in case you mess up the earlier ones. a) Circle all the stable states on the first table. Indicate two critical races (if that many exist), each by arrows showing the paths taken through the next-state part of the table, from the initial stable state to the final stable states. Show only one critical race per table. Critical Race: AB A+B+ XY=00 01 1 l 10 00 1 l l 1 10 00 01 I 1 01 00 01 1 1 1 1 10 01 11 10 10 10 1 l 01 Critical Race: AB A+B+ XY=00 01 l l 10 00 ll 1 1 10 00 01 l 1 0 1 00 01 1 1 1 l 10 01 l 1 10 10 10 l 1 01 b) Indicate two essential hazards (if that many exist), each by arrows showing the paths taken through the next—state part of the table, from the initial stable state to the final stable states. Show only one essential hazard per table. Essential Hazard: AB A+B+ XY=OO 01 11 10 00 11 11 10 00 01 11 01 00 01 11 11 10 01 11 10 IO 10 11 01 5. Races and Hazards (cont.) Essential Hazard: AB A+B+ XY=00 01 11 10 00 11 11 10 00 01 11 01 00 01 11 11 10 01 11 10 10 10 11 01 Spare: (For rough work, or write in which part of the question you are using it for or it won’t be marked.) AB A+B+ XY=00 01 11 10 00 11 11 10 00 01 11 01 00 01 11 11 10 01 11 10 10 10 11 01 Spare: (For rough work, or write in which part of the question you are using it for or it won’t be marked.) AB A+B+ XY=00 01 11 10 00 ll 11 10 00 01 11 01 00 01 11 11 10 01 11 10 10 10 11 01 Spare: (For rough work, or write in which part of the question you are using it for or it won’t be marked.) AB A+B+ XY=OO 01 11 10 00 11 11 10 00 01 11 01 00 01 11 11 10 01 11 10 10 10 11 01 6. Critical-Race—Free Asynchronous Circuit State Assignment (15 marks total) For the following state table, revise the table and select a critical-race-free state assignment- Do not change the machine any more than necessary. Keep A as state 001, and do not increase the number of rows in the table. Enter all of your answers on this page. Present Next State Output State XY=OO 01 1 1 10 XY=OO 01 1 1 10 A=001 C D A A —— -— 0 0 B B B A B 1 1 -- 1 C C —— E C 0 -- -— 1 D D D —- B 1 0 —— —— E -- D E A —- —— 1 —— —— = “don’t care” Answer: Your state assignment: 0 1 00 01 l 1 10 State table showing just your revisions: (Use letters to represent states, as above.) Present Next State Output State XY=OO 01 1 1 10 XY=00 01 1 l 10 A=OO 1 B C D E / 7/? K ...
View Full Document

Page1 / 8

ELEC2607W96 - CARLETON UNIVERSITY 5( FINAL Name EXAMINATION...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online